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Herwig Leirs - One of the best experts on this subject based on the ideXlab platform.

  • polymorphism in vkorc1 gene of natal multimammate mice Mastomys Natalensis in tanzania
    Journal of Heredity, 2015
    Co-Authors: Sophie Gryseels, Herwig Leirs, Rhodes H. Makundi, Joa Lle Goa Y De Bellocq
    Abstract:

    Resistance of rodents to anticoagulant rodenticides has emerged in several areas across the world. Single nucleotide mutations in the vkorc1 gene have been shown to elicit various levels of anticoagulant resistance, and these mutations are prevalent in several Rattus and Mus musculus populations. In sub-Saharan Africa, the Natal multimammate mouse, Mastomys Natalensis, is one of the most damaging pests to crops, and anticoagulant poisons such as bromadiolone are frequently used to control these rodents in agricultural fields. Here, we investigate if vkorc1 shows any polymorphism in natural populations of M. Natalensis. We sequenced the third exon of vkorc1 of 162 M. Natalensis captured from 14 different agricultural sites in Morogoro Region, Tanzania. In addition to 6 SNPs in the noncoding flanking region, we detected 3 nonsynonymous SNPs in this exon: 10 animals (6.2%) carried a Leu108Val variant, 2 animals (1.2%) an Ala140Thr variant, and 1 animal (0.6 %) an Arg100His variant, all 3 in heterozygous form. Ala140Thr is just one residue from a mutation known to be involved in anticoagulant resistance in Rattus and Mus. While in vitro or in vivo experiments are needed to link vkorc1 genetic polymorphisms to level of VKOR activity and anticoagulant susceptibility, our results suggest that M. Natalensis individuals may vary in their response to anticoagulant rodenticides. This is the first vkorc1 sequence data from a species outside the Rattus or Mus genera, and for the first time from a rodent species endemic to Africa.

  • Shedding dynamics of Morogoro virus, an African arenavirus closely related to Lassa virus, in its natural reservoir host Mastomys Natalensis
    Scientific Reports, 2015
    Co-Authors: Benny Borremans, Raphaël Vossen, Beate Becker-ziaja, Sophie Gryseels, Nelika Hughes, Mats Van Gestel, Natalie Van Houtte, Stephan Günther, Herwig Leirs
    Abstract:

    Arenaviruses can cause mild to severe hemorrhagic fevers. Humans mainly get infected through contact with infected rodents or their excretions, yet little is known about transmission dynamics within rodent populations. Morogoro virus (MORV) is an Old World arenavirus closely related to Lassa virus with which it shares the same host species Mastomys Natalensis . We injected MORV in its host and sampled blood and excretions at frequent intervals. Infection in adults was acute; viral RNA disappeared from blood after 18 days post infection (dpi) and from excretions after 39 dpi. Antibodies were present from 7 dpi and never disappeared. Neonatally infected animals acquired a chronic infection with RNA and antibodies in blood for at least 3 months. The quantified excretion and antibody patterns can be used to inform mathematical transmission models and are essential for understanding and controlling transmission in the natural rodent host populations.

  • gairo virus a novel arenavirus of the widespread Mastomys Natalensis genetically divergent but ecologically similar to lassa and morogoro viruses
    Virology, 2015
    Co-Authors: Sophie Gryseels, Herwig Leirs, Rhodes H. Makundi, Benny Borremans, Stephan Günther, Toni Rieger, Lisa Oestereich, Bart Cuypers, Joelle Gouy De Bellocq
    Abstract:

    Despite its near pan-African range, the Natal multimammate mouse, Mastomys Natalensis, carries the human pathogen Lassa virus only in West Africa, while the seemingly non-pathogenic arenaviruses Mopeia, Morogoro, and Luna have been detected in this semi-commensal rodent in Mozambique/Zimbabwe, Tanzania and Zambia, respectively. Here, we describe a novel arenavirus in M. Natalensis from Gairo district of central Tanzania, for which we propose the name "Gairo virus". Surprisingly, the virus is not closely related with Morogoro virus that infects M. Natalensis only 90km south of Gairo, but clusters phylogenetically with Mobala-like viruses that infect non-M. Natalensis host species in Central African Republic and Ethiopia. Despite the evolutionary distance, Gairo virus shares basic ecological features with the other M. Natalensis-borne viruses Lassa and Morogoro. Our data show that M. Natalensis, carrying distantly related viruses even in the same geographical area, is a potent reservoir host for a variety of arenaviruses.

  • trichuris spp nematoda trichuridae from two rodents Mastomys Natalensis and gerbilliscus vicinus in tanzania
    Journal of Parasitology, 2013
    Co-Authors: Alexis Ribas, Herwig Leirs, Rhodes H. Makundi, Sergi Lopez, Joelle Gouy De Bellocq
    Abstract:

    Abstract:  During a survey of the helminth community of several rodent species in the Morogoro region (Tanzania), Trichuris whipworms (Nematoda: Trichuridae) were found in the ceca of the Natal multimammate mouse, Mastomys Natalensis and a gerbil, Gerbilliscus vicinus (both Rodentia: Muridae). The taxonomic literature regarding Trichuris from African native rodents describes 10 species, but includes few metric and morphologic characters that discriminate between some of the pairs. The whipworms we sampled in Tanzanian Natal multimammate mice and gerbils were morphologically identified, respectively, as Trichuris Mastomysi Verster, 1960 and Trichuris carlieri Gedoelst, 1916 sensu lato, but with characters that overlap or partially overlap with the cosmopolitan Murinae whipworm, Trichuris muris, already reported from several rodents in Africa. To clarify our identification, we sequenced the ITS-1, 5.8S, and ITS-2 ribosomal DNA region of the worms' nuclear genome. The genetic analyses clearly distinguish the...

