In view of the expansion of infection-dependent IgM binding to many different heterologous recombinant human proteins, the reactivity of sera populations toward the first panel of purified natural proteins from several unrelated sources was then tested to explore non-specific IgM binding of sera carp populations after preincubation of the sera with E. coli extracts to reduce non-specific IgM binding. This evidence concerns the gene CD40LG and infection.