Predominance of CXCR4 tropism in HIV-1 CRF14_BG strains from newly diagnosed infections
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Updated: May 9, 2026
Prediction of HIV-1 Coreceptor Usage (Tropism) by Sequence Analysis using a Genotypic Approach
Published on: December 1, 2011
Lucía Pérez-Álvarez1, Elena Delgado, Yolanda Vega
1HIV Biology and Variability Unit, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
Objectives:
R5-tropic viruses are associated with HIV-1 transmission and predominate during the early stages of infection. X4-tropic populations have been detected in ~50% of patients with late-stage disease infected with subtype B viruses. In this study, we compared the frequency of X4 tropism in individuals infected with HIV-1 CRF14_BG viruses, which have a V3 loop of subtype B, with a control group of individuals infected with subtype B viruses.
Methods:
Sixty-three individuals infected with HIV-1 CRF14_BG (n = 31) or subtype B (n = 32) were studied. Similar proportions of newly diagnosed and chronically infected individuals were included in the subtype B and CRF14_BG groups. V3 sequences were obtained and coreceptor tropism was predicted using the Geno2pheno[coreceptor] algorithm. V3 net charge and 11/25 rules were also used for coreceptor prediction.
Results:
Overall, X4 tropism was more frequent among individuals infected with CRF14_BG viruses (87.1%) than subtype B viruses (34.3%), a difference that was statistically highly significant (P = 0.00001). Importantly, the frequencies among newly diagnosed individuals were 90% and 13.3%, respectively (P = 0.0007). Characteristic amino acids in the V3 loop (T13, M14, V19 and W20) were identified at higher frequencies in CRF14_BG viruses (54%) than subtype B viruses (0%; P < 0.000001).
Conclusions:
CRF14_BG is the genetic form with the highest proportion of X4-tropic viruses reported to date in newly diagnosed and chronic infections. This suggests high pathogenicity for CRF14_BG viruses, potentially leading to rapid disease progression. CCR5 antagonists will be ineffective in most CRF14_BG-infected patients, even at early stages of infection.
