The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
Dominique Pontier - One of the best experts on this subject based on the ideXlab platform.
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Vaccination of free-living juvenile wild rabbits (Oryctolagus cuniculus) against Myxomatosis improved their survival.
Preventive Veterinary Medicine, 2007Co-Authors: Jean-sébastien Guitton, David Fouchet, Dominique Pontier, Sébastien Devillard, Michel Guénézan, Stéphane MarchandeauAbstract:Abstract For several decades, the populations of the European wild rabbit ( Oryctolagus cuniculus ) have declined, which is partly due to Myxomatosis. Vaccination against this disease is expected to contribute to restoration of rabbit populations but the actual impact of Myxomatosis is not well known and vaccination might have some negative effects. We analyzed the capture–mark–recapture data obtained in a 4-year field experiment (1991–1994) in a park near Paris, France wherein 300 out of 565 seronegative juvenile rabbits were vaccinated at first capture against Myxomatosis with the nontransmissible Dervaximyxo SG33© vaccine. After accounting for weight at first capture, age-class (juvenile/adult), “trap-happiness” and season (spring/autumn) of the capture event, vaccinated rabbits had 1.8-fold greater odds of surviving than the unvaccinated rabbits. The average summer survival risk for vaccinated juveniles was 0.63 (±0.08 S.E.) whereas it was 0.48 (±0.08 S.E.) for unvaccinated juvenile rabbits.
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Impact of Myxomatosis in relation to local persistence in wild rabbit populations: the role of waning immunity and the reproductive period.
Journal of theoretical biology, 2007Co-Authors: David Fouchet, Stéphane Marchandeau, Jean-sébastien Guitton, Dominique PontierAbstract:Many diseases are less severe when they are contracted in early life. For highly lethal diseases, such as Myxomatosis in rabbits, getting infected early in life can represent the best chance for an individual to survive the disease. For Myxomatosis, early infections are attenuated by maternal antibodies. This may lead to the immunisation of the host, preventing the subsequent development of the lethal form of the disease. But early infection of young individuals requires specific demographic and epidemiological contexts, such as a high transmission rate of the pathogen agent. To investigate other factors involved in the impact of such diseases, we have built a stochastic model of a rabbit metapopulation infected by Myxomatosis. We show that the impact of the pathogen agent can be reduced by early infections only when the agent has a long local persistence time and/or when the host subpopulations are highly connected. The length of the reproductive period and the duration of acquired immunity are also important factors influencing the persistence of the pathogen and thus, the impact of the disease. Besides confirming the role of classical factors in the persistence of a pathogen agent, such as the size of the subpopulation or the degree of connectivity, our results highlight novel factors that can modulate the impact of diseases whose severity increase with age.
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Waning of maternal immunity and the impact of diseases: the example of Myxomatosis in natural rabbit populations.
Journal of Theoretical Biology, 2006Co-Authors: David Fouchet, Stéphane Marchandeau, Michel Langlais, Dominique PontierAbstract:Myxomatosis is a leporipoxvirus that infects the european rabbit, inducing a high mortality rate. Observations lead us to hypothesize that a rabbit carrying maternal antibodies (or having recovered) can be infected (or re-infected) upon being exposed (or re-exposed) to the virus. Infection will lead to mild disease, boosting host immune protection. Using a modelling approach we show that this phenomenon may lead to a difference of impact of Myxomatosis according to its transmission rate. Young are exposed when they still carry maternal antibodies and develop a mild disease in high transmission populations. Our results show that the impact of Myxomatosis is generally higher in epidemic situations compared to populations where the virus circulates all the year. As a consequence, waning of acquired immunity and the continuous supply of newborn along the year may reduce the impact of the disease.
Rafael Villafuerte - One of the best experts on this subject based on the ideXlab platform.
