Análise quantitativa e genética de parvovírus canino 2 em vacinas comerciais para cães

Abstract

The canine parvovirosis is a highly contagious disease and frequently fatal to dogs, in despite of the wide availability of vaccines. In Brazil, many modified live vaccines of the canine parvovirus type 2 (CPV-2) are currently used by veterinarians. However, there are several products on the market without a proven efficacy against local strains. The present study performed a phylogenetics analysis and determine the viral load of strains of CPV-2 in modified live vaccines commercialized in Brazil. Eighty vials of vaccines were obtained from manufacturer companies in the country. VP2 gene was sequenced in all the samples and the results were comparatively analyzed through phylogenetics. The PCR was performed in real time to determine the viral load in all vaccine vials. The phylogenetics results show that all strains of the CPV-2 vaccine came from the original genetic clade, from the first dissemination of CPV-2 that occurred more than 40 years ago. This clade had several genetic differences from the disseminated lineages. The vaccine viral DNA load reveals great differences among brands and even the absence of DNA in some vaccine bottles. These results support the possibility of the viral strains and the vaccine storage being probably associated with some vaccination failures and the occurrence of canine parvovirus outbreaks in Brazil. [resumo fornecido pelo autor]