Development and evaluation of polyclonal antisera for detection of the IgM heavy chain of multiple fish species

•Two synthetic peptides (fish IgH-1 and fish IgH-2) were designed based on the conserved sequence of fish Ig heavy-chain.•Anti-fish IgH-1 and anti-fish IgH-2 peptide polyclonal antisera were produced in this study.•Anti-fish IgH-1 showed reactivity to monomeric and polymeric forms of fish IgM by Western blotting.•Two peptide polyclonal antisera are not applicable for immunoglobulin detection by ELISA.

Antibodies are widely considered to be essential tools for detection of immune responses in various fish species. Here we produced the peptide polyclonal antisera (anti-fish IgH-1 and anti-fish IgH-2) to detect IgM of various fish species. The peptides were designed based on the conserved sequence of the fish immunoglobulin heavy chains of seven fish species (Japanese flounder, seabream, yellowtail, carp, rainbow trout, hybrid sturgeon and banded houndshark). By Western blotting, anti-fish IgH-1 antiserum detected the IgMs of all fish species except banded houndshark. Anti-fish IgH-2 antiserum clearly reacted with the IgMs of only three of the fish species (seabream, yellowtail and rainbow trout). Attempts to use the antisera to measure fish antibody titer by ELISA were unsuccessful. These results demonstrate that anti-fish IgH-1 peptide polyclonal antiserum is a potentially applicable tool for detecting immunoglobulins in various fish species by Western blotting.