  • density thresholds for mopeia virus invasion and persistence in its host Mastomys Natalensis
    Journal of Theoretical Biology, 2013
    Co-Authors: J Goyens, Herwig Leirs, Benny Borremans, Jonas Reijniers
    Abstract:

    Well-established theoretical models predict host density thresholds for invasion and persistence of parasites with a density-dependent transmission. Studying such thresholds in reality, however, is not obvious because it requires long-term data for several fluctuating populations of different size. We developed a spatially explicit and individual-based SEIR model of Mopeia virus in multimammate mice Mastomys Natalensis. This is an interesting model system for studying abundance thresholds because the host is the most common African rodent, populations fluctuate considerably and the virus is closely related to Lassa virus but non-pathogenic to humans so can be studied safely in the field. The simulations show that, while host density clearly is important, sharp thresholds are only to be expected for persistence (and not for invasion), since at short time-spans (as during invasion), stochasticity is determining. Besides host density, also the spatial extent of the host population is important. We observe the repeated local occurrence of herd immunity, leading to a decrease in transmission of the virus, while even a limited amount of dispersal can have a strong influence in spreading and re-igniting the transmission. The model is most sensitive to the duration of the infectious stage, the size of the home range and the transmission coefficient, so these are important factors to determine experimentally in the future.

Rhodes H. Makundi - One of the best experts on this subject based on the ideXlab platform.

  • effect of synthetic hormones on reproduction in Mastomys Natalensis
    Journal of Pest Science, 2018
    Co-Authors: Apia W. Massawe, Rhodes H. Makundi, Zhibin Zhang, Ginethon G Mhamphi, Ming Liu, Steven R Belmain
    Abstract:

    Rodent pest management traditionally relies on some form of lethal control. Developing effective fertility control for pest rodent species could be a major breakthrough particularly in the context of managing rodent population outbreaks. This laboratory-based study is the first to report on the effects of using fertility compounds on an outbreaking rodent pest species found throughout sub-Saharan Africa. Mastomys Natalensis were fed bait containing the synthetic steroid hormones quinestrol and levonorgestrel, both singly and in combination, at three concentrations (10, 50, 100 ppm) for 7 days. Consumption of the bait and animal body mass was mostly the same between treatments when analysed by sex, day and treatment. However, a repeated measures ANOVA indicated that quinestrol and quinestrol + levonorgestrel treatments reduced consumption by up to 45%, particularly at the higher concentrations of 50 and 100 ppm. Although there was no clear concentration effect on animal body mass, quinestrol and quinestrol + levonorgestrel lowered body mass by up to 20% compared to the untreated and levonorgestrel treatments. Quinestrol and quinestrol + levonorgestrel reduced the weight of male rat testes, epididymis and seminal vesicles by 60–80%, and sperm concentration and motility were reduced by more than 95%. No weight changes were observed to uterine and ovarian tissue; however, high uterine oedema was observed among all female rats consuming treated bait at 8 and 40 days from trial start. Trials with mate pairing showed there were significant differences in the pregnancy rate with all treatments when compared to the untreated control group of rodents.

  • relationships between seasonal changes in diet of multimammate rat Mastomys Natalensis and its breeding patterns in semi arid areas in tanzania
    Cogent food & agriculture, 2018
    Co-Authors: Emmanuel C M Mlyashimbi, Apia W. Massawe, Rhodes H. Makundi, Mashaka E Mdangi, Joachim Marien, Didas N Kimaro, A J P Tarimo, Moses Isabirye, David Kifumba, Alice Nakiyemba
    Abstract:

    The diet and breeding patterns of Mastomys Natalensis in semi-arid areas of Isimani division, Iringa region, Tanzania were investigated in maize fields and fallow land. The aim was to investigate the influence of diet on breeding patterns of M. Natalensis. Removal trapping was used to capture rodents and analyse diet categories while Capture-mark-release trapping was used to investigate breeding patterns of female M. Natalensis. Mastomys Natalensis comprised 94%of the total capture, and the remaining 6% comprised of six other species. Statistical analysis of food preferences indicated that both vegetative materials and seeds were significantly higher in the overall diet of M. Natalensis compared with other food materials. Significant differences in the proportions of vegetativematerials and seeds were found between seasons (dry, wet), but not between habitats (fallow, maize). There was a clear seasonal pattern in the proportion of reproductively active females with peaks in April and troughs in October. The proportion of vegetative materialswas highest during thewet season and correlated positively with reproductive activity, suggesting that vegetative materials contain certain compounds (e.g. 6-MBOA) that trigger reproductive activity in M. Natalensis. The breeding activity of M. Natalensis in semi-arid areas might, thus, be reduced by limiting access to fresh vegetative food (e.g. young sprouting grass).

  • polymorphism in vkorc1 gene of natal multimammate mice Mastomys Natalensis in tanzania
    Journal of Heredity, 2015
    Co-Authors: Sophie Gryseels, Herwig Leirs, Rhodes H. Makundi, Joa Lle Goa Y De Bellocq
    Abstract:

    Resistance of rodents to anticoagulant rodenticides has emerged in several areas across the world. Single nucleotide mutations in the vkorc1 gene have been shown to elicit various levels of anticoagulant resistance, and these mutations are prevalent in several Rattus and Mus musculus populations. In sub-Saharan Africa, the Natal multimammate mouse, Mastomys Natalensis, is one of the most damaging pests to crops, and anticoagulant poisons such as bromadiolone are frequently used to control these rodents in agricultural fields. Here, we investigate if vkorc1 shows any polymorphism in natural populations of M. Natalensis. We sequenced the third exon of vkorc1 of 162 M. Natalensis captured from 14 different agricultural sites in Morogoro Region, Tanzania. In addition to 6 SNPs in the noncoding flanking region, we detected 3 nonsynonymous SNPs in this exon: 10 animals (6.2%) carried a Leu108Val variant, 2 animals (1.2%) an Ala140Thr variant, and 1 animal (0.6 %) an Arg100His variant, all 3 in heterozygous form. Ala140Thr is just one residue from a mutation known to be involved in anticoagulant resistance in Rattus and Mus. While in vitro or in vivo experiments are needed to link vkorc1 genetic polymorphisms to level of VKOR activity and anticoagulant susceptibility, our results suggest that M. Natalensis individuals may vary in their response to anticoagulant rodenticides. This is the first vkorc1 sequence data from a species outside the Rattus or Mus genera, and for the first time from a rodent species endemic to Africa.