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large scale assessment of Myxomatosis prevalence in european wild rabbits oryctolagus cuniculus 60 years after first outbreak in spain
Research in Veterinary Science, 2017Co-Authors: Rafael Villafuerte, Francisca Castro, Esther Ramirez, Irene Cotilla, Francisco Parra, Miguel Delibesmateos, Pilar Recuerda, Carlos RoucoAbstract:Myxomatosis is a viral disease that affects European rabbits (Oryctolagus cuniculus) worldwide. In Spain, populations of wild rabbits drastically decreased in the 1950s after the first outbreak of Myxomatosis. Since that first appearance, it seems to be an annual epizootic in Spain with periodic outbreaks, predominantly in summer and autumn. Taking into account rabbit population structure, abundance, and genetic lineage, this paper attempts to make a large-scale characterization of Myxomatosis seroprevalence based on the immune status of 29 rabbit populations distributed throughout Spain, where O. cuniculus cuniculus and O. c. algirus, the two known rabbit subspecies, naturally inhabit. A total of 654 samples were collected between 2003 and 2009, and seroprevalence of antibodies against Myxoma virus (MYXV) was determined. Overall, our results revealed that 53% of the rabbit samples were positive to antibodies against MYXV. Newborn and juvenile rabbits were the most susceptible animals to the virus, with 19% and 16% seropositivity for newborn and juveniles, respectively, while adult rabbits were the most protected, with 65% of seropositive samples. This suggests that prevalence is negatively related to the proportion of newborn and juvenile rabbits in a population. Our results also showed that seroprevalence against MYXV tended to be higher in high-abundance populations. In contrast, no differences were detected in seroprevalence between rabbit subspecies. This study confirms that >60years since first outbreak, Myxomatosis is an endemic disease in Spain. Based on the results, the establishment of a Myxomatosis surveillance protocol is proposed.
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Field experimental vaccination campaigns against Myxomatosis and their effectiveness in the wild.
Vaccine, 2009Co-Authors: Catarina Ferreira, Francisca Castro, Esther Ramirez, Pablo Ferreras, Paulo C. Alves, Steve Redpath, Rafael VillafuerteAbstract:We conducted a field experiment in SW Spain to test the efficacy of a Myxomatosis vaccine, a viral disease strongly affecting wild rabbit populations, by assessing individual survival and antibody seroprevalence of monthly live-trapped, vaccinated (N=466) and unvaccinated (N=558) juvenile wild rabbits, between April and October 2007. Eight percent of all juveniles caught from April to June showed maternal antibodies against Myxomatosis, whereas all animals were seropositive to the disease after the outbreak. Juveniles vaccinated before the outbreak showed 17% higher survival (31% vs. 14%) and an increased mortality probability of 8% after the outbreak. Results suggest that only a costly and systematic vaccination performed before the annual Myxomatosis outbreak, would improve the survival of juvenile rabbits, a premise not always accomplished that compromises its efficacy in the field.
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epidemiology of viral haemorrhagic disease and Myxomatosis in a free living population of wild rabbits
Veterinary Record, 2002Co-Authors: C Calvete, Rafael Villafuerte, R Estrada, J J Osacar, J LucientesAbstract:From January 1993 to June 1996, the epidemiology of Myxomatosis and viral haemorrhagic disease (VHD) was studied in a free-living population of wild rabbits ( Oryctolagus cuniculus ) in Spain by means of serological surveys and radiotracking. Myxomatosis was endemic and associated with the breeding period. Its serological pattern was characterised by a 100 per cent prevalence of antibodies in adult rabbits and a rapid increase in antibodies in young rabbits in their first year. No mortality from Myxomatosis was detected in adults, and mortality in young rabbits could not be estimated because of interference by predators and scavengers and the deaths of many radiotagged rabbits inside their burrows. VHD was also an endemic disease associated with the breeding period. Adults had a higher prevalence of antibodies against VHD than young rabbits, teaching values of 80 to 90 per cent. During the study, there was an increase in rabbit numbers as a result of a decrease in mortality from predation which was associated with an increase in mortality due to VHD and in the prevalence of antibodies to VHD. Mortality from VHD was lower in rabbits with VHD antibodies than in seronegative rabbits, but some mortality from the disease was also detected in seropositive rabbits. The annual mean mortality rate due to VHD in adult rabbits was estimated to be 21.8 per cent
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Size of Rabbits consumed by Black Kites increased after a Rabbit epizootic
Mammal Review, 1999Co-Authors: Rafael Villafuerte, Javier ViñuelaAbstract:Rabbits are the staple prey for Black Kites in Matasgordas, south-western Spain. Because of their poor predatory skills, it has been considered that most of the Rabbits consumed by Kites were young and affected by Myxomatosis. After rabbit haemorrhagic disease (RHD) arrived in Spain, and since most of the Rabbits affected were adults, it was expected that the raptor would benefit with the incorporation of larger Rabbits in its diet. In concordance with that prediction, during the immediate three years before the arrival of RHD (1987–89), average size of Rabbits consumed by nestling Black Kites were similar and corresponded to the size of those Rabbits affected by Myxomatosis. However, after RHD arrival in 1990, sizes of Rabbits consumed by Kites increased, corresponding to the age more frequently affected by RHD.
