Modulation of CD4(+) T Cell-Dependent Specific Cytotoxic CD8(+) T Cells Differentiation and Proliferation by the Timing of Increase in the Pathogen Load

Background. Following infection with viruses, bacteria or protozoan parasites, naive antigen-specific CD8(+) T cells undergo a process of differentiation and proliferation to generate effector cells. Recent evidences suggest that the timing of generation of specific effector CD8(+) T cells varies widely according to different pathogens. We hypothesized that the timing of increase in the pathogen load could be a critical parameter governing this process. Methodology/Principal Findings. Using increasing doses of the protozoan parasite Trypanosoma cruzi to infect C57BL/6 mice, we observed a significant acceleration in the timing of parasitemia without an increase in mouse susceptibility. in contrast, in CD8 deficient mice, we observed an inverse relationship between the parasite inoculum and the timing of death. These results suggest that in normal mice CD8(+) T cells became protective earlier, following the accelerated development of parasitemia. the evaluation of specific cytotoxic responses in vivo to three distinct epitopes revealed that increasing the parasite inoculum hastened the expansion of specific CD8(+) cytotoxic T cells following infection. the differentiation and expansion of T. cruzi-specific CD8(+) cytotoxic T cells is in fact dependent on parasite multiplication, as radiation-attenuated parasites were unable to activate these cells. We also observed that, in contrast to most pathogens, the activation process of T. cruzi-specific CD8(+) cytotoxic T cells was dependent on MHC class II restricted CD4(+) T cells. Conclusions/Significance. Our results are compatible with our initial hypothesis that the timing of increase in the pathogen load can be a critical parameter governing the kinetics of CD4(+) T cell-dependent expansion of pathogen-specific CD8(+) cytotoxic T cells.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Millennium Institute for Vaccine Development and TechnologyConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo, Escola Paulista Med, CINTERGEN, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilUniv Fed Rio de Janeiro, Inst Biofis Carlos Chagas Filho, Ilha Fundao, Ctr Ciencias Saude, BR-21941 Rio de Janeiro, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, CINTERGEN, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilMillennium Institute for Vaccine Development and Technology: CNPq - 420067/2005-1Web of Scienc

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

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

Immunity to Protozoan Parasites

Protozoan parasites cause several diseases, such as Malaria, Leishmaniasis, and Trypanosomiasis, hampering human development worldwide. Many protozoa cause infections that often follow chronic courses, owing to coevolution between parasites and host immune system. The survival and transmission of pathogenic protozoa depends on their ability to evade or subvert host’s innate and adaptive immune responses. A great challenge to research in immunology and parasitology is the development of strategies that favor immunity against protozoan parasites and prevent their evasion, chronic, or recurrent infections and associated pathologies. This special issue includes original papers and reviews that summarize current advances in our understanding on the mechanisms of immunity to protozoan parasites in humans and experimental animal models.Fil: Lopes, Marcela F. Universidade Federal do Rio de Janeiro; BrazilFil: Zamboni, Dario S. Faculdade de Medicina de Ribeirao Preto. Universidade de Sao Paulo; BrazilFil: Luján, Hugo Daniel. Universidad Católica de Córdoba. Facultad de Ciencias de la Salud; ArgentinaFil: Rodrigues, Mauricio M. , Escola Paulista de Medicina; Brazi

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

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

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