  • gairo virus a novel arenavirus of the widespread Mastomys Natalensis genetically divergent but ecologically similar to lassa and morogoro viruses
    Virology, 2015
    Co-Authors: Sophie Gryseels, Herwig Leirs, Rhodes H. Makundi, Benny Borremans, Stephan Günther, Toni Rieger, Lisa Oestereich, Bart Cuypers, Joelle Gouy De Bellocq
    Abstract:

    Despite its near pan-African range, the Natal multimammate mouse, Mastomys Natalensis, carries the human pathogen Lassa virus only in West Africa, while the seemingly non-pathogenic arenaviruses Mopeia, Morogoro, and Luna have been detected in this semi-commensal rodent in Mozambique/Zimbabwe, Tanzania and Zambia, respectively. Here, we describe a novel arenavirus in M. Natalensis from Gairo district of central Tanzania, for which we propose the name "Gairo virus". Surprisingly, the virus is not closely related with Morogoro virus that infects M. Natalensis only 90km south of Gairo, but clusters phylogenetically with Mobala-like viruses that infect non-M. Natalensis host species in Central African Republic and Ethiopia. Despite the evolutionary distance, Gairo virus shares basic ecological features with the other M. Natalensis-borne viruses Lassa and Morogoro. Our data show that M. Natalensis, carrying distantly related viruses even in the same geographical area, is a potent reservoir host for a variety of arenaviruses.

  • trichuris spp nematoda trichuridae from two rodents Mastomys Natalensis and gerbilliscus vicinus in tanzania
    Journal of Parasitology, 2013
    Co-Authors: Alexis Ribas, Herwig Leirs, Rhodes H. Makundi, Sergi Lopez, Joelle Gouy De Bellocq
    Abstract:

    Abstract:  During a survey of the helminth community of several rodent species in the Morogoro region (Tanzania), Trichuris whipworms (Nematoda: Trichuridae) were found in the ceca of the Natal multimammate mouse, Mastomys Natalensis and a gerbil, Gerbilliscus vicinus (both Rodentia: Muridae). The taxonomic literature regarding Trichuris from African native rodents describes 10 species, but includes few metric and morphologic characters that discriminate between some of the pairs. The whipworms we sampled in Tanzanian Natal multimammate mice and gerbils were morphologically identified, respectively, as Trichuris Mastomysi Verster, 1960 and Trichuris carlieri Gedoelst, 1916 sensu lato, but with characters that overlap or partially overlap with the cosmopolitan Murinae whipworm, Trichuris muris, already reported from several rodents in Africa. To clarify our identification, we sequenced the ITS-1, 5.8S, and ITS-2 ribosomal DNA region of the worms' nuclear genome. The genetic analyses clearly distinguish the...

R. Rudolph - One of the best experts on this subject based on the ideXlab platform.

  • capillaria hepatica infektion der Mastomys Natalensis pathologische veranderungen der leber und milz nach infektionen mit embryonierten und rontgenattenuierten eiern
    Journal of Veterinary Medicine Series B-infectious Diseases and Veterinary Public Health, 2010
    Co-Authors: Horst Zahner, R. Rudolph
    Abstract:

    Zusammenfassung Nach Infektionen von Mastomys Natalensis mit embryonierten und rontgenattenuierten Eiern von Capillaria hepatica wurden die Veranderungen der Leber und der Milz uber einen Zeitraum von 102 Tagen p. i. untersucht. Die histopathologisch nachweisbaren Veranderungen sowie die Unterschiede im relativen Leber- und Milzgewicht waren nach Infektionen mit embryonierten Eiern am deutlichsten ausgepragt und traten abgestuft mit zunehmender Strahlendosis weniger ausgepragt und z. T. mit zeitlicher Verzogerung nach Infektionen mit rontgenattenuierten Eiern auf. Die histologische Verlaufsuntersuchung zeigte eine dynamische, vom Stadium des Parasiten bzw. der Erkrankung abhangige Entwicklung, in der akute Herdveranderungen zu granulomatosen und regenerativen Reaktionen im Leberparenchym fuhrten und Veranderungen im Glissonbereich auftraten. Die Reaktionen fuhrten zu bzw. waren vergesellschaftet mit anfanglichem Blutreichtum und spaterem proliferativem Umbau der Milz. Die Veranderungen liesen sich mit fruheren Beobachtungen zur Pathophysiologie der C. hepatica-Infektion korrelieren. Die Rolle der Eier bei der Granulombildung wird im Zusammenhang mit weiteren immunologischen Untersuchungen diskutiert. Summary Capillaria hepatica infection of Mastomys Natalensis: Pathological alterations in liver and spleen after infections with embryonated eggs and x-irradiated eggs The alterations in liver and spleen of Mastomys Natalensis were followed over a period of 102 days after infections with embryonated eggs and embryonated, x-irradiated eggs of Capillaria hepatica. Increases of the relative weights of liver and spleen and histopathological alterations were most marked after infections with untreated embryonated eggs. In histological investigations a dynamic development could be demonstrated which depended on the stage of the parasites and the disease, respectively. Acute, focal alterations led to granulomatous and regenerative reactions of the liver parenchyma which were accompanied by alterations of the glisson area. The reactions of the spleen were initially characterized by a marked increase in blood content, followed by a proliferation. Results of earlier investigations on the pathophysiology of the C. hepatica infection could be related to alterations observed in this study. The role of the eggs in the granuloma formation is discussed in connection with further immunological investigations. Resume Infection a Capillaria hepatica chez Mastomys Natalensis: Lesions pathologiques du foie et de la rate apres des infections avec des oeufs embryonnes et attenues aux rayons X Les lesions du foie et de la rate chez des Mastomys Natalensis ont ete examinees durant un laps de temps de 102 jours apres des infections avec des oeufs embryonnees et attenues aux rayons X de Capillaria hepatica. Les lesions histopathologiques mises en evidence ainsi que les differences dans le poids relatif du foie et de la rate furent le plus etendues avec des oeufs embryonnes et diminuerent progressivement avec des doses augmentees de rayons X; un ralentissement temporaire fut observe apres des infections avec des oeufs attenues aux rayons X. L'examen histologique continu a montre un developpement dynamique dependant du stade du parasite et de la maladie conduisant a des reactions granulomateuses et de regeneration dans les lesions localisees aiguěs du parenchyme hepatique et a des lesions dans la region de Glisson. Les reactions furent concentrees dans la rate avec une congestion sanguine initiale suivie d'un processus proliferatif. Les lesions furent en correlation avec des observations precedentes sur la pathophysiologie de C. hepatica. Le role des oeufs dans la formation granulomateuse est discutee en fonction d'autres recherches immunologiques. Resumen Infestacion por Capillaria hepatica en la Mastomys Natalensis: modificaciones patologicas en el higado y bazo tras infestaciones con huevos embrionados y atenuados por rayos Roentgen Tras infestaciones de Mastomys Natalensis con huevos embrionados y atenuados mediante rayos X de Capillaria hepatica se examinaron las modificaciones habidas en el higado y bazo a lo largo de un espacio de tiempo de 102 dias p. i. Las modificaciones histopatologicas identificables asi como las diferencias en los pesos relativos de higado y bazo se hallaban acentuadas con claridad maxima tras infestaciones con huevos embrionados y aparecian graduadas de forma menos manifiesta con dosis crecientes de rayos X y en parte con dilacion temporal tras infestacion con huevos atenuados por irradiacion X. Mostraba el examen del curso histologico un desarrollo dinamico dependiente del estadio del parasito resp. de la enfermedad, en el cual modificaciones focales agudas conducian a reacciones granulomatosas y regenerativas en el parenquima hepatico, apareciendo modificaciones en el ambito de Glisson. Las reacciones conducian a resp. se hallaban asociadas a hiperemia inicial y mas adelante a una reorganizacion proliferativa del bazo. Se pudieron correlacionar las modificaciones con observaciones anteriores relativas a la fisiopatologia de la infestacion por C. hepatica. Se discute el papel de los huevos en la granulomagenesis en relacion con ulteriores estudios inmunologicos.

