{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T15:28:28Z","timestamp":1784302108859,"version":"3.55.0"},"reference-count":49,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2022,9,23]],"date-time":"2022-09-23T00:00:00Z","timestamp":1663891200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"<jats:p>CRF07_BC is one of the most prevalent HIV-1 strains in China, which contributes over one-third of the virus transmissions in the country. In general, CRF07_BC is associated with slower disease progression, while the underlying mechanisms remain unclear. Our study focused on envelope proteins (Env) and its V3 loop which determine viral binding to co-receptors during infection of cells. We studied a large dataset of 3,937 <jats:italic>env<\/jats:italic> sequences in China and found that CRF07_BC had a unique profile of predominantly single CCR5 tropism compared with CCR5 and CXCR4 dual tropisms in other HIV-1 subtypes. The percentages of the CXCR4-tropic virus in B (3.7%) and CRF01_AE (10.4%) infection are much higher than that of CRF07_BC (0.1%), which is supported by median false-positive rates (FPRs) of 69.8%, 25.5%, and 13.4% for CRF07_BC, B, and CRF01_AE respectively, with a cutoff FPR for CXCR4-tropic at 2%. In this study, we identified the first pure CXCR4-tropic virus from one CRF07_BC-infected patient with an extremely low CD4<jats:sup>+<\/jats:sup>T cell count (7 cells\/mm<jats:sup>3<\/jats:sup>). Structural analysis found that the V3 region of this virus has the characteristic 7T and 25R and a substitution of conserved \u201cGPGQ\u201d crown motif for \u201cGPGH\u201d. This study provided compelling evidence that CRF07_BC has the ability to evolve into CXCR4 strains. Our study also lay down the groundwork for studies on tropism switch, which were commonly done for other HIV-1 subtypes, for the long-delayed CRF07_BC.<\/jats:p>","DOI":"10.3389\/fimmu.2022.911806","type":"journal-article","created":{"date-parts":[[2022,9,23]],"date-time":"2022-09-23T13:43:11Z","timestamp":1663940591000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":9,"title":["Unique profile of predominant CCR5-tropic in CRF07_BC HIV-1 infections and discovery of an unusual CXCR4-tropic 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