The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Scott E Lindner - One of the best experts on this subject based on the ideXlab platform.
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transcriptomics and proteomics reveal two waves of translational repression during the maturation of malaria parasite Sporozoites
Nature Communications, 2019Co-Authors: Scott E Lindner, Photini Sinnis, Kristian E Swearingen, Melanie J Shears, Michael P Walker, Erin N Vrana, Kevin J Hart, Allen M Minns, Robert L MoritzAbstract:Plasmodium Sporozoites are transmitted from infected mosquitoes to mammals, and must navigate the host skin and vasculature to infect the liver. This journey requires distinct proteomes. Here, we report the dynamic transcriptomes and proteomes of both oocyst Sporozoites and salivary gland Sporozoites in both rodent-infectious Plasmodium yoelii parasites and human-infectious Plasmodium falciparum parasites. The data robustly define mRNAs and proteins that are upregulated in oocyst Sporozoites (UOS) or upregulated in infectious Sporozoites (UIS) within the salivary glands, including many that are essential for sporozoite functions in the vector and host. Moreover, we find that malaria parasites use two overlapping, extensive, and independent programs of translational repression across sporozoite maturation to temporally regulate protein expression. Together with gene-specific validation experiments, these data indicate that two waves of translational repression are implemented and relieved at different times during sporozoite maturation, migration and infection, thus promoting their successful development and vector-to-host transition.
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extensive transcriptional and translational regulation occur during the maturation of malaria parasite Sporozoites
Unknown Journal, 2019Co-Authors: Scott E Lindner, Photini Sinnis, Kristian E Swearingen, Robert L Moritz, Melanie J Shears, Michael P Walker, Erin N Vrana, Kevin J Hart, Allen M Minns, Stefan H. I. KappeAbstract:Abstract Plasmodium Sporozoites are transmitted from an infected mosquito to mammals in which they infect the liver. The infectivity profile of Sporozoites changes as they egress from oocysts on the mosquito midgut into the hemocoel, and then invade the salivary glands, where they maintain a poised and infectious state until transmission occurs. Upon transmission, the sporozoite must then navigate the host skin, vasculature, and liver. All of these feats require distinct repertoires of proteins and capabilities that are coordinated in an appropriate temporal manner. Here, we report the comprehensive and dynamic transcriptomes and proteomes of both oocyst sporozoite and salivary gland sporozoite stages in both rodent-infectious Plasmodium yoelii parasites and human-infectious Plasmodium falciparum parasites. These data robustly define mRNAs and proteins that are Upregulated in Oocyst Sporozoites (UOS) or Upregulated in Infectious Sporozoites (UIS), which include critical gene products for sporozoite functions, as well as many of unknown importance that are similarly regulated. Moreover, we found that Plasmodium uses two overlapping, extensive, and independent programs of translational repression across sporozoite maturation to temporally regulate specific genes necessary to successfully navigate the mosquito vector and mammalian host environments. Finally, gene-specific validation experiments of selected, translationally repressed transcripts in P. yoelii confirmed the interpretations of the global transcriptomic and proteomic datasets. Together, these data indicate that two waves of translational repression are implemented and relieved at different times in sporozoite maturation to promote its successful life cycle progression.
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proteogenomic analysis of the total and surface exposed proteomes of plasmodium vivax salivary gland Sporozoites
PLOS Neglected Tropical Diseases, 2017Co-Authors: Scott E Lindner, Ashley M. Vaughan, Rapatbhorn Patrapuvich, Kristian E Swearingen, Erika L Flannery, Robert Morrison, Cristian Koepfli, Ivo MullerAbstract:Plasmodium falciparum and Plasmodium vivax cause the majority of human malaria cases. Research efforts predominantly focus on P. falciparum because of the clinical severity of infection and associated mortality rates. However, P. vivax malaria affects more people in a wider global range. Furthermore, unlike P. falciparum, P. vivax can persist in the liver as dormant hypnozoites that can be activated weeks to years after primary infection, causing relapse of symptomatic blood stages. This feature makes P. vivax unique and difficult to eliminate with the standard tools of vector control and treatment of symptomatic blood stage infection with antimalarial drugs. Infection by Plasmodium is initiated by the mosquito-transmitted sporozoite stage, a highly motile invasive cell that targets hepatocytes in the liver. The most advanced malaria vaccine for P. falciparum (RTS,S, a subunit vaccine containing of a portion of the major sporozoite surface protein) conferred limited protection in Phase III trials, falling short of WHO-established vaccine efficacy goals. However, blocking the sporozoite stage of infection in P. vivax, before the establishment of the chronic liver infection, might be an effective malaria vaccine strategy to reduce the occurrence of relapsing blood stages. It is also thought that a multivalent vaccine comprising multiple sporozoite surface antigens will provide better protection, but a comprehensive analysis of proteins in P. vivax Sporozoites is not available. To inform sporozoite-based vaccine development, we employed mass spectrometry-based proteomics to identify nearly 2,000 proteins present in P. vivax salivary gland Sporozoites. Analysis of protein post-translational modifications revealed extensive phosphorylation of glideosome proteins as well as regulators of transcription and translation. Additionally, the sporozoite surface proteins CSP and TRAP, which were recently discovered to be glycosylated in P. falciparum salivary gland Sporozoites, were also observed to be similarly modified in P. vivax Sporozoites. Quantitative comparison of the P. vivax and P. falciparum salivary gland sporozoite proteomes revealed a high degree of similarity in protein expression levels, including among invasion-related proteins. Nevertheless, orthologs with significantly different expression levels between the two species could be identified, as well as highly abundant, species-specific proteins with no known orthologs. Finally, we employed chemical labeling of live Sporozoites to isolate and identify 36 proteins that are putatively surface-exposed on P. vivax salivary gland Sporozoites. In addition to identifying conserved sporozoite surface proteins identified by similar analyses of other Plasmodium species, our analysis identified several as-yet uncharacterized proteins, including a putative 6-Cys protein with no known ortholog in P. falciparum.
