RESUMO
A Nepalese heterozygous carrier of a CCR5 mutant, designated 118delF, was characterized. There was a 3 basepair deletion at 352-354 in the CCR5 open reading frame, resulting in the deletion of the phe-118 residue located in the third transmembrane domain. The mutant protein has retained antigen specificity near the third extra-cellular loop (ECL3), but that of ECL2 is markedly reduced. The mutation has also abrogated HIV co-receptor activity. Clinically, the HIV disease had progressed slowly.
Assuntos
Infecções por HIV/genética , HIV-1/genética , Receptores CCR5/genética , Receptores de HIV/genética , Sequência de Aminoácidos , Infecções por HIV/imunologia , HIV-1/imunologia , Heterozigoto , Humanos , Mutação/genética , Mutação/imunologia , RNA Mensageiro/análise , RNA Viral/análise , Receptores CCR5/imunologia , Receptores de Quimiocinas/genética , Receptores de Quimiocinas/imunologia , Receptores de HIV/imunologia , Deleção de SequênciaRESUMO
We have previously reported that a subunit protein vaccine based on the receptor-binding domain (RBD) of severe acute respiratory syndrome coronavirus (SARS-CoV) spike protein and a recombinant adeno-associated virus (rAAV)-based RBD (RBD-rAAV) vaccine could induce highly potent neutralizing Ab responses in immunized animals. In this study, systemic, mucosal, and cellular immune responses and long-term protective immunity induced by RBD-rAAV were further characterized in a BALB/c mouse model, with comparison of the i.m. and intranasal (i.n.) routes of administration. Our results demonstrated that: 1) the i.n. vaccination induced a systemic humoral immune response of comparable strength and shorter duration than the i.m. vaccination, but the local humoral immune response was much stronger; 2) the i.n. vaccination elicited stronger systemic and local specific cytotoxic T cell responses than the i.m. vaccination, as evidenced by higher prevalence of IL-2 and/or IFN-gamma-producing CD3+/CD8+ T cells in both lungs and spleen; 3) the i.n. vaccination induced similar protection as the i.m. vaccination against SARS-CoV challenge in mice; 4) higher titers of mucosal IgA and serum-neutralizing Ab were associated with lower viral load and less pulmonary pathological damage, while no Ab-mediated disease enhancement effect was observed; and 5) the vaccination could provide long-term protection against SARS-CoV infection. Taken together, our findings suggest that RBD-rAAV can be further developed into a vaccine candidate for prevention of SARS and that i.n. vaccination may be the preferred route of administration due to its ability to induce SARS-CoV-specific systemic and mucosal immune responses and its better safety profile.
Assuntos
Glicoproteínas de Membrana/administração & dosagem , Glicoproteínas de Membrana/imunologia , Síndrome Respiratória Aguda Grave/prevenção & controle , Proteínas do Envelope Viral/administração & dosagem , Proteínas do Envelope Viral/imunologia , Vacinas Virais/administração & dosagem , Vacinas Virais/imunologia , Administração Intranasal , Animais , Formação de Anticorpos , Células 3T3 BALB , Dependovirus/genética , Humanos , Imunidade nas Mucosas , Imunoglobulina A/imunologia , Pulmão/imunologia , Glicoproteínas de Membrana/genética , Camundongos , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/efeitos dos fármacos , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/fisiologia , Glicoproteína da Espícula de Coronavírus , Baço/imunologia , Linfócitos T Citotóxicos/imunologia , Vacinação , Proteínas do Envelope Viral/genética , Vacinas Virais/genética , Replicação Viral/efeitos dos fármacosRESUMO
Development of an effective vaccine for severe acute respiratory syndrome (SARS) remains to be a priority to prevent possible re-emergence of SARS coronavirus (SARS-CoV). We previously demonstrated that the receptor-binding domain (RBD) of SARS-CoV S protein is a major target of neutralizing antibodies. This suggests that the RBD may serve as an ideal vaccine candidate. Recombinant adeno-associated virus (rAAV) has been proven to be an effective system for gene delivery and vaccine development. In this study, a novel vaccine against SARS-CoV was developed based on the rAAV delivery system. The gene encoding RBD was cloned into a pAAV-IRES-hrGFP plasmid. The immunogenicity induced by the resulting recombinant RBD-rAAV was evaluated in BALB/c mice. The results demonstrated that (1) a single dose of RBD-rAAV vaccination could induce sufficient neutralizing antibody against SARS-CoV infection; (2) two more repeated doses of the vaccination boosted the neutralizing antibody to about 5 times of the level achieved by a single dose of the immunization and (3) the level of the antibody continued to increase for the entire duration of the experiment of 5.5 months. These results suggested that RBD-rAAV is a promising SARS candidate vaccine.