  • Capillaria hepatica‐Infektion der Mastomys Natalensis: Pathologische Veränderungen der Leber und Milz nach Infektionen mit embryonierten und röntgenattenuierten Eiern*
    Journal of Veterinary Medicine Series B-infectious Diseases and Veterinary Public Health, 2010
    Co-Authors: Horst Zahner, R. Rudolph
    Abstract:

    Zusammenfassung Nach Infektionen von Mastomys Natalensis mit embryonierten und rontgenattenuierten Eiern von Capillaria hepatica wurden die Veranderungen der Leber und der Milz uber einen Zeitraum von 102 Tagen p. i. untersucht. Die histopathologisch nachweisbaren Veranderungen sowie die Unterschiede im relativen Leber- und Milzgewicht waren nach Infektionen mit embryonierten Eiern am deutlichsten ausgepragt und traten abgestuft mit zunehmender Strahlendosis weniger ausgepragt und z. T. mit zeitlicher Verzogerung nach Infektionen mit rontgenattenuierten Eiern auf. Die histologische Verlaufsuntersuchung zeigte eine dynamische, vom Stadium des Parasiten bzw. der Erkrankung abhangige Entwicklung, in der akute Herdveranderungen zu granulomatosen und regenerativen Reaktionen im Leberparenchym fuhrten und Veranderungen im Glissonbereich auftraten. Die Reaktionen fuhrten zu bzw. waren vergesellschaftet mit anfanglichem Blutreichtum und spaterem proliferativem Umbau der Milz. Die Veranderungen liesen sich mit fruheren Beobachtungen zur Pathophysiologie der C. hepatica-Infektion korrelieren. Die Rolle der Eier bei der Granulombildung wird im Zusammenhang mit weiteren immunologischen Untersuchungen diskutiert. Summary Capillaria hepatica infection of Mastomys Natalensis: Pathological alterations in liver and spleen after infections with embryonated eggs and x-irradiated eggs The alterations in liver and spleen of Mastomys Natalensis were followed over a period of 102 days after infections with embryonated eggs and embryonated, x-irradiated eggs of Capillaria hepatica. Increases of the relative weights of liver and spleen and histopathological alterations were most marked after infections with untreated embryonated eggs. In histological investigations a dynamic development could be demonstrated which depended on the stage of the parasites and the disease, respectively. Acute, focal alterations led to granulomatous and regenerative reactions of the liver parenchyma which were accompanied by alterations of the glisson area. The reactions of the spleen were initially characterized by a marked increase in blood content, followed by a proliferation. Results of earlier investigations on the pathophysiology of the C. hepatica infection could be related to alterations observed in this study. The role of the eggs in the granuloma formation is discussed in connection with further immunological investigations. Resume Infection a Capillaria hepatica chez Mastomys Natalensis: Lesions pathologiques du foie et de la rate apres des infections avec des oeufs embryonnes et attenues aux rayons X Les lesions du foie et de la rate chez des Mastomys Natalensis ont ete examinees durant un laps de temps de 102 jours apres des infections avec des oeufs embryonnees et attenues aux rayons X de Capillaria hepatica. Les lesions histopathologiques mises en evidence ainsi que les differences dans le poids relatif du foie et de la rate furent le plus etendues avec des oeufs embryonnes et diminuerent progressivement avec des doses augmentees de rayons X; un ralentissement temporaire fut observe apres des infections avec des oeufs attenues aux rayons X. L'examen histologique continu a montre un developpement dynamique dependant du stade du parasite et de la maladie conduisant a des reactions granulomateuses et de regeneration dans les lesions localisees aiguěs du parenchyme hepatique et a des lesions dans la region de Glisson. Les reactions furent concentrees dans la rate avec une congestion sanguine initiale suivie d'un processus proliferatif. Les lesions furent en correlation avec des observations precedentes sur la pathophysiologie de C. hepatica. Le role des oeufs dans la formation granulomateuse est discutee en fonction d'autres recherches immunologiques. Resumen Infestacion por Capillaria hepatica en la Mastomys Natalensis: modificaciones patologicas en el higado y bazo tras infestaciones con huevos embrionados y atenuados por rayos Roentgen Tras infestaciones de Mastomys Natalensis con huevos embrionados y atenuados mediante rayos X de Capillaria hepatica se examinaron las modificaciones habidas en el higado y bazo a lo largo de un espacio de tiempo de 102 dias p. i. Las modificaciones histopatologicas identificables asi como las diferencias en los pesos relativos de higado y bazo se hallaban acentuadas con claridad maxima tras infestaciones con huevos embrionados y aparecian graduadas de forma menos manifiesta con dosis crecientes de rayos X y en parte con dilacion temporal tras infestacion con huevos atenuados por irradiacion X. Mostraba el examen del curso histologico un desarrollo dinamico dependiente del estadio del parasito resp. de la enfermedad, en el cual modificaciones focales agudas conducian a reacciones granulomatosas y regenerativas en el parenquima hepatico, apareciendo modificaciones en el ambito de Glisson. Las reacciones conducian a resp. se hallaban asociadas a hiperemia inicial y mas adelante a una reorganizacion proliferativa del bazo. Se pudieron correlacionar las modificaciones con observaciones anteriores relativas a la fisiopatologia de la infestacion por C. hepatica. Se discute el papel de los huevos en la granulomagenesis en relacion con ulteriores estudios inmunologicos.

