Highlights of the XXI annual meeting of the Brazilian Society of Protozoology, the XXXII annual meeting on Basic Research in Chagas' disease & an international symposium on vesicle trafficking in parasitic Protozoa – 7 to 9 November 2005, Caxambu, Minas Gerais, Brazil

This report focuses on the 2005 Annual meeting held in Caxambu, Minas Gerais, Brazil that was convened and organized by the Brazilian Society of Protozoology . This is an annual event and details of these meetings can be found on the Society's website. Within the space available it has been impossible to cover all the important and fascinating contributions and what is presented are our personal views of the meetings scientific highlights and new developments. The contents undoubtedly reflect each author's scientific interests and expertise. Fuller details of the round tables, seminars and posters can be consulted on line at

Serological detection of Plasmodium vivax malaria using recombinant proteins corresponding to the 19-kDa C-terminal region of the merozoite surface protein-1

Background: Serological tests to detect antibodies specific to Plasmodium vivax could be a valuable tool for epidemiological studies, for screening blood donors in areas where the malaria is not endemic and for diagnosis of infected individuals. Because P. vivax cannot be easily obtained in vitro, ELISA assays using total or semi-purified antigens are rarely used. Based on this limitation, we tested whether recombinant proteins representing the 19 kDa C-terminal region of the merozoite surface protein-1 of P. vivax (MSP1(19)) could be useful for serological detection of malaria infection.Methods: Three purified recombinant proteins produced in Escherichia coli (GST-MSP1(19), His(6)-MSP1(19) and His(6)-MSP1(19)-PADRE) and one in Pichia pastoris (yMSP1(19)-PADRE) were compared for their ability to bind to IgG antibodies of individuals with patent P. vivax infection. the method was tested with 200 serum samples collected from individuals living in the north of Brazil in areas endemic for malaria, 53 serum samples from individuals exposed to Plasmodium falciparum infection and 177 serum samples from individuals never exposed to malaria.Results: Overall, the sensitivity of the ELISA assessed with sera from naturally infected individuals was 95%. the proportion of serum samples that reacted with recombinant proteins GST-MSP1(19), His(6)-MSP1(19), His(6)-MSP1(19)-PADRE and yMSP1(19)-PADRE was 90%, 93.5%, 93.5% and 93.5%, respectively. the specificity values of the ELISA determined with sera from healthy individuals and from individuals with other infectious diseases were 98.3% (GST-MSP1(19)), 97.7% (His(6)-MSP1(19) and His(6)-MSP1(19)-PADRE) or 100% (yMSP1(19)-PADRE).Conclusions: Our study demonstrated that for the Brazilian population, an ELISA using a recombinant protein of the MSP1(19) can be used as the basis for the development of a valuable serological assay for the detection of P. vivax malaria.Univ São Paulo, Dept Anal Clin & Toxicol, Fac Ciencias Farmaceut, BR-05508900 São Paulo, BrazilFed Univ Para, Dept Patol, Ctr Ciencias Biol, BR-66075900 Belem, Para, BrazilMinist Salud, Inst Evandro Chagas, Secretaria Vigilancia Saude, BR-66090000 Belem, Para, BrazilHosp Israelita Albert Einstein, Dept Hemoterapia, BR-05651901 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, BrazilWeb of Scienc

Immunodominance: a new hypothesis to explain parasite escape and host/parasite equilibrium leading to the chronic phase of Chagas' disease?