Stéphane Marchandeau - One of the best experts on this subject based on the ideXlab platform.
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Vaccination of free-living juvenile wild rabbits (Oryctolagus cuniculus) against Myxomatosis improved their survival.
Preventive Veterinary Medicine, 2007Co-Authors: Jean-sébastien Guitton, David Fouchet, Dominique Pontier, Sébastien Devillard, Michel Guénézan, Stéphane MarchandeauAbstract:Abstract For several decades, the populations of the European wild rabbit ( Oryctolagus cuniculus ) have declined, which is partly due to Myxomatosis. Vaccination against this disease is expected to contribute to restoration of rabbit populations but the actual impact of Myxomatosis is not well known and vaccination might have some negative effects. We analyzed the capture–mark–recapture data obtained in a 4-year field experiment (1991–1994) in a park near Paris, France wherein 300 out of 565 seronegative juvenile rabbits were vaccinated at first capture against Myxomatosis with the nontransmissible Dervaximyxo SG33© vaccine. After accounting for weight at first capture, age-class (juvenile/adult), “trap-happiness” and season (spring/autumn) of the capture event, vaccinated rabbits had 1.8-fold greater odds of surviving than the unvaccinated rabbits. The average summer survival risk for vaccinated juveniles was 0.63 (±0.08 S.E.) whereas it was 0.48 (±0.08 S.E.) for unvaccinated juvenile rabbits.
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Impact of Myxomatosis in relation to local persistence in wild rabbit populations: the role of waning immunity and the reproductive period.
Journal of theoretical biology, 2007Co-Authors: David Fouchet, Stéphane Marchandeau, Jean-sébastien Guitton, Dominique PontierAbstract:Many diseases are less severe when they are contracted in early life. For highly lethal diseases, such as Myxomatosis in rabbits, getting infected early in life can represent the best chance for an individual to survive the disease. For Myxomatosis, early infections are attenuated by maternal antibodies. This may lead to the immunisation of the host, preventing the subsequent development of the lethal form of the disease. But early infection of young individuals requires specific demographic and epidemiological contexts, such as a high transmission rate of the pathogen agent. To investigate other factors involved in the impact of such diseases, we have built a stochastic model of a rabbit metapopulation infected by Myxomatosis. We show that the impact of the pathogen agent can be reduced by early infections only when the agent has a long local persistence time and/or when the host subpopulations are highly connected. The length of the reproductive period and the duration of acquired immunity are also important factors influencing the persistence of the pathogen and thus, the impact of the disease. Besides confirming the role of classical factors in the persistence of a pathogen agent, such as the size of the subpopulation or the degree of connectivity, our results highlight novel factors that can modulate the impact of diseases whose severity increase with age.
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Waning of maternal immunity and the impact of diseases: the example of Myxomatosis in natural rabbit populations.