  • capillaria hepatica infektion der Mastomys Natalensis die abhangigkeit der granulombildung um intravenos injizierte eier vom stadium der infektion
    Journal of Veterinary Medicine Series B-infectious Diseases and Veterinary Public Health, 2010
    Co-Authors: Horst Zahner, E. Geyer, R. Rudolph
    Abstract:

    Zusammenfassung Mastomys Natalensis wurden durch eine intravenose Injektion frisch isolierter Capillaria hepatica-Eier belastet, nachdem sie 35 Tage vorher durch intraperitoneale Injektion frisch isolierter Eier sensibilisiert oder 6–300 Tage vorher mit jeweils 300 embryonierten Eiern von C. hepatica infiziert worden waren. Nicht infizierte Tiere dienten als Kontrollen. Bei der 2, 4 und 8 Tage nach der Belastungsinjektion durchgefuhrten histologischen Beurteilung der in der Lunge um die Eier aufgetretenen zellularen Reaktionen wurde eine von Beginn an uberwiegend mononukleare und zwischen dem 2. und 8. Tag nach der Injektion zunehmende Reaktion um die in den Lungenkapillaren lokalisierten Eier beobachtet. Bei den 35 Tage vor der Belastung mit frisch isolierten Eiern sensibilisierten Tieren kam es zu starker Granulombildung. Schwachere Reaktionen traten i. d. R. dann auf, wenn die Belastungsinjektion in der Prapatenz, in der Postpatenz oder bei nicht infizierten Tieren durchgefuhrt wurde. Keine oder nur eine geringe Granulombildung wurde beobachtet, wenn die Belastungsinjektion wahrend der patenten Phase einer C. hepatica-Infektion erfolgte. Die moglichen Ursachen und Konsequenzen der verminderten immunologischen Reaktivitat C. hepatica-infizierter M. Natalensis gegen frisch isolierte, intravenos injizierte Eier von C. hepatica innerhalb der Patenz werden diskutiert. Summary Capillaria hepatica infection of Mastomys Natalensis: Dependence of granuloma formation around intraveneously injected eggs on the stage of infection Groups of Mastomys Natalensis sensitized 35 days previously by an intraperitoneal injection of freshly isolated eggs, or 6–300 days previously infected by oral administration of embryonated eggs, and non-infected controls were challenged by an intravenous injection of freshly isolated C. hepatica-eggs. 2, 4 and 8 days later the cellular reactions around the eggs located in the capillaries of the lungs were histologically investigated. A mainly mononuclear infiltration, increasing up to 8 days after injection, led to a marked granuloma formation around the eggs in the presensitized group. Weaker reactions occurred usually when the eggs were injected during prepatency, after patency, or in non-infected animals. Markedly weaker reactions or a lack of reactivity were observed when the eggs had been injected during the patency of an existing C. hepatica infection. Possible reasons and consequences of a reduced immunological reactivity of M. Natalensis against C. hepatica eggs during patency and the lack of sensitization in the course of C. hepatica infections are discussed. Resume Infection a Capillaria hepatica chez Mastomys Natalensis: Dependance du stade de l'infection pour la formation d'un granulome autour des oeufs injectes par voie intraveineuse Des Mastomys Natalensis ont ete infectes par injection intraveineuse avec des oeufs de Capillaria hepatica fraichement isoles apres avoir ete sensibilises 35 jours auparavant par une injection intraperitoneale d'oeufs fraichement isoles ou infectes selon le cas avec 300 oeufs embryonnes de C. hepatica 6–300 jours auparavant. Des animaux non infectes ont servi de controles. Les examens histologiques effectues 2, 4 et 8 jours apres l'injection ont montre des reactions cellulaires dans les poumons autour des oeufs qui furent principalement mononucleates au debut avec une reaction augmentee le 2e et le 8e jour apres l'injection autour des oeufs localises dans les capillaires pulmonaires. La formation granulomateuse fut plus forte chez les animaux sensibilises 35 jours auparavant avec des oeufs fraichement isoles. Des reactions plus faibles ont ete enregistrees en general lorsque l'injection infectieuse avait ete realisee dans une phase prepatente, postpatente ou chez des animaux non infectes. Aucune ou une tres faible formation granulomateuse a ete observee si l'injection avait lieu durant la phase patente d'une infection a C. hepatica. Les causes possibles et les consequences de la reaction immunologique diminuee de M. Natalensis infecte par C. hepatica vis-a-vis d'oeufs fraichement isoles de C. hepatica injectes par voie intraveineuse durant la phase patente sont discutees. Resumen Infestacion por Capillaria hepatica en la Mastomys Natalensis: Dependencia de la granulomagenesis alrededor de huevos inyectados intravenosamente del estadio de infestacion Mastomys Natalensis se recargaron mediante una inyeccion intravenosa de huevos Capillaria hepatica de aislamiento reciente, despues de que se sensibilizaron 35 dias antes, por medio de una inyeccion intraperitoneal a base de huevos aislados fescos o infestandose de 6–300 dias antes con cada vez 300 huevos embrionados de C. hepatica. Animales no infestados hacian las veces de testigos. En la apreciacion histologica, llevada a cabo, 2, 4 y 8 dias despues de la inyeccion de recargo, de la reaccion celular pulmonar alrededor de los huevos se observo una reaccion mononuclear en su mayoria desde el principio, la cual aumentaba entre los dias 2° a 8° despues de la inyeccion, alrededor de los huevos localizados en los capilares pulmonares. En los animales sensibilizados 35 dias antes del recargo con huevos aislados frescos, se registro una formacion intensa de granulomas. Solian aparecer reacciones mis debiles cuando la inyeccion de recargo habia sido efectuada en la prepatencia, en la postpatencia o en animales no infestados. No se observo granulomagenesis o la misma era solo muy escasa cuando la inyeccion de recargo acontecia durante la fase patente de una infestacion por C. hepatica. Se discuten las causas y consecuencias posibles de la reactividad inmunologica disminuida de M. Natalensis infestados con C. hepatica frente a huevos aislados frescos, inyectados por via intravenosa, de C. hepatica dentro de la patencia.