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transcriptome and histone epigenome of plasmodium vivax salivary gland Sporozoites point to tight regulatory control and potential mechanisms for liver stage differentiation
bioRxiv, 2017Co-Authors: Rapatbhorn Patrapuvich, Jetsumon Sattabongkot, Sebastian A Mikolajczak, Ivo Muller, Aaron R Jex, Stefan I Kappe, Scott E LindnerAbstract:ABSTRACT Plasmodium vivax is the key obstacle to malaria elimination in Asia and Latin America, largely attributed to its ability to form resilient hypnozoites (sleeper-cells) in the host liver that escape treatment and cause relapsing infections. The decision to form hypnozoites is made early in the liver infection and may already be set in Sporozoites prior to invasion. To better understand these early stages of infection, we undertook a comprehensive transcriptomic and histone epigenetic characterization of P. vivax Sporozoites. The salivary-gland sporozoite transcriptome is heavily composed of transcripts associated with functions needed for early infection of the vertebrate host and development within hepatocytes. Through comparisons to recently published proteome data for the P. vivax sporozoite, our study finds that although highly transcribed, these transcripts are not detectable as proteins and may be regulated through translational repression; a finding we test for a small subset of transcripts and proteins through immunofluorescent microscopy of Sporozoites and liver stages in humanized mice. We identify differential transcription between the sporozoite and published transcriptomes of asexual blood-stages and mixed versus hypnozoite-enriched liver stages. These comparisons point to multiple layers of transcriptional, post-transcriptional and post-translational control that appear active in Sporozoites and to a lesser extent hypnozoites, but largely absent in replicating liver schizonts or mixed blood-stages. Common transcripts up-regulated in Sporozoites and hypnozoites compared to mixed (i.e., schizont) liver-stages identify genes linked to dormancy/persistence in bacteria, amoebae and plants. We also characterise histone epigenetic modifications in the P. vivax sporozoite and explore their role in regulating transcription. Collectively, these data support the hypothesis that the sporozoite as a tightly programmed stage primed to infect the human host and identifies potential mechanisms for hypnozoite-formation that may be further explored in liver stage models.
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ssp3 is a novel plasmodium yoelii sporozoite surface protein with a role in gliding motility
Infection and Immunity, 2014Co-Authors: Anke Harupa, Brandon K Sack, Viswanathan Lakshmanan, Nadia Arang, Alyse N Douglass, Brian G Oliver, Andrew B Stuart, Noah D Sather, Scott E Lindner, Kevin HybiskeAbstract:Plasmodium Sporozoites develop within oocysts in the mosquito midgut wall and then migrate to the salivary glands. After transmission, they embark on a complex journey to the mammalian liver, where they infect hepatocytes. Proteins on the sporozoite surface likely mediate multiple steps of this journey, yet only a few sporozoite surface proteins have been described. Here, we characterize a novel, conserved sporozoite surface protein (SSP3) in the rodent malaria parasite Plasmodium yoelii. SSP3 is a putative type I transmembrane protein unique to Plasmodium. By using epitope tagging and SSP3-specific antibodies in conjunction with immunofluorescence microscopy, we showed that SSP3 is expressed in mosquito midgut oocyst Sporozoites, exhibiting an intracellular localization. In Sporozoites derived from the mosquito salivary glands, however, SSP3 localized predominantly to the sporozoite surface as determined by immunoelectron microscopy. However, the ectodomain of SSP3 appeared to be inaccessible to antibodies in nonpermeabilized salivary gland Sporozoites. Antibody-induced shedding of the major surface protein circumsporozoite protein (CSP) exposed the SSP3 ectodomain to antibodies in some Sporozoites. Targeted deletion of SSP3 adversely affected in vitro sporozoite gliding motility, which, surprisingly, impacted neither their cell traversal capacity, host cell invasion in vitro, nor infectivity in vivo. Together, these data reveal a previously unappreciated complexity of the Plasmodium sporozoite surface proteome and the roles of surface proteins in distinct biological activities of Sporozoites.
