High prevalence of CXCR4 usage among treatment-naive CRF01_AE and CRF51_01B-infected HIV-1 subjects in Singapore

• Published in: BMC infectious diseases Vol. 13; no. 1; p. 90
• Main Authors: Ng, Kah Ying, Chew, Kuan Kiat, Kaur, Palvinder, Kwan, Joe Yap, Khong, Wei Xin, Lin, Li, Chua, Arlene, Tan, Mei Ting, Quinn, Thomas C, Laeyendecker, Oliver, Leo, Yee Sin, Ng, Oon Tek
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 19-02-2013; BioMed Central; BMC
• Subjects: Adolescent; Adult; AIDS treatment; Analysis; Care and treatment; Chemokine receptors; Child; CXCR4 usage; Development and progression; Ethnicity; Female; Genotype; Health aspects; HIV; HIV (Viruses); HIV Envelope Protein gp120 - genetics; HIV infection; HIV Infections - epidemiology; HIV Infections - immunology; HIV Infections - virology; HIV-1; HIV-1 - classification; HIV-1 - genetics; HIV-1 - metabolism; Hospitals; Human immunodeficiency virus; Human immunodeficiency virus 1; Humans; Infections; Male; Medical research; Medical tests; Medicine, Experimental; Middle Aged; Polymerase chain reaction; Prevalence; Receptors, CCR5 - metabolism; Receptors, CXCR4 - metabolism; Risk factors; Singapore - epidemiology; Studies; treatment-naïve; Viral Tropism; Viruses; Young Adult; Singapore
• ISSN: 1471-2334; 1471-2334
• DOI: 10.1186/1471-2334-13-90

Recent studies suggest HIV-1 inter-subtype differences in co-receptor usage. We examined the correlation between HIV-1 subtype and co-receptor usage among treatment-naïve HIV-1 subjects in Singapore. Additionally, we investigated whether the subtype co-receptor association was influenced by stage of infection.
V3 sequences of HIV-1 envelope protein gp120 were obtained from 110 HIV treatment-naïve patients and genotypic co-receptor tropism determination was performed using Geno2pheno. Two false-positive rate (FPR) cut-offs, 10% and 5.75% were selected for tropism testing.
Subtype assignment of viral strains from 110 HIV-infected individuals based on partial sequencing of HIV-1 pol, gp120 and gp41 were as follows: 27 subtype B, 64 CRF01_AE, 10 CRF51_01B, and 9 other subtypes. At FPR=10%, 10 (100%) CRF51_01B-infected subjects and 26 (40.6%) CRF01_AE-infected subjects had CXCR4-using virus, compared to 7 (25.9%) subtype B subjects and 1 (11.1%) CRF33_01B-infected subject (P < 0.001). At FPR=5.75%, 10 (100%) CRF51_01B-infected subjects and 20 (31.3%) CRF01_AE-infected subjects had CXCR4-using virus, compared to 4 (14.8%) subtype B and 1 (11.1%) CRF33_01B-infected subjects (P < 0.001). Among those with evidence of seroconversion within 2 years prior to study enrolment, 100% of CRF51_01B-infected subjects had CXCR4-using virus, independent of Geno2pheno FPR.
CRF51_01B and CRF01_AE-infected individuals have higher prevalence of CXCR4-usage compared to subtype B infected individuals. Further studies examining these differences could help optimise the use of CCR5-antagonist in populations with these subtypes, and increase our understanding of HIV-1 biology.