Diagnostic efficiency of rabies antigen for indication of post-vaccination antibodies
The purpose of this study to evaluate diagnostic efficiency of isolated rabies antigen to assess the intensity of immunity in animals vaccinated against rabies. In the course of the study, we analyzed main immunochemical characteristics of antigenic fractions of the rabies virus isolated in a 15-50% step gradient of sucrose density and obtained by reprecipitation with a saturated solution of ammonium sulfate. It was found that the major fraction of the purified antigen is located in the region of 66.2 - 67 kDa; also, the isolated preparation is characterized by a minimum content of secondary proteins. As a result of determining the serological activity of antigenic fractions by the indirect ELISA method, their optimum concentrations for sorption on polystyrene plates were determined. A total of 90 sera of immunized cattle, small cattle and dogs selected in the regions of Tatarstan, Bashkortostan, and the Kirov Region of the Russian Federation were investigated. As a result of the study of sera in ELISA, the titers of post-vaccination antibodies corresponding to the range of 1.25-20 IU / ml were determined; in 97.7% of sera, the antibody level exceeded the recommended protective level (0.5 IU / ml). As a control test, we used a neutralization reaction on white mice; when comparing the results of RN and ELISA, a significant positive correlation was found. The obtained results testify to the high diagnostic efficiency of antigenic fractions and prospects of their use for the purpose of mass screening of the state of specific immunity in vaccinated animals.