Photini Sinnis - One of the best experts on this subject based on the ideXlab platform.
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transcriptomics and proteomics reveal two waves of translational repression during the maturation of malaria parasite Sporozoites
Nature Communications, 2019Co-Authors: Scott E Lindner, Photini Sinnis, Kristian E Swearingen, Melanie J Shears, Michael P Walker, Erin N Vrana, Kevin J Hart, Allen M Minns, Robert L MoritzAbstract:Plasmodium Sporozoites are transmitted from infected mosquitoes to mammals, and must navigate the host skin and vasculature to infect the liver. This journey requires distinct proteomes. Here, we report the dynamic transcriptomes and proteomes of both oocyst Sporozoites and salivary gland Sporozoites in both rodent-infectious Plasmodium yoelii parasites and human-infectious Plasmodium falciparum parasites. The data robustly define mRNAs and proteins that are upregulated in oocyst Sporozoites (UOS) or upregulated in infectious Sporozoites (UIS) within the salivary glands, including many that are essential for sporozoite functions in the vector and host. Moreover, we find that malaria parasites use two overlapping, extensive, and independent programs of translational repression across sporozoite maturation to temporally regulate protein expression. Together with gene-specific validation experiments, these data indicate that two waves of translational repression are implemented and relieved at different times during sporozoite maturation, migration and infection, thus promoting their successful development and vector-to-host transition.
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quantitative intravital imaging of plasmodium falciparum Sporozoites a novel platform to test malaria intervention strategies
Unknown Journal, 2019Co-Authors: Christine S Hopp, Sachie Kanatani, Nathan K Archer, Robert J Miller, Haiyun Liu, Kevin Chiou, Lloyd S Miller, Photini SinnisAbstract:Malaria infection starts with the injection of motile Plasmodium Sporozoites into the host9s skin during a mosquito bite. Previous studies using the rodent malaria model indicate that the dermal inoculation site may be where Sporozoites are most vulnerable to antibodies, yet, functional in vivo assays with human malaria parasites are lacking. Here, we present the first characterization of P. falciparum Sporozoites in the skin, comparing their motility to two rodent malaria species and investigating whether the environment of its natural host influences P. falciparum sporozoite motility using a human skin xenograft model. The combined data suggest that in contrast to the liver and blood stages, the skin is not a species-specific barrier for Plasmodium. We observe that P. falciparum Sporozoites inoculated into mouse skin move with similar speed, displacement and duration, and enter blood vessels in similar numbers as the rodent parasites. Thus, interventions targeting P. falciparum sporozoite migration can be tested in the murine dermis. Importantly, to streamline quantification of sporozoite motility, we developed a toolbox allowing for automated detection and tracking of Sporozoites in intravital microscopy videos. This establishes a platform to test vaccine candidates, immunization protocols, monoclonal antibodies and drug candidates for their impact on human malaria Sporozoites in vivo. Screening of intervention strategies for in vivo efficacy against Pf Sporozoites using this new platform will have the potential to validate targets prior to expensive clinical trials.
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extensive transcriptional and translational regulation occur during the maturation of malaria parasite Sporozoites
Unknown Journal, 2019Co-Authors: Scott E Lindner, Photini Sinnis, Kristian E Swearingen, Robert L Moritz, Melanie J Shears, Michael P Walker, Erin N Vrana, Kevin J Hart, Allen M Minns, Stefan H. I. KappeAbstract:Abstract Plasmodium Sporozoites are transmitted from an infected mosquito to mammals in which they infect the liver. The infectivity profile of Sporozoites changes as they egress from oocysts on the mosquito midgut into the hemocoel, and then invade the salivary glands, where they maintain a poised and infectious state until transmission occurs. Upon transmission, the sporozoite must then navigate the host skin, vasculature, and liver. All of these feats require distinct repertoires of proteins and capabilities that are coordinated in an appropriate temporal manner. Here, we report the comprehensive and dynamic transcriptomes and proteomes of both oocyst sporozoite and salivary gland sporozoite stages in both rodent-infectious Plasmodium yoelii parasites and human-infectious Plasmodium falciparum parasites. These data robustly define mRNAs and proteins that are Upregulated in Oocyst Sporozoites (UOS) or Upregulated in Infectious Sporozoites (UIS), which include critical gene products for sporozoite functions, as well as many of unknown importance that are similarly regulated. Moreover, we found that Plasmodium uses two overlapping, extensive, and independent programs of translational repression across sporozoite maturation to temporally regulate specific genes necessary to successfully navigate the mosquito vector and mammalian host environments. Finally, gene-specific validation experiments of selected, translationally repressed transcripts in P. yoelii confirmed the interpretations of the global transcriptomic and proteomic datasets. Together, these data indicate that two waves of translational repression are implemented and relieved at different times in sporozoite maturation to promote its successful life cycle progression.
