Redefining the expressed prototype SICAvar gene involved in Plasmodium knowlesi antigenic variation

<p>Abstract</p> <p>Background</p> <p>The <it>SICAvar </it>gene family, expressed at the surface of infected erythrocytes, is critical for antigenic variation in <it>Plasmodium knowlesi</it>. When this family was discovered, a prototypic <it>SICAvar </it>gene was characterized and defined by a 10-exon structure. The predicted 205-kDa protein lacked a convincing signal peptide, but included a series of variable cysteine-rich modules, a transmembrane domain encoded by the penultimate exon, and a cytoplasmic domain encoded by the final highly conserved exon. The <it>205 SICAvar </it>gene and its family with up to 108 possible family members, was identified prior to the sequencing of the <it>P. knowlesi </it>genome. However, in the published <it>P. knowlesi </it>database this gene remains disjointed in five fragments. This study addresses a number of structural and functional questions that are critical for understanding <it>SICAvar </it>gene expression.</p> <p>Methods</p> <p>Database mining, bioinformatics, and traditional genomic and post-genomic experimental methods including proteomic technologies are used here to confirm the genomic context and expressed structure of the prototype <it>205 SICAvar </it>gene.</p> <p><b>Results</b></p> <p>This study reveals that the <it>205 SICAvar </it>gene reported previously to have a 10-exon expressed gene structure has, in fact, 12 exons, with an unusually large and repeat-laden intron separating two newly defined upstream exons and the <it>bona fide </it>5'UTR from the remainder of the gene sequence. The initial exon encodes a PEXEL motif, which may function to localize the SICA protein in the infected erythrocyte membrane. This newly defined start of the 205 <it>SICAvar </it>sequence is positioned on chromosome 5, over 340 kb upstream from the rest of the telomerically positioned <it>SICAvar </it>gene sequence in the published genome assembly. This study, however, verifies the continuity of these sequences, a 9.5 kb transcript, and provides evidence that the 205 <it>SICAvar </it>gene is located centrally on chromosome 5.</p> <p>Conclusion</p> <p>The prototype <it>205 SICAvar </it>gene has been redefined to have a 12-exon structure. These data are important because they 1) address questions raised in the <it>P. knowlesi </it>genome database regarding <it>SICAvar </it>gene fragments, numbers and structures, 2) show that this prototype gene encodes a PEXEL motif, 3) emphasize the need for further refinement of the <it>P. knowlesi </it>genome data, and 4) retrospectively, provide evidence for recombination within centrally located <it>SICAvar </it>sequences.</p

Comparison of the human immune responses to recombinant proteins representing three distinct surface proteins of Plasmodium vivax merozoites

Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM) Departamento de Microbiologia, Imunologia e ParasitologiaUniversidade Federal do Pará Departamento de PatologiaCenters for Disease Control and Prevention Division of Parasitic DiseasesInstituto Evandro ChagasUniversidade Federal de Minas Gerais Departamento de ParasitologiaUNIFESP, EPM, Depto. de Microbiologia, Imunologia e ParasitologiaSciEL

The relevance of non-human primate and rodent malaria models for humans

At the 2010 Keystone Symposium on "Malaria: new approaches to understanding Host-Parasite interactions", an extra scientific session to discuss animal models in malaria research was convened at the request of participants. This was prompted by the concern of investigators that skepticism in the malaria community about the use and relevance of animal models, particularly rodent models of severe malaria, has impacted on funding decisions and publication of research using animal models. Several speakers took the opportunity to demonstrate the similarities between findings in rodent models and human severe disease, as well as points of difference. The variety of malaria presentations in the different experimental models parallels the wide diversity of human malaria disease and, therefore, might be viewed as a strength. Many of the key features of human malaria can be replicated in a variety of nonhuman primate models, which are very under-utilized. The importance of animal models in the discovery of new anti-malarial drugs was emphasized. The major conclusions of the session were that experimental and human studies should be more closely linked so that they inform each other, and that there should be wider access to relevant clinical material