Intense immune responses are observed during human or experimental infection with the digenetic protozoan parasite Trypanosoma cruzi. The reasons why such immune responses are unable to completely eliminate the parasites are unknown. The survival of the parasite leads to a parasite-host equilibrium found during the chronic phase of chagasic infection in most individuals. Parasite persistence is recognized as the most likely cause of the chagasic chronic pathologies. Therefore, a key question in Chagas' disease is to understand how this equilibrium is established and maintained for a long period. Understanding the basis for this equilibrium may lead to new approaches to interventions that could help millions of individuals at risk for infection or who are already infected with T. cruzi. Here, we propose that the phenomenon of immunodominance may be significant in terms of regulating the host-parasite equilibrium observed in Chagas' disease. T. cruzi infection restricts the repertoire of specific T cells generating, in some cases, an intense immunodominant phenotype and in others causing a dramatic interference in the response to distinct epitopes. This immune response is sufficiently strong to maintain the host alive during the acute phase carrying them to the chronic phase where transmission usually occurs. At the same time, immunodominance interferes with the development of a higher and broader immune response that could be able to completely eliminate the parasite. Based on this, we discuss how we can interfere with or take advantage of immunodominance in order to provide an immunotherapeutic alternative for chagasic individuals.Millennium Institute for Gene TherapyConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Centro Interdisciplinar de Terapia GênicaUNIFESP, EPM, Centro Interdisciplinar de Terapia GênicaFAPESP: 2006/1983-4||FAPESP: 2003/09675-9FAPESP: 2003/09672-0FAPESP: 2004/110106-6CNPq: 420067/2005-1CNPq: 307151/2006-9SciEL

A Plasmodium falciparum Strain Expressing GFP throughout the Parasite's Life-Cycle

The human malaria parasite Plasmodium falciparum is responsible for the majority of malaria-related deaths. Tools allowing the study of the basic biology of P. falciparum throughout the life cycle are critical to the development of new strategies to target the parasite within both human and mosquito hosts. We here present 3D7HT-GFP, a strain of P. falciparum constitutively expressing the Green Fluorescent Protein (GFP) throughout the life cycle, which has retained its capacity to complete sporogonic development. The GFP expressing cassette was inserted in the Pf47 locus. Using this transgenic strain, parasite tracking and population dynamics studies in mosquito stages and exo-erythrocytic schizogony is greatly facilitated. The development of 3D7HT-GFP will permit a deeper understanding of the biology of parasite-host vector interactions, and facilitate the development of high-throughput malaria transmission assays and thus aid development of new intervention strategies against both parasite and mosquito

Trans-sialidase delivered as a naked DNA vaccine elicits an immunological response similar to a Trypanosoma cruzi infection

Trypanosoma cruzi, the protozoan parasite that causes Chagas' disease, does not synthesize sialic acid, but expresses a trans-sialidase (TS) that catalyzes the transfer of sialic acid from host glycoconjugates to the parasite surface. Here, we review studies that characterize the immune response to the catalytic domain of the enzyme in humans during Chagas' disease or in mice following immunization with the TS gene. In both cases, there are antibodies that strongly inhibit the enzymatic activity and generation of interferon-g-producing T cells.Universidade Federal de São Paulo (UNIFESP)Instituto Dante Pazzanese de Cardiologia do Estado de São PauloUNIFESPSciEL

Towards the Immunoproteome of Neisseria meningitidis

Despite the introduction of conjugated polysaccharide vaccines for many of the Neisseria meningitidis serogroups, neisserial infections continue to cause septicaemia and meningitis across the world. This is in part due to the difficulties in developing a, cross-protective vaccine that is effective against all serogroups, including serogroup B meningococci. Although convalescent N. meningitidis patients develop a natural long-lasting cross-protective immunity, the antigens that mediate this response remain unknown. To help define the target of this protective immunity we identified the proteins recognized by IgG in sera from meningococcal patients by a combination of 2D protein gels, western blots and mass spectrometry. Although a number of outer membrane antigens were identified the majority of the antigens were cytoplasmic, with roles in cellular processes and metabolism. When recombinant proteins were expressed and used to raise sera in mice, none of the antigens elicited a positive SBA result, however flow cytometry did demonstrate that some, including the ribosomal protein, RplY were localised to the neisserial cell surface

Interaction of Cowpea Mosaic Virus (CPMV) Nanoparticles with Antigen Presenting Cells In Vitro and In Vivo