Journal of Theoretical Biology, 2006Co-Authors: David Fouchet, Stéphane Marchandeau, Michel Langlais, Dominique PontierAbstract:Myxomatosis is a leporipoxvirus that infects the european rabbit, inducing a high mortality rate. Observations lead us to hypothesize that a rabbit carrying maternal antibodies (or having recovered) can be infected (or re-infected) upon being exposed (or re-exposed) to the virus. Infection will lead to mild disease, boosting host immune protection. Using a modelling approach we show that this phenomenon may lead to a difference of impact of Myxomatosis according to its transmission rate. Young are exposed when they still carry maternal antibodies and develop a mild disease in high transmission populations. Our results show that the impact of Myxomatosis is generally higher in epidemic situations compared to populations where the virus circulates all the year. As a consequence, waning of acquired immunity and the continuous supply of newborn along the year may reduce the impact of the disease.
David Fouchet - One of the best experts on this subject based on the ideXlab platform.
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Vaccination of free-living juvenile wild rabbits (Oryctolagus cuniculus) against Myxomatosis improved their survival.
Preventive Veterinary Medicine, 2007Co-Authors: Jean-sébastien Guitton, David Fouchet, Dominique Pontier, Sébastien Devillard, Michel Guénézan, Stéphane MarchandeauAbstract:Abstract For several decades, the populations of the European wild rabbit ( Oryctolagus cuniculus ) have declined, which is partly due to Myxomatosis. Vaccination against this disease is expected to contribute to restoration of rabbit populations but the actual impact of Myxomatosis is not well known and vaccination might have some negative effects. We analyzed the capture–mark–recapture data obtained in a 4-year field experiment (1991–1994) in a park near Paris, France wherein 300 out of 565 seronegative juvenile rabbits were vaccinated at first capture against Myxomatosis with the nontransmissible Dervaximyxo SG33© vaccine. After accounting for weight at first capture, age-class (juvenile/adult), “trap-happiness” and season (spring/autumn) of the capture event, vaccinated rabbits had 1.8-fold greater odds of surviving than the unvaccinated rabbits. The average summer survival risk for vaccinated juveniles was 0.63 (±0.08 S.E.) whereas it was 0.48 (±0.08 S.E.) for unvaccinated juvenile rabbits.
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Impact of Myxomatosis in relation to local persistence in wild rabbit populations: the role of waning immunity and the reproductive period.
Journal of theoretical biology, 2007Co-Authors: David Fouchet, Stéphane Marchandeau, Jean-sébastien Guitton, Dominique PontierAbstract:Many diseases are less severe when they are contracted in early life. For highly lethal diseases, such as Myxomatosis in rabbits, getting infected early in life can represent the best chance for an individual to survive the disease. For Myxomatosis, early infections are attenuated by maternal antibodies. This may lead to the immunisation of the host, preventing the subsequent development of the lethal form of the disease. But early infection of young individuals requires specific demographic and epidemiological contexts, such as a high transmission rate of the pathogen agent. To investigate other factors involved in the impact of such diseases, we have built a stochastic model of a rabbit metapopulation infected by Myxomatosis. We show that the impact of the pathogen agent can be reduced by early infections only when the agent has a long local persistence time and/or when the host subpopulations are highly connected. The length of the reproductive period and the duration of acquired immunity are also important factors influencing the persistence of the pathogen and thus, the impact of the disease. Besides confirming the role of classical factors in the persistence of a pathogen agent, such as the size of the subpopulation or the degree of connectivity, our results highlight novel factors that can modulate the impact of diseases whose severity increase with age.
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Waning of maternal immunity and the impact of diseases: the example of Myxomatosis in natural rabbit populations.
Journal of Theoretical Biology, 2006Co-Authors: David Fouchet, Stéphane Marchandeau, Michel Langlais, Dominique PontierAbstract:Myxomatosis is a leporipoxvirus that infects the european rabbit, inducing a high mortality rate. Observations lead us to hypothesize that a rabbit carrying maternal antibodies (or having recovered) can be infected (or re-infected) upon being exposed (or re-exposed) to the virus. Infection will lead to mild disease, boosting host immune protection. Using a modelling approach we show that this phenomenon may lead to a difference of impact of Myxomatosis according to its transmission rate. Young are exposed when they still carry maternal antibodies and develop a mild disease in high transmission populations. Our results show that the impact of Myxomatosis is generally higher in epidemic situations compared to populations where the virus circulates all the year. As a consequence, waning of acquired immunity and the continuous supply of newborn along the year may reduce the impact of the disease.
