Protein polymorphism of an isoform of the third complement component in the common carpCyprinus carpio

摘要

Polymorphism of immune-related genes has the potential to be utilized as a genetic marker to survey the disease-resistant fish population. The complement is a major factor functioning both in innate and adaptive immune systems. In the present paper itwas found that C3-H1, a major isoform of the complement component C3 of carp, exhibits four genetic variants defined as electro-phoretic mobility, and that the four variants have different hemolytic activity. Carp serum was electro-phoresed on an agarose gel and blotted onto a nitrocellulose membrane, and C3 bands were detected by immunoblotting using monoclonal antibody specific to intact a-chain of carp C3-H1 isoform. Four C3-H1 variants, designated I, II, III and IV, with different mobility were detected, and the phenotypes II and II/IV were dominant. Each of four C3-H1 variants free of cross-contamination was purified from carp sera and examined for the hemolytic activity. It was found that C3-H1-I had the highest specific activity, which was approximately fourfold higher than that of C3-H1-II, which had the lowest activity. The results suggest the possibility that carp individuals possessing a different type of C3-H1 variants have a different level of complement activity, and that the C3-H1 polymorphism can possibly be useful to screen fish with a higher level of innate immune defense.