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Vaccines against bovine babesiosis must, ideally, induce a humoral immune response characterized by neutralizing antibodies against conserved epitopes and a cellular Th1 immune response. In Babesia bovis , proteins such as AMA-1, MSA-2c, and RAP-1 have been characterized and antibodies against these proteins have shown a neutralizing effect, demonstrating the implication of B and T-cell epitopes in the immune response. There is evidence of the existence of B and T-cell epitopes in these proteins, however, it remains to be defined, the presence of conserved peptides in strains from around the world containing B and T-cell epitopes, and their role in the generation of a long-lasting immunity. The aim in this paper was to identify peptides of Babesia bovis AMA-1, MSA-2c, and RAP-1 that elicit a neutralizing and long-lasting Th1 immune response. Peptides containing B-cell epitopes of AMA-1, MSA-2c and RAP-1, were identified. The immune response generated by each peptide was characterized in cattle. All peptides tested induced antibodies that recognized intraerythrocytic parasites, however, only 5 peptides generated neutralizing antibodies in vitro : P2AMA-1 (6.28%), P3MSA-2c (10.27%), P4MSA-2c (10.42%), P1RAP-1 (32.45%), and P4RAP-1 (36.98%). When these neutralizing antibodies were evaluated as a pool, the inhibition percentage of invasion increased to 52.37%. When the T cellular response was evaluated, two peptides: P3MSA2c and P2AMA1 induced a higher percentage (>70%) of activated CD4 +/CD45RO+ T cells than unstimulated cells. Additionally, both peptides induced the production of gamma interferon (IFN−) in PBMCs from vaccinated cattle after one year proving the implication of a long-lasting Th1 immune response. In conclusion, we identified conserved peptides containing B and T-cell epitopes in antigens of B. bovis that elicit a Th1 immune response and showed evidence that peptides from the same protein elicit different immune responses, which has implication for vaccine development in bovine babesiosis. [ABSTRACT FROM AUTHOR]

Since inactivated influenza vaccines mainly confer protective immunity by inducing strain-specific antibodies to the viral hemagglutinin, these vaccines only afford protection against infection with antigenically matching influenza virus strains. Due to the continuous emergence of antigenic drift variants of seasonal influenza viruses and the inevitable future emergence of pandemic influenza viruses, there is considerable interest in the development of influenza vaccines that induce broader protective immunity. It has long been recognized that influenza virus-specific CD8 + T cells directed to epitopes located in the relatively conserved internal proteins can cross-react with various subtypes of influenza A virus. This implies that these CD8 + T cells, induced by prior influenza virus infections or vaccinations, could afford heterosubtypic immunity. Furthermore, influenza virus-specific CD4 + T cells have been shown to be important in protection from infection, either via direct cytotoxic effects or indirectly by providing help to B cells and CD8 + T cells. In the present paper, we review the induction of virus-specific T cell responses by influenza virus infection and the role of virus-specific CD4 + and CD8 + T cells in viral clearance and conferring protection from subsequent infections with homologous or heterologous influenza virus strains. Furthermore, we discuss vector-based vaccination strategies that aim at the induction of a cross-reactive virus-specific T cell response. [ABSTRACT FROM AUTHOR]

Abstract: Induction of CTL responses against protein antigens is an important aim in vaccine development. In this paper we present fusion-active virosomes as a vaccine delivery system capable of efficient induction of CTL responses in vivo. Virosomes are reconstituted viral membranes, which do not contain the genetic material of the virus they are derived from. Foreign macromolecules, including protein antigens, can be encapsulated in virosomes during the reconstitution process. Functionally reconstituted virosomes retain the cell binding and fusion characteristics of the native virus. Thus, upon uptake by cells through receptor-mediated endocytosis, virosomes will deliver their content to the cell cytosol. In a previous study, we demonstrated that protein antigens delivered in this manner to dendritic cells are efficiently processed for both MHC class I and class II presentation. Here, we studied in vivo induction of cellular immune responses against virosome-encapsulated ovalbumin (OVA) in mice. As little as 0.75μg OVA delivered by fusion-active virosomes was sufficient to induce a powerful class I MHC-restricted CTL response. All immunization routes that were used (i.m., i.p. and s.c.) resulted in efficient induction of CTL activity. The CTLs induced were cytotoxic in a standard 51Cr-release assay and produced IFNγ in response to OVA peptide. Thus, virosomes represent an ideal antigen delivery system for induction of cellular immunity against encapsulated protein antigens. [Copyright &y& Elsevier]