Peter J. Kerr - One of the best experts on this subject based on the ideXlab platform.
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Myxomatosis in Australia and Europe: a model for emerging infectious diseases.
Antiviral research, 2012Co-Authors: Peter J. KerrAbstract:Myxoma virus is a poxvirus naturally found in two American leporid (rabbit) species (Sylvilagus brasiliensis and Sylvilagus bachmani) in which it causes an innocuous localised cutaneous fibroma. However, in European rabbits (Oryctolagus cuniculus) the same virus causes the lethal disseminated disease Myxomatosis. The introduction of myxoma virus into the European rabbit population in Australia in 1950 initiated the best known example of what happens when a novel pathogen jumps into a completely naive new mammalian host species. The short generation time of the rabbit and their vast numbers in Australia meant evolution could be studied in real time. The carefully documented emergence of attenuated strains of virus that were more effectively transmitted by the mosquito vector and the subsequent selection of rabbits with genetic resistance to Myxomatosis is the paradigm for pathogen virulence and host-pathogen coevolution. This natural experiment was repeated with the release of a separate strain of myxoma virus in France in 1952. The subsequent spread of the virus throughout Europe and its coevolution with the rabbit essentially paralleled what occurred in Australia. Detailed molecular studies on myxoma virus have dissected the role of virulence genes in the pathogenesis of Myxomatosis and when combined with genomic data and reverse genetics should in future enable the understanding of the molecular evolution of the virus as it adapted to its new host. This review describes the natural history and evolution of myxoma virus together with the molecular biology and experimental pathogenesis studies that are informing our understanding of evolution of emerging diseases.
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Limitations of plasmid vaccines to complex viruses: selected myxoma virus antigens as DNA vaccines were not protective
Vaccine, 2004Co-Authors: Mathew M. Adams, B. Van Leeuwen, Peter J. KerrAbstract:Myxoma virus, a poxvirus of the genus Leporipoxvirus, is the causative agent of the disease Myxomatosis which is highly lethal in European rabbits (Oryctolagus cuniculus). Current vaccines to protect against Myxomatosis are either attenuated live strains of the virus or the antigenically related rabbit fibroma virus. We examined the immune response of outbred domestic rabbits to the individual myxoma virus antigens M055R, M073R, M115L and M121R, delivered as DNA vaccines co-expressing rabbit interleukin-2 or interleukin-4. M115L and M121R were also delivered simultaneously. None of the vaccine constructs were able to protect the rabbits from disease or reduce mortality after challenge with virulent myxoma virus, despite induction of antigen-specific cell-mediated and humoral immune responses.
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Expression of rabbit IL-4 by recombinant myxoma viruses enhances virulence and overcomes genetic resistance to Myxomatosis
Virology, 2004Co-Authors: Peter J. Kerr, Harvey D. Perkins, B. Inglis, R. Stagg, Eileen A. Mclaughlin, S.v Collins, B. H. Van LeeuwenAbstract:Rabbit IL-4 was expressed in the virulent standard laboratory strain (SLS) and the attenuated Uriarra (Ur) strain of myxoma virus with the aim of creating a Th2 cytokine environment and inhibiting the development of an antiviral cell-mediated response to Myxomatosis in infected rabbits. This allowed testing of a model for genetic resistance to Myxomatosis in wild rabbits that have undergone 50 years of natural selection for resistance to Myxomatosis. Expression of IL-4 significantly enhanced virulence of both virulent and attenuated virus strains in susceptible (laboratory) and resistant (wild) rabbits. SLS-IL-4 completely overcame genetic resistance in wild rabbits. The pathogenesis of SLS-IL-4 was compared in susceptible and resistant rabbits. The results support a model for resistance to Myxomatosis of an enhanced innate immune response controlling virus replication and allowing an effective antiviral cell-mediated immune response to develop in resistant rabbits. Expression of IL-4 did not overcome immunity to Myxomatosis induced by immunization.