(CPMV) are increasingly being developed for applications in nanobiotechnology including vaccine development because of their potential for producing large quantities of antigenic material in plant hosts. In order to improve efficacy of viral nanoparticles in these types of roles, an investigation of the individual cell types that interact with the particles is critical. In particular, it is important to understand the interactions of a potential vaccine with antigen presenting cells (APCs) of the immune system. CPMV was previously shown to interact with vimentin displayed on cell surfaces to mediate cell entry, but the expression of surface vimentin on APCs has not been characterized. by flow cytometry and fluorescence confocal microscopy. The association of the particles with mouse gastrointestinal epithelium and Peyer's patches was also examined by confocal microscopy. The expression of surface vimentin on APCs was also measured., and that further tuning the interaction with surface vimentin may facilitate increased uptake by APCs and priming of antibody responses. These studies also indicate that CPMV particles likely access the systemic circulation following oral delivery via the Peyer's patch

A striking property of recombinant poxviruses: Efficient inducers of in vivo expansion of primed CD8(+) T cells

CSIC, Ctr Nacl Biotecnol, Madrid 28049, SpainNYU, Sch Med, Dept Med & Mol Parasitol, New York, NY 10010 USAEscola Paulista Med, BR-04023 São Paulo, BrazilEscola Paulista Med, BR-04023 São Paulo, BrazilWeb of Scienc

Virus-Like Particle Vaccine Protects against 2009 H1N1 Pandemic Influenza Virus in Mice

Background: The 2009 influenza pandemic and shortages in vaccine supplies worldwide underscore the need for new approaches to develop more effective vaccines. Methodology/Principal Findings: We generated influenza virus-like particles (VLPs) containing proteins derived from the A/ California/04/2009 virus, and tested their efficacy as a vaccine in mice. A single intramuscular vaccination with VLPs provided complete protection against lethal challenge with the A/California/04/2009 virus and partial protection against A/ PR/8/1934 virus, an antigenically distant human isolate. VLP vaccination induced predominant IgG2a antibody responses, high hemagglutination inhibition (HAI) titers, and recall IgG and IgA antibody responses. HAI titers after VLP vaccination were equivalent to those observed after live virus infection. VLP immune sera also showed HAI responses against diverse geographic pandemic isolates. Notably, a low dose of VLPs could provide protection against lethal infection. Conclusion/Significance: This study demonstrates that VLP vaccination provides highly effective protection against the 2009 pandemic influenza virus. The results indicate that VLPs can be developed into an effective vaccine, which can b

Potencial da técnica in vitro semi-automática de produção de gases para avaliação de silagens de sorgo (Sorghum bicolor (L.) Moench).

O potential da técnica in vitro semi-automática de produção de gases foi estudado pela avaliação das silagens de quatro híbridos de sorgo (BR700, BR701, BR601 e AG2002). Os resultados desse experimento foram comparados aos obtidos em experimento de digestibilidade aparente. A relação entre a digestibilidade da matéria seca obtida pela técnica de produção de gases após 96 horas de fermentação (DMS) e a digestibilidade aparente da MS foi representada pela equação: digestibilidade in vivo (g/kg) = 0,46 x DMS (g/kg) + 361 ,08 (r2=0,97). A técnica in vitro sem i automática de produção de gases estimou de forma precisa os valores de digestibilidade aparente da MS das silagens avaliadas nesse experimento. Além disto, forneceu informações adicionais sobre a cinética de fermentação ruminal das silagens e degradabilidade efetiva da matéria seca em diferentes taxas de passagem. A superioridade da taxa de produção de gases (%/h) do híbrido BR601 (0,056) em relação ao BR700 (0,051), BR701 (0,044) e AG2002 (0,045) está correlacionada com a maior DMS do material (649,598,601 e 593 g/kg, respectivamente). Dessa forma, a técnica in vitro semi-automática de produção de gases foi capaz de selecionar o híbrido BR60I, em termos de digestibilidade e cinética de fermentação ruminal, como o mais promissor para uso na alimentação dos ruminantes, demonstrando assim o seu potencial para avaliação de silagens de sorg