Two different cDNA sequences for major histocompatibility complex (MHC
) class II beta chains from the channel catfish (Ictalurus punctatus)
have been identified. Homology between these sequences and those previ
ously identified as MHC class II B genes in other teleosts suggests th
ey represent alleles of the DAB locus. The inferred amino acid sequenc
es show strong evidence for a functional polypeptide chain with a pept
ide binding region. Southern blot analysis reveals polymorphism in the
MHC class II B gene(s) of the channel catfish and suggests the presen
ce of two to four genes. (C) 1997 Elsevier Science Ltd.