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total and putative surface proteomics of malaria parasite salivary gland Sporozoites
Molecular & Cellular Proteomics, 2013Co-Authors: Scott E Lindner, Photini Sinnis, Anke Harupa, Ashley M. Vaughan, Stefan H. I. Kappe, Kristian E Swearingen, Robert L MoritzAbstract:Malaria infections of mammals are initiated by the transmission of Plasmodium salivary gland Sporozoites during an Anopheles mosquito vector bite. Sporozoites make their way through the skin and eventually to the liver, where they infect hepatocytes. Blocking this initial stage of infection is a promising malaria vaccine strategy. Therefore, comprehensively elucidating the protein composition of Sporozoites will be invaluable in identifying novel targets for blocking infection. Previous efforts to identify the proteins expressed in Plasmodium mosquito stages were hampered by the technical difficulty of separating the parasite from its vector; without effective purifications, the large majority of proteins identified were of vector origin. Here we describe the proteomic profiling of highly purified salivary gland Sporozoites from two Plasmodium species: human-infective Plasmodium falciparum and rodent-infective Plasmodium yoelii. The combination of improved sample purification and high mass accuracy mass spectrometry has facilitated the most complete proteome coverage to date for a pre-erythrocytic stage of the parasite. A total of 1991 P. falciparum sporozoite proteins and 1876 P. yoelii sporozoite proteins were identified, with >86% identified with high sequence coverage. The proteomic data were used to confirm the presence of components of three features critical for sporozoite infection of the mammalian host: the sporozoite motility and invasion apparatus (glideosome), sporozoite signaling pathways, and the contents of the apical secretory organelles. Furthermore, chemical labeling and identification of proteins on live Sporozoites revealed previously uncharacterized complexity of the putative sporozoite surface-exposed proteome. Taken together, the data constitute the most comprehensive analysis to date of the protein expression of salivary gland Sporozoites and reveal novel potential surface-exposed proteins that might be valuable targets for antibody blockage of infection.
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The skin: where malaria infection and the host immune response begin
Seminars in Immunopathology, 2012Co-Authors: Photini Sinnis, Fidel ZavalaAbstract:Infection by malaria parasites begins with the inoculation of Sporozoites into the skin of the host. The early events following sporozoite deposition in the dermis are critical for both the establishment of malaria infection and for the induction of protective immune responses. The initial sporozoite inoculum is generally low, and only a small percentage of these Sporozoites successfully reach the liver and grow to the next life cycle stage, making this a significant bottleneck for the parasite. Recent studies highlight the importance of sporozoite motility and host cell traversal in dermal exit. Importantly, protective immune responses against Sporozoites and liver stages of Plasmodium are induced by dendritic cells in the lymph node draining the skin inoculation site. The cellular, molecular, and immunological events that occur in the skin and associated lymph nodes are the topic of this review.
Kristian E Swearingen - One of the best experts on this subject based on the ideXlab platform.
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transcriptomics and proteomics reveal two waves of translational repression during the maturation of malaria parasite Sporozoites
Nature Communications, 2019Co-Authors: Scott E Lindner, Photini Sinnis, Kristian E Swearingen, Melanie J Shears, Michael P Walker, Erin N Vrana, Kevin J Hart, Allen M Minns, Robert L MoritzAbstract:Plasmodium Sporozoites are transmitted from infected mosquitoes to mammals, and must navigate the host skin and vasculature to infect the liver. This journey requires distinct proteomes. Here, we report the dynamic transcriptomes and proteomes of both oocyst Sporozoites and salivary gland Sporozoites in both rodent-infectious Plasmodium yoelii parasites and human-infectious Plasmodium falciparum parasites. The data robustly define mRNAs and proteins that are upregulated in oocyst Sporozoites (UOS) or upregulated in infectious Sporozoites (UIS) within the salivary glands, including many that are essential for sporozoite functions in the vector and host. Moreover, we find that malaria parasites use two overlapping, extensive, and independent programs of translational repression across sporozoite maturation to temporally regulate protein expression. Together with gene-specific validation experiments, these data indicate that two waves of translational repression are implemented and relieved at different times during sporozoite maturation, migration and infection, thus promoting their successful development and vector-to-host transition.