Antigenicity and Immunogenicity of Plasmodium vivax Merozoite Surface Protein-3

A recent clinical trial in African children demonstrated the potential utility of merozoite surface protein (MSP)-3 as a vaccine against Plasmodium falciparum malaria. the present study evaluated the use of Plasmodium vivax MSP-3 (PvMSP-3) as a target antigen in vaccine formulations against malaria caused by P. vivax. Recombinant proteins representing MSP-3 alpha and MSP-3 beta of P. vivax were expressed as soluble histidine-tagged bacterial fusions. Antigenicity during natural infection was evaluated by detecting specific antibodies using sera from individuals living in endemic areas of Brazil. A large proportion of infected individuals presented IgG antibodies to PvMSP-3 alpha (68.2%) and at least 1 recombinant protein representing PvMSP-3 beta (79.1%). in spite of the large responder frequency, reactivity to both antigens was significantly lower than was observed for the immunodominant epitope present on the 19-kDa C-terminal region of PvMSP-1. Immunogenicity of the recombinant proteins was studied in mice in the absence or presence of different adjuvant formulations. PvMSP-3 beta, but not PvMSP-3 alpha, induced a TLR4-independent humoral immune response in the absence of any adjuvant formulation. the immunogenicity of the recombinant antigens were also tested in formulations containing different adjuvants (Alum, Salmonella enterica flagellin, CpG, Quil A, TiterMax (R) and incomplete Freunds adjuvant) and combinations of two adjuvants (Alum plus flagellin, and CpG plus flagellin). Recombinant PvMSP-3 alpha and PvMSP-3 beta elicited higher antibody titers capable of recognizing P. vivax-infected erythrocytes harvested from malaria patients. Our results confirm that P. vivax MSP-3 antigens are immunogenic during natural infection, and the corresponding recombinant proteins may be useful in elucidating their vaccine potential.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)US National Institutes of Health, National Institute for Allergy and Infectious DiseasesSIgNHorizontal Programme on Infectious Diseases under the Agency for Science, Technology and Research (A*STAR, Singapore)Wellcome Trust of Great Britain, as part of the Oxford Tropical Medicine Research Programme of Wellcome Trust-Mahidol UniversityUniv São Paulo, Fac Ciencias Farmaceut, Dept Anal Clin & Toxicol, São Paulo, BrazilUniv Estadual Campinas, Dept Genet Evolucao & Bioagentes, Inst Biol, Campinas, SP, BrazilUniv São Paulo, Inst Ciencias Biomed, Dept Microbiol, BR-05508 São Paulo, BrazilNatl Univ Singapore, Yong Loo Lin Sch Med, Dept Microbiol, Singapore 117595, SingaporeAgcy Sci Technol & Res, Singapore Immunol Network, Biopolis, Singapore, SingaporeChurchill Hosp, Ctr Vaccinol & Trop Med, Oxford OX3 7LJ, EnglandMahidol Oxford Univ Trop Med Res Programme, Shoklo Malaria Res Unit, Mae Sot, ThailandEmory Univ, Emory Vaccine Ctr, Atlanta, GA 30322 USAEmory Univ, Yerkes Natl Primate Res Ctr, Atlanta, GA 30322 USAEmory Univ, Dept Med, Div Infect Dis, Atlanta, GA 30322 USACtr Dis Control & Prevent, Malaria Branch, Div Parasit Dis, Chamblee, GA USAUniversidade Federal de São Paulo, CTCMOL, Dept Microbiol Imunol & Parasitol, Escola Paulista Med, São Paulo, BrazilUniversidade Federal de São Paulo, CTCMOL, Dept Microbiol Imunol & Parasitol, Escola Paulista Med, São Paulo, BrazilFAPESP: 2010/09893-0US National Institutes of Health, National Institute for Allergy and Infectious Diseases: 1R01AI24710Web of Scienc

Crow Deaths Caused by West Nile Virus during Winter

In New York, an epizootic of American crow (Corvus brachyrhynchos) deaths from West Nile virus (WNV) infection occurred during winter 2004–2005, a cold season when mosquitoes are not active. Detection of WNV in feces collected at the roost suggests lateral transmission through contact or fecal contamination

Influence of HLA-DRB1 and HLA-DQB1 Alleles on IgG Antibody Response to the P. vivax MSP-1, MSP-3α and MSP-9 in Individuals from Brazilian Endemic Area

