RESUMO
Because of the high variability of seasonal influenza viruses and the eminent threat of influenza viruses with pandemic potential, there is great interest in the development of vaccines that induce broadly protective immunity. Most probably, broadly protective influenza vaccines are based on conserved proteins, such as nucleoprotein (NP). NP is a vaccine target of interest as it has been shown to induce cross-reactive antibody and T cell responses. Here we tested and compared various NP-based vaccine preparations for their capacity to induce humoral and cellular immune responses to influenza virus NP. The immunogenicity of protein-based vaccine preparations with Matrix-M™ adjuvant as well as recombinant viral vaccine vector modified Vaccinia virus Ankara (MVA) expressing the influenza virus NP gene, with or without modifications that aim at optimization of CD8+ T cell responses, was addressed in BALB/c mice. Addition of Matrix-M™ adjuvant to NP wild-type protein-based vaccines significantly improved T cell responses. Furthermore, recombinant MVA expressing the influenza virus NP induced strong antibody and CD8+ T cell responses, which could not be improved further by modifications of NP to increase antigen processing and presentation.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Vacinas contra Influenza/imunologia , Influenza Humana/imunologia , Infecções por Orthomyxoviridae/imunologia , Orthomyxoviridae/imunologia , Proteínas de Ligação a RNA/metabolismo , Proteínas do Core Viral/metabolismo , Animais , Anticorpos Neutralizantes/metabolismo , Células Cultivadas , Reações Cruzadas , Feminino , Vetores Genéticos/genética , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Proteínas do Nucleocapsídeo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/imunologia , Vacinas de DNA , Vacinas de Subunidades Antigênicas , Vaccinia virus/genética , Proteínas do Core Viral/genética , Proteínas do Core Viral/imunologiaRESUMO
Cytotoxic cells of the immune system may kill infected or transformed host cells via the perforin/granzyme or the Fas ligand (FasL) pathways. The purpose of this study was to determine mRNA expression of perforin, granzyme A and FasL in Eimeria tenella-infected tissues at primary infection and infection of immune chickens as an indirect measure of cytotoxic cell activity. Chickens were rendered immune by repeated E. tenella infections, which were manifested as an absence of clinical signs or pathological lesions and significantly reduced oocyst production upon challenge infection. During primary E. tenella infection, perforin, granzyme A and FasL mRNA expression in caecal tissue was significantly increased at 10 days after infection, compared to uninfected birds. In contrast, at infection of immune birds, perforin and granzyme A mRNA expression in caecal tissue was significantly increased during the early stages of E. tenella challenge infection, days 1-4, which coincided with a substantial reduction of parasite replication in these birds. These results indicate the activation of cytotoxic pathways in immune birds and support a role for cytotoxic T cells in the protection against Eimeria infections.