Innate immune response of channel catfish Ictalurus punctatus mannose-binding lectin to channel catfish virus (CCV)

The channel catfish virus (CCV) is a pathogenic herpesvirus that infects channel catfish Ictalurus punctatus in pond aquaculture in the southeastern USA. Mannose-binding lectin (MBL), an innate immune protein, could play an important role in the innate response of channel catfish by binding to CCV. Cell cultures of CCV were grown in channel catfish ovary cells (CCOC). A dot-immunoblot enzyme-linked immunosorbent assay was done to determine the binding ability of 5 mo old channel catfish serum MBL (26.2 µg ml-1) to CCOC infected with CCV. Two separate nitrocellulose membrane blotting techniques were done using uninfected and infected CCOC. The uninfected CCOC decreased by 29.3 and 33.4% in their binding of channel catfish MBL when compared with infected CCOC using the 2 membrane procedures. The combined average binding ability of channel catfish MBL towards infected CCOC was therefore 31.4% greater when comparing the infected and uninfected CCOC. Normalization equation values of MBL for the 5 mo old catfish were compared for the 2 membrane binding procedures. The 2 normalization values were very close (142 and 150) in binding ability of MBL to the infected CCOC. The 5 mo catfish serum had twice the concentration of MBL (26.2 µg ml-1) compared to 7 mo catfish serum (13.2 µg ml-1), and the binding percentage of 5 mo serum was 2.4 times greater in infected than in uninfected cells. This demonstrates that the binding of channel catfish serum MBL to CCV is concentration dependent and is related to serum concentrations of MBL.