RESUMO
Infections with influenza and respiratory syncytial virus (RSV) rank high among the most common human respiratory diseases worldwide. Previously, we developed a replication-incompetent influenza virus by replacing the coding sequence of the PB2 gene, which encodes one of the viral RNA polymerase subunits, with that of a reporter gene. Here, we generated a PB2-knockout recombinant influenza virus expressing the F protein of RSV (PB2-RSVF virus) and tested its potential as a bivalent vaccine. In mice intranasally immunized with the PB2-RSVF virus, we detected high levels of antibodies against influenza virus, but not RSV. PB2-RSVF virus-immunized mice were protected from a lethal challenge with influenza virus but experienced severe body weight loss when challenged with RSV, indicating that PB2-RSVF vaccination enhanced RSV-associated disease. These results highlight one of the difficulties of developing an effective bivalent vaccine against influenza virus and RSV infections.
Assuntos
Vacinas contra Influenza/imunologia , Infecções por Orthomyxoviridae/prevenção & controle , Vírus Sinciciais Respiratórios/imunologia , Proteínas Virais de Fusão/metabolismo , Animais , Feminino , Regulação Viral da Expressão Gênica , Células HEK293 , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Infecções por Vírus Respiratório Sincicial/prevenção & controle , Vírus Sinciciais Respiratórios/metabolismo , Vacinas Sintéticas/imunologia , Replicação ViralRESUMO
DNA vaccines are promising tools to fight parasitic diseases, including amoebiasis caused by the protozoan Entamoeba histolytica. Here we studied the immunogenicity and protective efficacy of a DNA vaccine against this parasite composed by the EhCPADH surface complex encoding genes (Ehcp112 and Ehadh112). EhCPADH is formed by an adhesin (EhADH112) and a cysteine proteinase (EhCP112), both involved in the parasite virulence. We evaluated transcription, protein expression, immunological response and protection against hepatic amoebiasis in hamsters intradermally and intramuscularly immunized with a mixture of pcDNA-Ehadh112 and pcDNA-Ehcp112 plasmids. RT-PCR and immunohistochemical assays showed that both antigens were differentially expressed in spleen and liver of immunized animals. No significant antibody immune response was induced by either route. However, intradermally inoculated hamsters presented a robust Th1-like immune response, characterized by high levels of INF-gamma and TNF-alpha cytokines, detected in the liver of animals challenged with virulent trophozoites. Animals showed significant protection against amoebiasis manifested by a higher survival rate and a significant prevention of liver abscess formation. We conclude that a refinement of this DNA vaccine could be a good choice to control hepatic amoebiasis.
Assuntos
Entamoeba histolytica/imunologia , Entamebíase/prevenção & controle , Fígado/imunologia , Proteínas de Protozoários/imunologia , Vacinas Protozoárias/imunologia , Células Th1/imunologia , Vacinas de DNA/imunologia , Animais , Anticorpos Antiprotozoários/sangue , Antígenos de Protozoários/genética , Antígenos de Protozoários/imunologia , Cricetinae , Cisteína Endopeptidases/genética , Cisteína Endopeptidases/imunologia , Injeções Intradérmicas , Injeções Intramusculares , Interferon gama/metabolismo , Masculino , Mesocricetus , Plasmídeos , Proteínas de Protozoários/genética , Vacinas Protozoárias/administração & dosagem , Análise de Sobrevida , Fator de Necrose Tumoral alfa/metabolismo , Vacinas de DNA/administração & dosagem , Vacinas de DNA/genética , Fatores de Virulência/genética , Fatores de Virulência/imunologiaRESUMO
EhCPADH is an immunogenic, heterodimeric protein that is formed by EhCP112 (cysteine protease) and EhADH112 (adhesin), polypeptides involved in Entamoeba histolytica's cytopathic effect, target-cell adherence and phagocytosis. The EhCPADH complex is located in the plasma membrane and cytoplasmic vacuoles. Here, the independent expression of EhCP112 and EhADH112 in fibroblasts and hamsters was analysed. Also investigated was the immunological response in animals independently inoculated with plasmid pcDNA-Ehcp112, which carries the complete cysteine protease-encoding gene, or with plasmid pcDNA-Ehadh112, which carries the C terminus of the adhesin-encoding gene, or with a mixture of both. Both proteins were expressed in the plasma membranes of the transfected fibroblasts. EhCP112 was toxic for the mammalian cells. Proteins were also independently expressed in hamsters after inoculation with the plasmids. Their expression was indirectly evaluated by the presence of antibodies in the inoculated animals. Remarkably, co-immunization of the animals with the two DNA plasmids resulted in an earlier and higher anti-E. histolytica IgG induction than immunization with separate plasmids. In contrast, the cellular immune response was not noticeably improved by the plasmid mixture. Interestingly, protection against liver abscesses was detected only in animals that received the plasmid mixture and no protection was observed in hamsters independently inoculated with plasmid pcDNA-Ehcp112 or pcDNA-Ehadh112.