Nucteotide (A) and deduced amino acid (B) sequences of the VH genes utilized by the natural human mAb. In each duster, the top sequence is given for comparison and represents the germline VH gene displaying the highest degree of identity to the expressed VH genes of the cluster The 4.33, VH4.2 1 , and 3d279d genes belong to the VHIV family. The leader region sequence of the VH4.21 is not available, that of the V58 gene leader region is provided instead. The VH26c gene is a member of the VHIII family. Dashes indicate identities. Solid lines on the top of each duster depict CDR. Small letters denote untranslated sequences Asterisks indicate translation initiation codons. The present sequences are available form EMBL/GenBank/DDBJ under accession numbers L25291, L25292, L25293, and L25294.