  • pathologische anatomie und histologie von spontanen epithelialen hauttumoren bei Mastomys Natalensis
    Journal of Veterinary Medicine Series A-physiology Pathology Clinical Medicine, 2010
    Co-Authors: R. Rudolph, W Thiel
    Abstract:

    Zusammenfassung Bei 20 Mastomys Natalensis wurden 54 spontane Neubildungen in der Haut gefunden, welche in 4 verhornende Plattenepithelkarzinome, 8 exophytische keratotische Papillome, 12 sogenannte Keratoakanthome, 5 Epithelproliferationen und 25 Mischformen eingeteilt werden; letztere enthalten 2 Plattenepithelkarzinome, 20 Papillome, 25 sogenannte Keratoakanthome und 15 Epithelproliferationen. Die makroskopischen und histologischen Merkmale werden beschrieben. Unter Hinweis auf die Virusdarstellungen und erfolgreichen experimentellen Tumorinduktionen wird fur die Hauttumoren bei Mastomys Natalensis eine Virusatiologie angenommen. Die Pathogenese ist durch Proliferation epithelialer Hautzellen gekennzeichnet, welche sich zu Papillom und sogenanntem Keratoakanthom weiterentwickeln und auf der Grundlage vor allem letzterer zum Plattenepithelkarzinom fuhren kann. In der Diskussion werden Gemeinsamkeiten und Unterschiede zu spontanem Keratoakanthom des Menschen und experimentell-chemisch induziertem Keratoakanthom verschiedener Versuchstierspezies diskutiert. Summary Pathological anatomy and histology of spontaneous epithelial skin tumours in Mastomys Natalensis In 20 Mastomys Natalensis 54 spontaneous skin tumours were found, divided into 4 keratinizing squamous epithelial carcinomas, 8 exophytic keratotic papillomas, 12 so-called keratoacanthomas, 5 epithelial proliferations and 25 mixed forms comprising 2 squamous epithelial carcinomas, 20 papillomas, 25 so-called keratoacanthomas, and 15 epithelial proliferations. The macroscopic and histological characters of the various tumours are described. On the basis of demonstration of virus and successful induction of tumours it is concluded that skin tumours in Mastomys Natalensis are of viral aetiology. The pathogenesis is characterized by proliferation of epithelial skin cells which develop further into papilloma and so-called keratoacanthoma and from the latter can develop into squamous cell carcinoma. Similarities and differences between spontaneous keratoacanthoma in man and experimental chemical-induced keratoacanthoms in various animal species are discussed. Resume Anatomie pathologique et histologie de ***tumours cutanees epitheliales spontanees chez Mastomys Natalensis 54 neoformations cutanees spontanees ont ete trouvees chez 20 Mastomys Natalensis qui se repartissaient en 4 carcinomes de l'epithelium pavimenteux corne, 8 papillomes exophytiques keratotiques, de 12 keratoacanthomes ainsi denommes, de 5 proliferations epitheliales et de 25 formes mixtes; ces derniers comportaient 2 carcinomes de l'epithelium pavimenteux, 20 papillomes, 25 keratoacanthomes et 15 proliferations epitheliales. On decrit les particularites macroscopiques et histologiques. Une etiologie virale a ete admise pour les tumeurs cutanees chez Mastomys Natalensis a la suite de mise en evidence de virus et d'inductions tumorales experimentales. La pathogenese est reconnaissable a la proliferation des cellules cutanees epitheliales qui peut se developper en papillome et keratoacanthome, et qui sur la base avant tout de ces derniers peut conduire a un carcinome de l'epithelium pavimenteux. On discute les points communs et les differences entre le keratoacanthome spontane chez l'homme et le keratoacantome induit chimiquement en experience chez differentes especes animales. Resumen Anatomo e histopatologia de tumores cutaneos epiteliales espontaneos en Mastomys Natalensis En 20 Mastomys Natalensis se hallaron 54 neoformaciones espontaneas en la piel, las cuales se reparten en 4 carcinomas de epitelio pavimentoso queratinizante, 8 papilomas queratosicos exofiticos, 12 llamados queratoacantomas, 5 proliferaciones epiteliales y 25 formas mixtas; estas ultimas comprenden 2 carcinomas de epitelio pavimentoso, 20 papilomas, 25 llamados queratoacantomas y 15 proliferaciones epiteliales. Se describen las caracteristicas macroscopicas e histopatologicas. Bajo remision a las presentaciones de virus e inducciones experimentales eficaces, se admite una etiologia virosica para los tumores cutaneos en Mastomys Natalensis. La patogenia se halla caracterizada por proliferaciones de celulas cutaneas epiteliales, las cuales siguen desarrollan-dose hasta papiloma y el llamado queratoacantoma y pueden conducir sobre la base ante todo de este ultimo a carcinoma de epitelio plano. En la discusion se citan las comunidades y diferencias con el queratoacantoma espontaneo del hombre y el queratoacantoma quimico-experimental inducido en varias especies animales de ensayo.

  • induktion von epidermalem tumorwachstum in der haut von Mastomys Natalensis durch ubertragung virushaltigen tumorgewebes eines plattenepithelkarzinoms
    Journal of Veterinary Medicine Series B-infectious Diseases and Veterinary Public Health, 2010
    Co-Authors: R. Rudolph, Hanspeter Muller
    Abstract:

