Multiple sequence alignment of deduced amino acids of HIV-1 reverse transcriptase gene (RT) from infected twin infants, H1 and H2 of mother H (alignment shown in Figure 6). In the alignment, the top sequence is the consensus subtype B RT sequence (CON B) and the bottom sequences are of infants H1 and H2 represented by I and clone numbers. 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. Relevant amino acid motifs and domains essential for RT activity are shown by spanning arrowheads indicated above the alignment.