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extensive transcriptional and translational regulation occur during the maturation of malaria parasite Sporozoites
Unknown Journal, 2019Co-Authors: Scott E Lindner, Photini Sinnis, Kristian E Swearingen, Robert L Moritz, Melanie J Shears, Michael P Walker, Erin N Vrana, Kevin J Hart, Allen M Minns, Stefan H. I. KappeAbstract:Abstract Plasmodium Sporozoites are transmitted from an infected mosquito to mammals in which they infect the liver. The infectivity profile of Sporozoites changes as they egress from oocysts on the mosquito midgut into the hemocoel, and then invade the salivary glands, where they maintain a poised and infectious state until transmission occurs. Upon transmission, the sporozoite must then navigate the host skin, vasculature, and liver. All of these feats require distinct repertoires of proteins and capabilities that are coordinated in an appropriate temporal manner. Here, we report the comprehensive and dynamic transcriptomes and proteomes of both oocyst sporozoite and salivary gland sporozoite stages in both rodent-infectious Plasmodium yoelii parasites and human-infectious Plasmodium falciparum parasites. These data robustly define mRNAs and proteins that are Upregulated in Oocyst Sporozoites (UOS) or Upregulated in Infectious Sporozoites (UIS), which include critical gene products for sporozoite functions, as well as many of unknown importance that are similarly regulated. Moreover, we found that Plasmodium uses two overlapping, extensive, and independent programs of translational repression across sporozoite maturation to temporally regulate specific genes necessary to successfully navigate the mosquito vector and mammalian host environments. Finally, gene-specific validation experiments of selected, translationally repressed transcripts in P. yoelii confirmed the interpretations of the global transcriptomic and proteomic datasets. Together, these data indicate that two waves of translational repression are implemented and relieved at different times in sporozoite maturation to promote its successful life cycle progression.
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proteogenomic analysis of the total and surface exposed proteomes of plasmodium vivax salivary gland Sporozoites
PLOS Neglected Tropical Diseases, 2017Co-Authors: Scott E Lindner, Ashley M. Vaughan, Rapatbhorn Patrapuvich, Kristian E Swearingen, Erika L Flannery, Robert Morrison, Cristian Koepfli, Ivo MullerAbstract:Plasmodium falciparum and Plasmodium vivax cause the majority of human malaria cases. Research efforts predominantly focus on P. falciparum because of the clinical severity of infection and associated mortality rates. However, P. vivax malaria affects more people in a wider global range. Furthermore, unlike P. falciparum, P. vivax can persist in the liver as dormant hypnozoites that can be activated weeks to years after primary infection, causing relapse of symptomatic blood stages. This feature makes P. vivax unique and difficult to eliminate with the standard tools of vector control and treatment of symptomatic blood stage infection with antimalarial drugs. Infection by Plasmodium is initiated by the mosquito-transmitted sporozoite stage, a highly motile invasive cell that targets hepatocytes in the liver. The most advanced malaria vaccine for P. falciparum (RTS,S, a subunit vaccine containing of a portion of the major sporozoite surface protein) conferred limited protection in Phase III trials, falling short of WHO-established vaccine efficacy goals. However, blocking the sporozoite stage of infection in P. vivax, before the establishment of the chronic liver infection, might be an effective malaria vaccine strategy to reduce the occurrence of relapsing blood stages. It is also thought that a multivalent vaccine comprising multiple sporozoite surface antigens will provide better protection, but a comprehensive analysis of proteins in P. vivax Sporozoites is not available. To inform sporozoite-based vaccine development, we employed mass spectrometry-based proteomics to identify nearly 2,000 proteins present in P. vivax salivary gland Sporozoites. Analysis of protein post-translational modifications revealed extensive phosphorylation of glideosome proteins as well as regulators of transcription and translation. Additionally, the sporozoite surface proteins CSP and TRAP, which were recently discovered to be glycosylated in P. falciparum salivary gland Sporozoites, were also observed to be similarly modified in P. vivax Sporozoites. Quantitative comparison of the P. vivax and P. falciparum salivary gland sporozoite proteomes revealed a high degree of similarity in protein expression levels, including among invasion-related proteins. Nevertheless, orthologs with significantly different expression levels between the two species could be identified, as well as highly abundant, species-specific proteins with no known orthologs. Finally, we employed chemical labeling of live Sporozoites to isolate and identify 36 proteins that are putatively surface-exposed on P. vivax salivary gland Sporozoites. In addition to identifying conserved sporozoite surface proteins identified by similar analyses of other Plasmodium species, our analysis identified several as-yet uncharacterized proteins, including a putative 6-Cys protein with no known ortholog in P. falciparum.
