Characterization of an Invisible HIV-1 Circulating Recombinant Form (CRF149_01B) in China

In this study, by analyzing the available near full-length genome (NFLG) sequences of CRF55_01B, it was found that two of the NFLG sequences could not be clustered with other NFLG sequences. Recombination analysis and phylogenetic analysis suggested that these two NFLG sequences arose by recombination with subtype B based on CRF55_01B, rather than by recombination directly derived from CRF01_AE and subtype B. In addition, two other HIV-1 partial gene fragments found in the database shared the same characteristics as these two NFLG sequences in the key recombination region. These sequences may therefore represent a previously unrecognized circulating recombinant form (CRF), which has been named CRF149_01B. Evolutionary analyses suggested that CRF149_01B emerged between approximately 2005 and 2007. The discovery of CRF149_01B highlights the complexity of HIV recombinant evolution and advances the refinement of the HIV genotyping system. A deeper understanding of HIV-1 genetics will facilitate molecular tracing and provide a basis for studying the biological properties of HIV.