Functional Analysis of Naturally Occurring Mutations in the Open Reading Frame of CCR5 in HIV-Infected Chinese Patients and Healthy Controls

Abstract

We studied polymorphism of the HIV coreceptor CC chemokine receptor (CCR) 5 in 1099 Chinese adults residing in Hong Kong, including 785 HIV-negative healthy donors and 314 HIV-positive patients. Ten mutants in the CCR5 open reading frame were identified, 7 of which were nonsynonymous. The frequencies of these alleles did not show a significant difference between HIV patients and healthy controls. G106R, Delta32, R223Q, 299(FS), and S336I were cloned from prevalent mutant genes, and their effects on HIV infection were analyzed by a series of in vitro experiments to determine their transcription levels, expression levels, conformational changes, and HIV coreceptor function. R223Q is the most prevalent CCR5 mutant in ethnic Chinese, with a frequency of 0.046, which does not affect HIV infection in vitro, however. The S336I mutant also does not affect its transcription, expression, or HIV coreceptor function. Similar to 299(FS), the mutant G106R located in the third transmembrane domain results in diminished HIV coreceptor function in vitro through conformation changes in ECL2.

Parental LTRs Are Important in a Construct of a Stable and Efficient Replication-Competent Infectious Molecular Clone of HIV-1 CRF08_BC

“…The p24 antigen level, indicative of HIV gene expression and viral replication, in the culture supernatant, was detected at 72 h post-transfection by an ELISA assay (bioMérieux; France), performed as described previously [30]. Viral infectivity in TZM-bl cells was determined by an X-Gal Staining assay, as described previously [31], [32].…”

C-C chemokine receptor type five (CCR5): An emerging target for the control of HIV infection

“…Carrington et al observed a decrease in variant co-receptor function while still maintaining the ability to bind to gp120 (Carrington et al, 1999). Analysis by Capoulade-Metay et al found no change in CCR5 expression or chemokine binding while Zhao et al found no effect on HIV infection in vitro or the CCR5 mRNA level (Capoulade-Metay et al, 2004, Zhao et al, 2005). …”

“…The G106R variant changes the residue hydrophobicity in the third TMD, resulting in reduced surface expression (Capoulade-Metay et al, 2004) without affecting levels of mRNA production (Zhao et al, 2005). The variant also decreases binding to chemokines and HIV.…”

HIV Type 1 Coreceptor Tropism, CCR5 Genotype, and Integrase Inhibitor Resistance Profiles in Vietnam: Implications for the Introduction of New Antiretroviral Regimens

“…R223Q is a naturally occurring polymorphism of the CCR5 gene, present in approximately 5-10% in Asian populations. 8 This variant is known to have little effect on either the ligand-binding capacity of CCR5, or the ability of HIV to utilize the molecule as a coreceptor, as is the case for the S336I polymorphism. The functional relevance of the W153C polymorphism is unknown.…”

“…Their existence follows from the discovery of natural mutations in the human CCR5 gene that confer varying degrees of resistance to HIV infection, most notably the CCR5D32 mutation. 8 Despite their relatively recent introduction to the ART arsenal, it is still possible for HIV to demonstrate resistance to each of these new drug classes. DRM conferring INI resistance were identified even during the clinical trials that led to RAL licencing 9 and more may be discovered as use of INIs increases.…”