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total and putative surface proteomics of malaria parasite salivary gland Sporozoites
Molecular & Cellular Proteomics, 2013Co-Authors: Scott E Lindner, Photini Sinnis, Anke Harupa, Ashley M. Vaughan, Stefan H. I. Kappe, Kristian E Swearingen, Robert L MoritzAbstract:Malaria infections of mammals are initiated by the transmission of Plasmodium salivary gland Sporozoites during an Anopheles mosquito vector bite. Sporozoites make their way through the skin and eventually to the liver, where they infect hepatocytes. Blocking this initial stage of infection is a promising malaria vaccine strategy. Therefore, comprehensively elucidating the protein composition of Sporozoites will be invaluable in identifying novel targets for blocking infection. Previous efforts to identify the proteins expressed in Plasmodium mosquito stages were hampered by the technical difficulty of separating the parasite from its vector; without effective purifications, the large majority of proteins identified were of vector origin. Here we describe the proteomic profiling of highly purified salivary gland Sporozoites from two Plasmodium species: human-infective Plasmodium falciparum and rodent-infective Plasmodium yoelii. The combination of improved sample purification and high mass accuracy mass spectrometry has facilitated the most complete proteome coverage to date for a pre-erythrocytic stage of the parasite. A total of 1991 P. falciparum sporozoite proteins and 1876 P. yoelii sporozoite proteins were identified, with >86% identified with high sequence coverage. The proteomic data were used to confirm the presence of components of three features critical for sporozoite infection of the mammalian host: the sporozoite motility and invasion apparatus (glideosome), sporozoite signaling pathways, and the contents of the apical secretory organelles. Furthermore, chemical labeling and identification of proteins on live Sporozoites revealed previously uncharacterized complexity of the putative sporozoite surface-exposed proteome. Taken together, the data constitute the most comprehensive analysis to date of the protein expression of salivary gland Sporozoites and reveal novel potential surface-exposed proteins that might be valuable targets for antibody blockage of infection.
John C. Beier - One of the best experts on this subject based on the ideXlab platform.
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Plasmodium yoelii sporozoite infectivity varies as a function of sporozoite loads in Anopheles stephensi mosquitoes.
The Journal of parasitology, 1997Co-Authors: Charles B. Pumpuni, Chandana Mendis, John C. BeierAbstract:Mechanisms by which Plasmodium Sporozoites survive and maintain their infectivity within the salivary glands of mosquitoes are unknown. In this study we establish a relationship between the number of Sporozoites present in the salivary glands of individual mosquitoes (sporozoite load) and sporozoite infectiousness (or "quality") as measured by infections in BALB/c or ICR mice. When Plasmodium yoelii-infected Anopheles stephensi mosquitoes were each allowed to feed on a single mouse, we noted that Sporozoites from mosquitoes with higher sporozoite loads were more infectious in 13 of 30 (43%) mice. In a second experiment, we inoculated mice with known numbers of Sporozoites from individual mosquitoes. Eleven of 18 (61%) and 16 of 18 (89%) mice that received 25 and 100 Sporozoites, respectively, became infected. For inoculations using 100 Sporozoites, again we noted that Sporozoites from mosquitoes with higher sporozoite loads were more infectious to mice. In a third and final experiment, the overall infectiousness of Sporozoites from individual mosquitoes was evaluated first by allowing individual mosquitoes to feed on individual mice and then by intravenous inoculations of 100 Sporozoites in a second mouse. There was a significant difference in host infections as a function of sporozoite loads in 14 of 19 (74%) mice. Analysis of the feeding times for infected versus noninfected mosquitoes did not show a significant difference between the 2 groups. The mean total feeding times for 50 infected and 45 noninfected An. stephensi mosquitoes were 306 (standard deviation [SD] = +/-230) and 441 (SD = +/-273) sec, respectively. Further, among infected An. stephensi mosquitoes there was no difference in probing times between cohorts that transmitted infectious Sporozoites to mice and cohorts that failed to transmit infectious Sporozoites. Our findings that sporozoite load influences sporozoite infectiousness or quality suggest that this may be an important factor in malaria parasite transmission.
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Sporozoite loads of naturally infected Anopheles in Kilifi District, Kenya.
Journal of the American Mosquito Control Association, 1997Co-Authors: Ephantus W. Kabiru, Charles M. Mbogo, Samuel K. Muiruri, John H. Ouma, J.i. Githure, John C. BeierAbstract:The number of salivary gland malaria Sporozoites (sporozoite load) was determined by hemacytometer counts for 2,055 field-collected Anopheles mosquitoes from Kilifi District, Kenya. Of 48 gland-positive Anopheles gambiae s.l., sporozoite loads ranged from 125 to 79,875, with a geometric mean of 1,743 Sporozoites per infected mosquito. About half of the infected mosquitoes had sporozoite loads < 1,000. Following hemacytometer examination of salivary gland samples, the same samples were subsequently tested for Plasmodium falciparum circumsporozoite (CS) protein by enzyme-linked immunosorbent assay (ELISA). The confirmation by ELISA of CS protein in 89.6% (43/48) of the salivary gland-positive samples compared to only 1.4% (28/2,007) of the dissection-negative mosquitoes indicated that dissection methods with hemacytometer counts of Sporozoites were adequate for detecting even low numbers of Sporozoites in field-collected mosquitoes. Detection of 17 or fewer Sporozoites in blood meals of 7 freshly bloodfed An. gambiae s.l. provides a further indication that the actual number of Sporozoites transmitted during bloodfeeding may be quite low.
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Noninfectious Sporozoites in the salivary glands of a minimally susceptible anopheline mosquito.