    Zusammenfassung Durch ubertragung von virus- und zellhaltigem Gewebe aus einem Plattenepithelkarzinom auf die enthaarte und skarifizierte Haut der Lendenregion von 7 Wochen alten Tieren der gleichen Spezies (Mastomys Natalensis, GRA Giesen) gelingt in etwa 50% der Empfanger die Entstehung neuer Tumoren am Applikationsort. Es wird angenommen, das eine Tumorinduktion erfolgt. Aus den experimentellen Neoplasien ist regelmasig das ebenfalls in den Spontantumoren enthaltene Virus darstellbar, welches vorlaufig der Papovavirus-Gruppe zugeordnet wird. Auch bei den experimentellen Tumoren erfolgt auf der Grundlage einer Epidermisproliferation ein fortschreitendes Wachstum ohne Anzeichen einer Spontaninvolution, wobei die histologischen Bilder der bisher untersuchten Neoplasien vor allem denjenigen der spontanen sogenannten Keratoakanthome von Mastomys Natalensis gleichen. In zwei Fallen liegt weiteres Tiefenwachstum in die Muskulatur vor. Summary Induction of epidermal tumour growth in the skin of Mastomys Natalensis by transfer of virus-containing tumour tissue from a squamous cell carcinoma Transfer of tissue containing cells and virus from a squamous cell carcinoma to the depilated and scarified skin of the lumbar region of 7 week old Mastomys Natalensis (GRA Giessen) succeeded in about 50% of the recipients in producing new tumours at the application site. It is assumed that tumour induction took place. From the experimentally produced neoplasms the virus present in the original tumour was regularly identified and was formally classed in the papova virus group. In the experimental tumours there occurred, on the basis of an epidermal proliferation, a progressive growth without signs of spontaneous involution, whereby the histological picture of the neoplasms so far induced resembled most closely that of the spontaneous so-called keratoacanthoma of Mastomys Natalensis. In two cases there was further growth into the depth of the musculature. Resume Iuduction de la croissance des tumeurs epidermales sur la peau de Mastomys Natalensis par transplantation de tissus contenant des virus d'un carcinoma de l'epithelium pavimenteux De nouvelles tumeurs sont apparues sur le champ d'application dans environ 50% des cas lors de transmission de tissus contenant virus et cellules a partir d'un carcinome de l'epithelium pavimenteux sur la peau rasee et scarifyee de la region lombaire chez des animaux de la meme espece (Mastomys Natalensis, GRA Giesen) âges de 7 semaines. Une induction tumorale a ete admise. Un virus, appartenant provisoirement au groupe des Papovavirus, fut regulierement observe dans les neoplasies experimentales comme dans les tumeurs spontanees. Une croissance progressive sans signes d'une involution spontanee continua sur la base d'une proliferation de l'epiderme egalement dans les tumeurs experimentales et l'image histologique des neoplasies examinees jusqu'a maintenant fut comparable a celle des keratoacanthomes de Mastomys Natalensis. Une croissance en profondeur dans la musculature fut constatee dans deux cas. Resumen Induccion de crecemiento tumoral epidermico en la piel de Mastomys Natalensis mediante la transmision de tejido conteniendo virus y celulas de un carcinoma planocelular Mediante la transmision de tejido que contiene virus y celulas de un carcinoma planocelular sobre la piel depilada y escarificada de la region lumbar de animales de 7 semanas de edad de la misma especie (Mastomys Natalensis, GRA Giesen), se logra la formacion de nuevos tumores en el lugar de aplicacion en el 50% aprox. de los receptores. Se supone que acontece una induccion tumoral. De las neoplasias experimentales se puede revelar la presencia regular del virus contenido tambien en los tumores espontaneos, el cual se encuadra de forma provisional en el grupo de virus Papova. Tambien acontece en los tumores experimentales sobre la base de una proliferacion epidermica un crecimiento progresivo sin signos de una involucion espontanea, asemejandose las imagenes histopatologicas de las neoplasias examinadas hasta ahora, ante todo, a las de los llamados queratoacantomas espontaneos en los Mastomys Natalensis. Se registro en dos casos un crecimiento profundo adicional dentro de la musculatura.

Emilie Lecompte - One of the best experts on this subject based on the ideXlab platform.

  • A mitochondrial phylogeographic scenario for the most widespread African rodent, Mastomys Natalensis
    Biological Journal of the Linnean Society, 2013
    Co-Authors: Paolo Colangelo, Herwig Leirs, Gauthier Dobigny, Erik Verheyen, Caroline Tatard, Christiane Denys, Jean-marc Duplantier, Carine Brouat, Laurent Granjon, Emilie Lecompte
    Abstract:

    In order to evaluate the contribution of geological, environmental, and climatic changes to the spatial distribution of genetic variation of Mastomys Natalensis, we analysed cytochrome b sequences from the whole distribution area of the species to infer its phylogeographic structure and historical demography. Six well-supported phylogroups, differentiated during the Pleistocene, were evidenced. No significant correlation between genetic and geographic distances was found at the continental scale, and the geographic distributions of the observed phylogroups have resulted from extensive periods of isolation caused by the presence of putative geographic and ecological barriers. The diversification events were probably influenced by habitat contraction/expansion cycles that may have complemented topographic barriers to induce genetic drift and lineage sorting.According to our results, we propose a scenario where climate-driven processes may have played a primary role in the differentiation among phylogroups.

  • reproductive characteristics of Mastomys Natalensis and lassa virus prevalence in guinea west africa
    Vector-borne and Zoonotic Diseases, 2008
    Co-Authors: Elisabeth Fichetcalvet, Emilie Lecompte, Stephane Daffis, Lamine Koivogui, Jan Ter Meulen
    Abstract:

    We recently reported increased prevalence of Lassa virus (LASV) infection in Mastomys Natalensis during the rainy season in Guinea, West Africa. Here, the association of LASV prevalence with fecundity, fertility, and the age structure of the rodent population was analyzed using data from the previous study. The animals reproduced throughout the year, but highest fecundity was observed during the rainy season. Accordingly, the rodent population was aged at the beginning and young at the end of the rainy season. Lassa virus infection was observed in all age groups, including the very young, which is compatible with vertical transmission. However, since the prevalence of infection showed a trend with increasing age in the younger age groups, horizontal transmission by yet unknown mechanisms may also play a role in LASV transmission. Multivariate analysis did not show an association of LASV prevalence with any demographic variable studied. Rodent behavior influencing virus transmissibility and contaminated environment may therefore be responsible for spatial and seasonal variations in LASV prevalence in M. Natalensis.

  • Mastomys Natalensis and lassa fever west africa
    Emerging Infectious Diseases, 2006
    Co-Authors: Emilie Lecompte, Elisabeth Fichetcalvet, Stephane Daffis, Kekoura Koulemou, Oumar Sylla, Fode Kourouma, Amadou Dore, Barre Soropogui, V M Aniskin, Bernard Allali
    Abstract:

    PCR screening of 1,482 murid rodents from 13 genera caught in 18 different localities of Guinea, West Africa, showed Lassa virus infection only in molecularly typed Mastomys Natalensis. Distribution of this rodent and relative abundance compared with M. erythroleucus correlates geographically with Lassa virus seroprevalence in humans.

