Multiple sequence alignment of deduced amino acids of HIV-1 reverse transcriptase (RT) gene from mother H, who had given birth to infected twins, H1 and H2 (alignment shown in Figure 7). In the mother H sequences, each line refers to a clone identified by a clone number with M referring to mother. The mother sequences are aligned in reference to consensus RT sequence of HIV-1 subtype or clade B (CON B) shown at the top. The structural elements of RT are indicated above the alignment. Dots represent amino acid agreement with CON-B and substitutions are shown by single letter codes for the changed amino acid. Stop codons are shown as x and dashes represent gaps or truncated protein. Spanning arrowheads indicated above the alignment shows relevant amino acid motifs and domains required for RT activity.