Background: the antibody response generated during malaria infections is of particular interest, since the production of specific IgG antibodies is required for acquisition of clinical immunity. However, variations in antibody responses could result from genetic polymorphism of the HLA class II genes. Given the increasing focus on the development of subunit vaccines, studies of the influence of class II alleles on the immune response in ethnically diverse populations is important, prior to the implementation of vaccine trials.Methods and Findings: in this study, we evaluated the influence of HLA-DRB1* and -DQB1* allelic groups on the naturally acquired humoral response from Brazilian Amazon individuals (n = 276) against P. vivax Merozoite Surface Protein-1 (MSP-1), MSP-3 alpha and MSP-9 recombinant proteins. Our results provide information concerning these three P. vivax antigens, relevant for their role as immunogenic surface proteins and vaccine candidates. Firstly, the studied population was heterogeneous presenting 13 HLA-DRB1* and 5 DQB1* allelic groups with a higher frequency of HLA-DRB1*04 and HLA-DQB1*03. the proteins studied were broadly immunogenic in a naturally exposed population with high frequency of IgG antibodies against PvMSP1-19 (86.7%), PvMSP-3 (77%) and PvMSP-9 (76%). Moreover, HLA-DRB1*04 and HLA-DQB1*03 alleles were associated with a higher frequency of IgG immune responses against five out of nine antigens tested, while HLA-DRB1* 01 was associated with a high frequency of non-responders to repetitive regions of PvMSP-9, and the DRB1*16 allelic group with the low frequency of responders to PvMSP3 full length recombinant protein.Conclusions: HLA-DRB1*04 alleles were associated with high frequency of antibody responses to five out of nine recombinant proteins tested in Rondonia State, Brazil. These features could increase the success rate of future clinical trials based on these vaccine candidates.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Yerkes National Primate Research Center BaseNational Center for Research Resources of the National Institutes of HealthNIHCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Inst Oswaldo Cruz, Lab Immunoparasitol, BR-20001 Rio de Janeiro, BrazilOswaldo Cruz Fdn Fiocruz, Ctr Technol Dev Hlth CDTS, Rio de Janeiro, BrazilInst Oswaldo Cruz, Lab Simulideos & Oncocercose, BR-20001 Rio de Janeiro, BrazilEmory Univ, Emory Vaccine Ctr, Atlanta, GA 30322 USAUniv Estado Rio de Janeiro, Histocompatibil & Cryopreservat Lab, Rio de Janeiro, BrazilUniversidade Federal de São Paulo, Ctr Terapia Celular & Mol CTCMol, Escola Paulista Med, São Paulo, BrazilEmory Univ, Sch Med, Div Infect Dis, Atlanta, GA USACDC Natl Ctr Infect Dis, Div Parasit Dis, Atlanta, GA USAUniversidade Federal de São Paulo, Ctr Terapia Celular & Mol CTCMol, Escola Paulista Med, São Paulo, BrazilFAPESP: 2009/15132-4Yerkes National Primate Research Center Base: RR00165NIH: RO1 AI0555994Web of Scienc

Transmedia, sofistas y el jogo bonito. Caso de estudio: Santander Fútbol Pasión

Artículo para la sección Tribuna de adComunica

No More Monkeying Around: Primate Malaria Model Systems are Key to Understanding Plasmodium vivax Liver-Stage Biology, Hypnozoites, and Relapses

Plasmodium vivax is a human malaria parasite responsible for significant morbidity worldwide and potentially death. This parasite possesses formidable liver-stage biology that involves the formation of dormant parasites known as hypnozoites. Hypnozoites are capable of activating weeks, months, or years after a primary blood-stage infection causing relapsing bouts of illness. Elimination of this dormant parasitic reservoir will be critical for global malaria eradication. Although hypnozoites were first discovered in 1982, few advancements have been made to understand their composition and biology. Until recently, in vitro models did not exist to study these forms and studying them from human ex vivo samples was virtually impossible. Today, non-human primate models and modern systems biology approaches are poised as tools to enable the in-depth study of P. vivax liver-stage biology, including hypnozoites and relapses. Non-human primate liver-stage model systems for P. vivax and the related simian malaria species P. cynomolgi are discussed along with perspectives regarding metabolite biomarker discovery, putative roles of extracellular vesicles, and relapse immunobiology