The Journal of parasitology, 1995Co-Authors: B H Noden, Jefferson A. Vaughan, Charles B. Pumpuni, John C. BeierAbstract:In studies to evaluate vector-malaria parasite relationships, we have found that Anopheles albimanus is minimally susceptible to the rodent malaria parasite Plasmodium yoelii. Normally, less than 10% of A. albimanus develop oocyst infections compared to 80-100% for Anopheles stephensi and Anopheles freeborni mosquitoes. Although Sporozoites produced in A. albimanus invade the salivary glands, they are not infectious to BALB/c or ICR mice. In 11 experiments with Sporozoites from A. albimanus, intravenous inoculations of up to 24,000 Sporozoites in individual mice failed to produce host infections. In contrast, inoculation of 300 Sporozoites obtained from the salivary glands of A. stephensi and A. freeborni always infected mice. The noninfectious Sporozoites from A. albimanus were morphologically similar to the infectious Sporozoites from A. stephensi and yielded 4+ circumsporozoite precipitin reactions when incubated with a monoclonal antibody against the circumsporozoite protein of P. yoelii. The presence of noninfectious Sporozoites in the salivary glands of A. albimanus suggests that this minimally susceptible vector either possesses a toxic factor that abolishes sporozoite infectiousness or lacks a critical substance needed by the sporozoite to become infectious. Sporozoite infectiousness was neither attenuated by incubation of infectious Sporozoites with A. albimanus salivary glands nor restored when noninfectious Sporozoites were incubated with A. stephensi salivary glands. These studies provide a starting point for defining the biological basis of sporozoite infectivity.
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effects of ingested human anti sporozoite sera on plasmodium falciparum sporogony in anopheles stephensi
American Journal of Tropical Medicine and Hygiene, 1993Co-Authors: Jonathan R. Davis, Charles B. Pumpuni, John C. Beier, Magda S. Beier, Robert R Edelman, D A Herrington, David F ClydeAbstract:Abstract We investigated the effects of human anti-sporozoite antibodies on the sporogonic development of Plasmodium falciparum in Anopheles stephensi. Equal volumes of washed human erythrocytes and human sera from 1) volunteers with protective immunity induced by immunization with irradiated P. falciparum Sporozoites, 2) the same volunteers before immunization, or 3) Kenyans exposed to natural sporozoite transmission, were fed to cohorts of P. falciparum-infected A. stephensi on either day 5, 8, or 11 after infection. A fourth group of infected mosquitoes from the same cohort were not refed. In two experiments, the effects of anti-sporozoite antibodies were evaluated by determining the infection rates and parasite densities for oocysts and salivary gland Sporozoites. There was no evidence that anti-sporozoite antibodies had any effect on the development or intensity of P. falciparum infection in A. stephensi. However, accelerated oocyst maturation was associated with mosquitoes taking a second blood meal, independent of serum source. Salivary gland Sporozoites from mosquitoes that fed on immune human sera contained bound human IgG, which was detectable by indirect immunofluorescence assay. The infectivity and transmission potential of human IgG-coated Sporozoites is unknown.
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Ingestion of Plasmodium Falciparum Sporozoites during Transmission by Anopheline Mosquitoes
The American journal of tropical medicine and hygiene, 1992Co-Authors: Magda S. Beier, Charles B. Pumpuni, Jonathan R. Davis, B H Noden, John C. BeierAbstract:We investigated the process of sporozoite transmission during blood feeding for Anopheles gambiae and An. stephensi experimentally infected with Plasmodium falciparum. When infective mosquitoes were fed 22-25 days postinfection on an anesthetized rat, Sporozoites were detected in the midgut of 96.5% of 57 An. gambiae (geometric mean [GM] = 32.5, range 3-374) and in 96.2% of 26 An. stephensi (GM = 19.5, range 1-345). There were no significant differences between species either in salivary gland sporozoite loads or in the number of ingested Sporozoites. There was a significant linear relationship between sporozoite loads and the numbers of ingested Sporozoites for both An. gambiae (r = 0.38) and An. stephensi (r = 0.69). Subsequently, An. gambiae were tested for sporozoite transmission by allowing them to feed individually on a suspended capillary tube containing 10 microliters of blood. A total of 83.3% of 18 infective mosquitoes transmitted a GM of 5.9 (range 1-36) Sporozoites. The same mosquitoes contained a GM of 23.4 (range 2-165) ingested Sporozoites. The number of ingested Sporozoites was related to sporozoite loads (r = 0.42) but not to the number of Sporozoites ejected into capillary tubes. Ingested Sporozoites remained in the midgut up to 10 hr after feeding. The comparable numbers of Sporozoites ingested by infective mosquitoes in both experiments indicates that the actual number of Sporozoites transmitted to the vertebrate host during blood feeding is significantly reduced by the blood ingestion process.(ABSTRACT TRUNCATED AT 250 WORDS)
Ivo Muller - One of the best experts on this subject based on the ideXlab platform.
