Rapid detection of SVC virus antigen in infected cell cultures and clinically diseased carp by the enzyme-linked immunosorbent assay (ELISA)

An ELISA was developed using a rabbit antiserum with high levels of binding antibody against SVC virus (SVCV). Modifications were made to the standard assay which increased the sensitivity and resulted in a rapid ELISA (rELISA) which could détéct SVCV antigen in cell cultures and in extracts from infected carp in approximately 1 h. When other cell-grown fish rhabdoviruses were tested, pike fry rhabdovirus (PFRV) antigen cross-reacted in the rELISA but only at a low level. Virus antigen was détécted by the rELISA in clinically and sub-clinically diseased carp during an SVC epizootic but the sensitivity of détéction of subclinical levels of virus was not as great as that of isolation of infectious virus in cell culture. However, antigen was détécted in some fish extracts which failed to yield infectious virus. Fresh extracts of organs from healthy carp were found to give false positive reactions in the rELISA. Kidney and liver extracts from these fish were found to contain a heat labile, non-specific binding factor and further modification of the rapid assay was undertaken which successfully reduced the effect of this factor.