Two new Ig VH gene families in Oncorhynchus mykiss.

Genes encoding the immunoglobulin heavy-chain variable region (Ig VH) in rainbow trout (Oncorhynchus mykiss) have been grouped into 11 families. While obtaining a baseline assessment of the various gene families utilized by trout in the production of secreted antibody, we discovered two new families. These proposed Ig VH families, Families XII and XIII, were rarely observed; only two VH sequence types were detected for each new family, suggesting that they may not be commonly used in response to antigens, or that the captive environment may not lead to typical exposures seen in the wild. Additionally, unlike preceding studies, we found at least one representative gene sequence for each of the 11 reported Ig VH gene families, possibly indicating that the repertoire of trout Ig VH gene families may be more universal among different stocks than previously realized.