  • polymorphism of the age population structure of two wild Mastomys Natalensis rodentia muridae tanzanian habitat samples a multicriteria comparison
    Mammalia, 2006
    Co-Authors: Aude Lalis, Rhodes H. Makundi, Emilie Lecompte, Raphael Cornette, Sybille Moulin, Robert S Machangu, Vladimir Aniskine, Christiane Denys
    Abstract:

    Dans le but d'etudier la structure d'âge de deux echantillons de Mastomys Natalensis en periode seche, nous avons utilise trois differentes approches: la masse corporelle, les stades d'usure dentaire et le poids sec du cristallin. Les trois techniques d'estimation de l'âge donnent approximativement la presence d'une majorite d'individus juveniles pur les 2 echantillons. Le test de Fisher n'a pas montre de difference significative pour la variable «sexe» entre les deux echantillons. Ces resultats s'accordent avec le cycle de vie connu de Mastomys Natalensis et semblent confirmer une forte potentialite de dispersion de l'espece. En outre, dans le contexte de faibles precipitations de l'hiver 2003, nos donnees revelent des differences d'âge entre les echantillons provenant de deux habitats de types differents. Dans le cadre de cette etude, la variable la mieux correlee a l'âge pour les premieres classes d'âge est le poids sec du cristallin. La technique de la masse corporelle semble etre la mieux adaptee aux conditions d'echantillonnage (echantillons de faible taille, periode de reproduction) et a ses objectifs (determination de l'âge instantane d'echantillons). Cette etude montre que meme a partir de donnees restreintes, qu'avec de simples precautions lors des manipulations et une comprehension claire des limites methodologiques pour chaque technique, il est possible d'obtenir des premiers resultats informatifs. Completes par des donnees sur la morphologie et la variabilite moleculaire, ces resultats pourraient permettre de mieux apprehender les processus de differenciation chez le modele M. Natalensis.

Joelle Gouy De Bellocq - One of the best experts on this subject based on the ideXlab platform.

  • dhati welel virus the missing mammarenavirus of the widespread Mastomys Natalensis
    Journal of Vertebrate Biology, 2020
    Co-Authors: Joelle Gouy De Bellocq, Anna Bryjova, Aleksey A Martynov, L A Lavrenchenko
    Abstract:

    The Natal multimammate mouse, Mastomys Natalensis, occurs throughout sub-Saharan Africa. Mitochondrial phylogenetics indicate this species was fragmented during the Pleistocene, forming six matrilineage phylogroups: A-I, A-II, A-III, B-IV, B-V, B-VI with distinct ranges. All except the A-III lineage are identified as natural reservoirs of mammarenaviruses. M. Natalensis A-III is found in western Ethiopia and is the only lineage reported in the country. While screening 203 small mammal samples from Dhati Welel National Park for mammarenaviruses, we detected mammarenavirus RNA in nine samples, eight from M. Natalensis and one from M. awashensis. A sequence similarity search and phylogenetic analysis confirmed the M. Natalensis mitochondrial DNA belongs to the A-III lineage. We characterised the complete virus genome, which showed typical mammarenavirus organisation. Phylogenetic analysis indicated it clusters with Gairo virus found in M. Natalensis B-IV in Tanzania, while showing sufficient divergence from other mammarenaviruses to be considered as a new species, for which we proposed the name Dhati Welel. Additional sampling in the M. Natalensis A-III phylogeographic range should help determine whether the detection of the virus in M. awashensis represents a local spill-over or if the virus circulates in both Mastomys species.

  • gairo virus a novel arenavirus of the widespread Mastomys Natalensis genetically divergent but ecologically similar to lassa and morogoro viruses
    Virology, 2015
    Co-Authors: Sophie Gryseels, Herwig Leirs, Rhodes H. Makundi, Benny Borremans, Stephan Günther, Toni Rieger, Lisa Oestereich, Bart Cuypers, Joelle Gouy De Bellocq
    Abstract:

    Despite its near pan-African range, the Natal multimammate mouse, Mastomys Natalensis, carries the human pathogen Lassa virus only in West Africa, while the seemingly non-pathogenic arenaviruses Mopeia, Morogoro, and Luna have been detected in this semi-commensal rodent in Mozambique/Zimbabwe, Tanzania and Zambia, respectively. Here, we describe a novel arenavirus in M. Natalensis from Gairo district of central Tanzania, for which we propose the name "Gairo virus". Surprisingly, the virus is not closely related with Morogoro virus that infects M. Natalensis only 90km south of Gairo, but clusters phylogenetically with Mobala-like viruses that infect non-M. Natalensis host species in Central African Republic and Ethiopia. Despite the evolutionary distance, Gairo virus shares basic ecological features with the other M. Natalensis-borne viruses Lassa and Morogoro. Our data show that M. Natalensis, carrying distantly related viruses even in the same geographical area, is a potent reservoir host for a variety of arenaviruses.

  • trichuris spp nematoda trichuridae from two rodents Mastomys Natalensis and gerbilliscus vicinus in tanzania
    Journal of Parasitology, 2013
    Co-Authors: Alexis Ribas, Herwig Leirs, Rhodes H. Makundi, Sergi Lopez, Joelle Gouy De Bellocq
    Abstract:

    Abstract:  During a survey of the helminth community of several rodent species in the Morogoro region (Tanzania), Trichuris whipworms (Nematoda: Trichuridae) were found in the ceca of the Natal multimammate mouse, Mastomys Natalensis and a gerbil, Gerbilliscus vicinus (both Rodentia: Muridae). The taxonomic literature regarding Trichuris from African native rodents describes 10 species, but includes few metric and morphologic characters that discriminate between some of the pairs. The whipworms we sampled in Tanzanian Natal multimammate mice and gerbils were morphologically identified, respectively, as Trichuris Mastomysi Verster, 1960 and Trichuris carlieri Gedoelst, 1916 sensu lato, but with characters that overlap or partially overlap with the cosmopolitan Murinae whipworm, Trichuris muris, already reported from several rodents in Africa. To clarify our identification, we sequenced the ITS-1, 5.8S, and ITS-2 ribosomal DNA region of the worms' nuclear genome. The genetic analyses clearly distinguish the...