RESUMO
The emergence of new infectious bronchitis virus (IBV) genotypes or serotypes along with the poor cross-protection observed among IBV serotypes have complicated the avian infectious bronchitis (IB) control programs in different geographic regions. In Cuba, the lack of genetic information regarding IBV and the increasing epidemiological importance of this virus in Cuban chicken flocks demand further characterization of IBV isolates. In the present work, studies of genetic diversity and phylogenetic relationships among recent IBV isolates from Cuban chicken flocks showing respiratory disorders were performed. Two putative genotypes genetically different to the Massachusetts genotype H120 strain used in the Cuban vaccination program were found in the flocks assessed. In addition, a potential nephropathogenic IBV isolate was found by first time in Cuba.
Assuntos
Galinhas , Doenças Transmissíveis Emergentes/veterinária , Infecções por Coronavirus/virologia , Genótipo , Vírus da Bronquite Infecciosa/genética , Doenças das Aves Domésticas/virologia , Animais , Infecções por Coronavirus/epidemiologia , Cuba/epidemiologia , Regulação Viral da Expressão Gênica/fisiologia , Filogenia , Doenças das Aves Domésticas/epidemiologia , Proteínas Virais/genética , Proteínas Virais/metabolismoRESUMO
Rabbit hemorrhagic disease (RHD) is a contagious and highly lethal viral disease of rabbits that spreads rapidly and infects animals by nasal, conjunctival and oral routes. Therefore, this experiment was undertaken to study the immune response generated after intranasal (i.n.) vaccination with the recombinant VP60 capsid protein from rabbit hemorrhagic disease virus (RHDV) expressed at high levels in Pichia pastoris. Groups of BALB/c mice were immunized with three doses of purified VP60 protein (Group 1), VP60 formulated within the cell debris fraction of the transformed yeast (Group 2) and placebo (Group 3) by intranasal route. Mice were also intramuscularly injected with purified VP60 protein (Group 4). A rapid antibody response specific against rabbit hemorrhagic disease virus was observed in all the experimental groups, except in Group 3, as detected by ELISA. The highest titers were found 60 days after the first immunization. Mice from Group 1 showed the highest IgG response (p<0.05) and the most balanced profile of IgG1, IgG2a and IgG2b subclasses. IgA titers specific to the virus were found only in animals from this group, which also developed the highest specific lymphocyte proliferative response. Interferon-gamma (IFN-gamma) and interleukin-12 (IL-12) gene expression was also detected after an ex vivo-specific stimulation of mice from Groups 1 and 4. These data demonstrated the capacity of VP60 protein expressed in P. pastoris to elicit a potent humoral and cell-mediated immune response following an intranasal immunization scheme.