Vaccinia virus: padronização de técnica para imunodiagnóstico e estudo da resposta imune humoral de bovinos

Abstract

The aims of this study were the standardization and validation of an immunoperoxidase monolayer assay (IPMA) for detection and quantification of IgG against Vaccinia virus (VACV) in cattle and to study the dynamics of the humoral immune response (HIR) against this pathogen in natural and experimentally infected bovines. The assay was validated by comparison with neutralization test (NT) results of 148 bovine serum samples; the results showed elevate accuracy, sensitivity, specificity and kappa index of agreement. Repeatability tests realized with 32 positive serum samples at the NT revealed high intraclass coefficient correlation. The IPMA was sensitive, specific and suitable for VACV screening. The study of HIR in VACV naturally infected cows and their calves demonstrated the peak of IgG and neutralizing antibodies (NA) in the first month of infection, with detection up to one year after the occurrence of outbreaks. The HIR of lactating cows experimentally infected with VACV-GP2 was also evaluated. The cows were monitored daily and serum samples were collected until the 60th day post infection. After this period, animals were separated in two treatment groups: re-infected and immunosuppressed. The curve of NA, IgG, IgG1 and IgG2 of these animals were determined. It was observed that the presence of antibodies partially protected reinfected cows against VACV.