VH genes in tandem array comprise a repeated germline motif.

In a study of human VH gene heterogeneity, we have previously used sequence-specific oligonucleotide probes to demonstrate polymorphism of 56pl and three highly homologous VH3 germline elements. We now extend these findings with VH nucleotide sequences obtained from a person who possesses restriction fragments corresponding to each of these four VH3 genes. From a lambda-phage library of genomic DNA, distinct phage clones containing putative 56pl, hv3005, 1.9III, and hv3019b9 genes were selected by screening with oligonucleotide probes. PCR amplification, subcloning, and sequencing from the respective clones 3d216, 3d24, 3d28, and 3d277, yielded exact 56p1, hv3005, 1.9III, and hv3019b9 nucleotide sequences. A panel of oligonucleotide probes was shown to hybridize to these cloned VH3 genes with exact specificity, demonstrating the ability of the probes to predict the sequence of detected target DNA. Based on their chromosomal organization and their previously determined distribution in the population, these VH3 genes represent at least three distinct loci. From each of the VH3-containing phage clones, a VH4 element was also identified and sequenced. Linked to 3d24 and 3d28, respectively, were VH4 sequences identical to hv4005 and 1.9II, corroborating previous reports. The VH4 elements linked to 3d216 and 3d277 were distinct from published VH4 sequences. Nucleotide sequence homology was 97 to 99% among the VH3 sequences, and 93 to 99% among the VH4. These findings indicate that the VH3-VH4 gene pairs we have identified are a repeated germline motif, apparently resulting from multiple duplications of tandemly arrayed VH genes.