The chimpanzee isolate SIV-CPZ was used as an outgroup. Phylogenetic analysis of the prt and env gene sequences. The patient's isolate is indicated by the arrow. Numbers at the branch nodes within the protease tree indicate bootstrap values. The nucleotide sequence distance among strains can be deduced from the horizontal branch lengths by using the included bar scale.
Vertical distances are for clarity only.
Unlike Group M viruses, which show greater heterogeneity in the regions flanking the V3 loop, the Group O viruses, including the CDC7755 strain, show substantial divergence within the loop itself. The pattern of potential N-glycosylation sites over the C2V3 region of the CDC7755 strain is consistent with that found among the Group O reference strains. The CONS-O represents the consensus amino acid sequence derived from the four strains presented in this alignment. This table may not fit on page unless printed in landscape mode. This is the first Group O case reported in the United States, and the presence of these infections here is believed to be exceedingly low.