Serology based immunological cross-reactivity among various isolates of streptococcus agalactiae from mastitic buffaloes

Abstract

To measure the degree of immunological cross-reactivity among different isolates of Streptococcus agalactiae from mastitic cases of buffaloes and cows in four districts (Faisalabad, Jhang, Toba Tek Singh and Sargodha), two tests were used. The isolates of Streptococcus agalactiae obtained from mastitic animals from these districts were purified on Edward’s medium. Hyper immune sera were raised by injecting 1.2 x 109 cfu/ml I/V of the isolates separately into rabbits. The sera thus raised were tested for in vitro immunological cross-reactivity through counter immuno-electrophoresis and bacterial agglutination test. Eight Streptococcus agalactiae isolates were selected and named A, B, C, D, E, F, G and H. In the bacterial agglutination test, all variants were similar antigenically and showed positive reactions, but a few reactions were negative, so the cross-reactivity among the variants was (93.75 %) with respect to the positive reactions. The percentage of negative reactions was (6.25 %). The cross-reactivity among the Str. agalactiae isolates was 98.43% by modified counter immuno-electrophoresis assay.