Identification of a new human immunodeficiency virus type 1 distinct from group M and group O

A highly divergent HIV-1 isolate, designated YBF 30, was obtained in 1995 from a 40-year-old Cameroonian woman with AIDS. Depending on the genes studied, phylogenetic analysis showed that YBF30 branched either with SIV(cpz-gab) or between SIV(cpz-gab) and HIV-1 group M. The structural genes and tat, vpr, and nef of YBF30 are approximately equidistant from those of HIV-1 group M and SIV(cpz-gab). In contrast, vif and rev are closer to HIV-1 group M, and vpu is highly divergent. Using a YBF30 V3 loop peptide enzyme immunoassay, we screened 700 HIV-1-positive sera collected in Cameroon; three reacted strongly with the YBF30 peptides and one was confirmed as being related to YBF30 by genetic analysis of a pol fragment. YBF30 is as distinct from SIV(cpz-gab) as it is from HIV-1 group M and can thus be considered as the prototype strain of a new human immunodeficiency virus group.