Random amplified polymorphic DNA (RAPD) fingerprinting resolves species ambiguity of domesticated clown fish (genus: Amphiprion, family: Pomacentridae) from India

A previously developed monoclonal antibody (mAb) specific for the heavy chain of hybrid striped bass (HSB) Morone chrysops * M. saxatilis immunoglobulin was used in an assay to detect the humoral response to antigens of Streptococcus iniae. In order to validate this assay, an anti-S. iniae antibody was produced in HSB by immunization with formalin-killed cells of S. iniae mixed with Freundʹs complete adjuvant (FCA). After boosting with cells mixed with Freundʹs incomplete adjuvant (FIA), fish were challenged with live S. iniae by i.p. injection. This resulted in mortalities of 100%, 13% and 7% for nonimmunized, immunized and non-challenged fish respectively. Live S. iniae were recovered only from moribund non-immunized challenged fish, indicating that the immunization conferred protection against S. iniae. Sera were taken at 28 and 42 days post challenge and anti-S. iniae antibody was measured by both agglutination and indirect ELISA. Titres of anti-S. iniae antibody increased only in the immunized group as measured by agglutination and ELISA. Serum complement measured in the final bleeding was significantly higher in the immunized group. Western blotting using immune HSB serum indicated that the predominant antigen in this case was the high molecular weight polysaccharide of S. iniae.