Baboon immunoglobulin variable region heavy chains: identification of genes homologous to members of the human IGHV1-IGHV7 subgroups.

Baboons are increasingly used as animal models in studies that require the assessment of specific antibody responses. The complete analysis of these responses includes the characterization of antibody variable region genes and their usage. Therefore, we cloned and sequenced a total of 27 immunoglobulin variable region heavy chain (IGHV) genes using cDNA obtained from a single baboon (Papio cynocephalus anubis). Comparison of baboon and human IGHV sequences shows that the percent of identity varies between 86% and 96% at the nucleotide level and between 80% and 95% at the amino acid level. The various baboon IGHV genes can be grouped into one of seven subgroups corresponding to the human IGHV1-IGHV7 subgroups. The only baboon cDNA sequence belonging to the IGHV7 subgroup is homologous to the human IGHV7-81 gene, for which no transcripts have been described. Similarly to their human counterparts, all baboon IGHV genes cluster into three clans, with one clan including the IGHV1, IGHV5 and IGHV7 subgroups, one clan including the IGHV2, IGHV4 and IGHV6 subgroups, and one clan including the IGHV3 subgroup. These data indicate that baboons may represent valuable models to analyze the antibody repertoire generated in response to immunization strategies developed for human use.