São Paulo School of Advanced Sciences on Vaccines: an overview

Two years ago, we held an exciting event entitled the São Paulo School of Advanced Sciences on Vaccines (SPSASV). Sixty-eight Ph.D. students, postdoctoral fellows and independent researchers from 37 different countries met at the Mendes Plaza Hotel located in the city of Santos, SP - Brazil to discuss the challenges and the new frontiers of vaccinology. The SPSASV provided a critical and comprehensive view of vaccine research from basics to the current state-of-the-art techniques performed worldwide. For 10 days, we discussed all the aspects of vaccine development in 36 lectures, 53 oral presentations and 2 poster sessions. At the end of the course, participants were further encouraged to present a model of a grant proposal related to vaccine development against individual pathogens. Among the targeted pathogens were viruses (Chikungunya, HIV, RSV, and Influenza), bacteria (Mycobacterium tuberculosis and Streptococcus pyogenes), parasites (Plasmodium falciparum or Plasmodium vivax), and the worm Strongyloides stercoralis. This report highlights some of the knowledge shared at the SPSASV.(AU)

TLR5-dependent immunogenicity of a recombinant fusion protein containing an immunodominant epitope of malarial circumsporozoite protein and the FliC flagellin of Salmonella Typhimurium

Recently, we described the improved immunogenicity of new malaria vaccine candidates based on the expression of fusion proteins containing immunodominant epitopes of merozoites and Salmonella enterica serovar Typhimurium flagellin (FliC) protein as an innate immune agonist. Here, we tested whether a similar strategy, based on an immunodominant B-cell epitope from malaria sporozoites, could also generate immunogenic fusion polypeptides. A recombinant His6-tagged FliC protein containing the C-terminal repeat regions of the VK210 variant of Plasmodium vivax circumsporozoite (CS) protein was constructed. This recombinant protein was successfully expressed in Escherichia coli as soluble protein and was purified by affinity to Ni-agarose beads followed by ion exchange chromatography. A monoclonal antibody specific for the CS protein of P. vivax sporozoites (VK210) was able to recognise the purified protein. C57BL/6 mice subcutaneously immunised with the recombinant fusion protein in the absence of any conventional adjuvant developed protein-specific systemic antibody responses. However, in mice genetically deficient in expression of TLR5, this immune response was extremely low. These results extend our previous observations concerning the immunogenicity of these recombinant fusion proteins and provide evidence that the main mechanism responsible for this immune activation involves interactions with TLR5, which has not previously been demonstrated for any recombinant FliC fusion protein.

Importance of CD8 T cell-mediated immune response during intracellular parasitic infections and its implications for the development of effective vaccines

Obligatory intracellular parasites such as Plasmodium sp, Trypanosoma cruzi, Toxoplasma gondii and Leishmania sp are responsible for the infection of hundreds of millions of individuals every year. These parasites can deliver antigens to the host cell cytoplasm that are presented through MHC class I molecules to protective CD8 T cells. The in vivo priming conditions of specific CD8 T cells during natural infection are largely unknown and remain as an area that has been poorly explored. The antiparasitic mechanisms mediated by CD8 T cells include both interferon-g-dependent and -independent pathways. The fact that CD8 T cells are potent inhibitors of parasitic development prompted many investigators to explore whether induction of these T cells can be a feasible strategy for the development of effective subunit vaccines against these parasitic diseases. Studies performed on experimental models supported the hypothesis that CD8 T cells induced by recombinant viral vectors or DNA vaccines could serve as the basis for human vaccination. Regimens of immunization consisting of two different vectors (heterologous prime-boost) are much more efficient in terms of expansion of protective CD8 T lymphocytes than immunization with a single vector. The results obtained using experimental models have led to clinical vaccination trials that are currently underway

Vacinação genética na infecção experimental pelo Trypanosoma cruzi utilizando genes expressos em diferentes estágios do desenvolvimento do parasita / Genetic vaccination during experimental infection with Trypanosoma cruzi using genes expressed in different developmental stages of the parasite

A imunização de I camundongos, com plasmídios contendo genes de Trypanosoma cruzi induziu anticorpos específicos, células T CD4+ Thl, CD8+ Tcl e imunidade protetora contra infecção. Até o momento em que iniciamos este trabalho os plasmídios utilizados para vacinação com DNA continham genes codificando antígenos expressos por tripomastigotas, as formas não replicativas do parasita. No presente estudo exploramos a possibilidade de utilizar genes expressos, por amastigotas, as formas do parasita que se replicam dentro das células do hospedeiro, para vacinação experimental com DNA. Com este fim, selecionamos para nosso estudo um gene relacionado à proteína-2 de superficie de amastigotas (ASP-2), um antígeno reconhecido por anticorpos e células T de camundongos e indivíduos infectados utilizando oligonucleotídeos específicos para o gene asp-2, quatro grupos distintos de genes foram amplificados a partir do cDNA de formas amastigotas da cepa Y de T. cruzi. Ao nível de nucleotídeos, eles compartilharam 82,3 a 89,9 por cento de identidade com o gene asp-2 descrito previamente. Um gene denominado clone 9 apresentou o maior grau de identidade com o gene asp-2 e foi selecionado para estudos imunológicos. Anti-soro policlonal gerado contra a porção C-terminal da proteína recombinante expressa pelo gene clone 9 reagiu comi um, antígeno i de aproximadamente 83 kDa expresso nas formas amastigotas de T cruzi. A imunização de camundongos BALB/c com plasmídios de expressão em células eucarióticas contendo o gene clone 9 induziu anticorpos específicos e a secreção de IFN- dependente de células T CD4+. Quando desafiados com formas tripomastigotas, os camundongos imunizados com os plasmídios contendo o gene clone 9 exibiram parasitemias reduzidas e sobreviveram à infecção letal, Subseqüentemente, testamos a hipótese de que talvez pudéssemos incrementar a, imunidade protetora contra a infecção experimental pela indução simultânea de uma resposta imune contra antígenos expressos nas formas amastigotas e tripomastigotas do T cruzi, Com este intuito, camundongos altamente suscetíveis A/Sn foram imunizados com plasmídios contendo o gene clone 9 ou o gene da trans-sialidase...