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proteogenomic analysis of the total and surface exposed proteomes of plasmodium vivax salivary gland Sporozoites
PLOS Neglected Tropical Diseases, 2017Co-Authors: Scott E Lindner, Ashley M. Vaughan, Rapatbhorn Patrapuvich, Kristian E Swearingen, Erika L Flannery, Robert Morrison, Cristian Koepfli, Ivo MullerAbstract:Plasmodium falciparum and Plasmodium vivax cause the majority of human malaria cases. Research efforts predominantly focus on P. falciparum because of the clinical severity of infection and associated mortality rates. However, P. vivax malaria affects more people in a wider global range. Furthermore, unlike P. falciparum, P. vivax can persist in the liver as dormant hypnozoites that can be activated weeks to years after primary infection, causing relapse of symptomatic blood stages. This feature makes P. vivax unique and difficult to eliminate with the standard tools of vector control and treatment of symptomatic blood stage infection with antimalarial drugs. Infection by Plasmodium is initiated by the mosquito-transmitted sporozoite stage, a highly motile invasive cell that targets hepatocytes in the liver. The most advanced malaria vaccine for P. falciparum (RTS,S, a subunit vaccine containing of a portion of the major sporozoite surface protein) conferred limited protection in Phase III trials, falling short of WHO-established vaccine efficacy goals. However, blocking the sporozoite stage of infection in P. vivax, before the establishment of the chronic liver infection, might be an effective malaria vaccine strategy to reduce the occurrence of relapsing blood stages. It is also thought that a multivalent vaccine comprising multiple sporozoite surface antigens will provide better protection, but a comprehensive analysis of proteins in P. vivax Sporozoites is not available. To inform sporozoite-based vaccine development, we employed mass spectrometry-based proteomics to identify nearly 2,000 proteins present in P. vivax salivary gland Sporozoites. Analysis of protein post-translational modifications revealed extensive phosphorylation of glideosome proteins as well as regulators of transcription and translation. Additionally, the sporozoite surface proteins CSP and TRAP, which were recently discovered to be glycosylated in P. falciparum salivary gland Sporozoites, were also observed to be similarly modified in P. vivax Sporozoites. Quantitative comparison of the P. vivax and P. falciparum salivary gland sporozoite proteomes revealed a high degree of similarity in protein expression levels, including among invasion-related proteins. Nevertheless, orthologs with significantly different expression levels between the two species could be identified, as well as highly abundant, species-specific proteins with no known orthologs. Finally, we employed chemical labeling of live Sporozoites to isolate and identify 36 proteins that are putatively surface-exposed on P. vivax salivary gland Sporozoites. In addition to identifying conserved sporozoite surface proteins identified by similar analyses of other Plasmodium species, our analysis identified several as-yet uncharacterized proteins, including a putative 6-Cys protein with no known ortholog in P. falciparum.
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transcriptome and histone epigenome of plasmodium vivax salivary gland Sporozoites point to tight regulatory control and potential mechanisms for liver stage differentiation
bioRxiv, 2017Co-Authors: Rapatbhorn Patrapuvich, Jetsumon Sattabongkot, Sebastian A Mikolajczak, Ivo Muller, Aaron R Jex, Stefan I Kappe, Scott E LindnerAbstract:ABSTRACT Plasmodium vivax is the key obstacle to malaria elimination in Asia and Latin America, largely attributed to its ability to form resilient hypnozoites (sleeper-cells) in the host liver that escape treatment and cause relapsing infections. The decision to form hypnozoites is made early in the liver infection and may already be set in Sporozoites prior to invasion. To better understand these early stages of infection, we undertook a comprehensive transcriptomic and histone epigenetic characterization of P. vivax Sporozoites. The salivary-gland sporozoite transcriptome is heavily composed of transcripts associated with functions needed for early infection of the vertebrate host and development within hepatocytes. Through comparisons to recently published proteome data for the P. vivax sporozoite, our study finds that although highly transcribed, these transcripts are not detectable as proteins and may be regulated through translational repression; a finding we test for a small subset of transcripts and proteins through immunofluorescent microscopy of Sporozoites and liver stages in humanized mice. We identify differential transcription between the sporozoite and published transcriptomes of asexual blood-stages and mixed versus hypnozoite-enriched liver stages. These comparisons point to multiple layers of transcriptional, post-transcriptional and post-translational control that appear active in Sporozoites and to a lesser extent hypnozoites, but largely absent in replicating liver schizonts or mixed blood-stages. Common transcripts up-regulated in Sporozoites and hypnozoites compared to mixed (i.e., schizont) liver-stages identify genes linked to dormancy/persistence in bacteria, amoebae and plants. We also characterise histone epigenetic modifications in the P. vivax sporozoite and explore their role in regulating transcription. Collectively, these data support the hypothesis that the sporozoite as a tightly programmed stage primed to infect the human host and identifies potential mechanisms for hypnozoite-formation that may be further explored in liver stage models.
