CCR2 allele polymorphisms in 15 Chinese ethnic populations

Impact of CCR2 and SDF1 polymorphisms on disease progression in HIV-infected subjects in Thailand

BACKGROUND

The genotypic polymorphisms of CCR5, CCR2, and SDF1 were analyzed to determine their impact as potential confounders with regard to disease progression because of the role that host genetic factors appear to be involved in determining rates of disease progression.

METHODS

Genomic DNA was extracted from Ethylenediaminetetraacetate whole blood using Qiagen DNA extraction kit. The amplification of CCR5, CCR2, and SDF1 genes was performed by PCR.

RESULTS

Two hundred and twenty-one samples were genotyped for the CCR5, CCR2, and SDF1 mutation. Among these, all (100%) were identified as wild type for CCR5. All were then investigated considering the impact on CD4+ T-cell counts. Samples were divided into two groups based on the CD4+ T-cell numbers. It revealed that in the group of CD4+ T-cell counts ≥200 cells/μl, 15 were found for the homozygous for SDF1 gene (3'A/3'A) whereas one was found in the group of CD4+ T-cell counts <200 cells/μl. Homozygosity for the CCR2 polymorphisms (64I/64I) were five in the group of CD4+ T-cell counts ≥200 cells/μl and none were found in the group of CD4+ T-cell counts <200 cells/μl. These results demonstrated that there was a significant association between CD4+ T-cell numbers and CCR2 and SDF1 polymorphisms (P < 0.001).

CONCLUSIONS

The mutation of CCR2 and SDF1 genes showed a significant difference in the distribution of CD4+ T-cell numbers (P < 0.001) whereas mutation of chemokine coreceptor CCR5 was not appeared to be associated with the impact of CD4+ T-cell counts.

Genetic correlates influencing immunopathogenesis of HIV infection

Variability to HIV infection, its progression as well as responsiveness to antiretroviral therapy (ART) is observed among individuals including viraemia controllers or exposed uninfected, rapid versus slow progressors and ART responders compared to non responders. This differential responsiveness/vulnerability to HIV-1 is governed by multiple host genetic factors that include HLA, cytokines, chemokines, their receptors and others. This review highlights the influence of these genetic factors on HIV/AIDS outcome; however, in India, the information in this area is very limited and most of these genetic studies have been conducted in Caucasian and South African populations. Considering, the population specific differences in the frequencies of protective or susceptibility favouring alleles and their influence on the disease outcome, it is of utmost importance to strengthen ongoing efforts towards defining largely unknown genetic propensity in Indian population, particularly by recruitment of large cohorts of well categorized exposed uninfected individuals, rapid, long term non progressors and elite viraemic controllers. Multi-parametric analysis of these potentially interactive immunogenetic variables in these cohorts may help to define potential targets for diagnostics and therapy in a population specific manner.

Distribution of CCR5-Delta32, CCR5m303A, CCR2-64I and SDF1-3'A in HIV-1 infected and uninfected high-risk Uighurs in Xinjiang, China

BACKGROUND

Genetic variants of the genes encoding HIV-1 co-receptors and their ligands, CCR5-Delta32, CCR5m303A, CCR2-64I and SDF1-3'A, are implicated in the susceptibility to HIV-1 infection, and the prevalence of these mutations varies by ethnicity. However, little is known about their distribution in Uighurs.

OBJECTIVES

This study aimed at characterizing the frequency of these HIV-related gene variants in a high-risk Uighur population.

STUDY DESIGNS

A total of 251 HIV-1 seropositive and 238 seronegative high-risk Uighurs were recruited and their genotypes of CCR5-Delta32, CCR5m303A, CCR2-64I and SDF1-3'A were analyzed by PCR and PCR-ligase detection reaction (PCR-LDR).

RESULTS

The allelic frequency of CCR5-Delta32, CCR5m303A, CCR2-64I and SDF1-3'A was 4.40%, 2.66%, 25.66% and 57.36%, respectively, in this population. Apparently, the Uighur population has low frequency of CCR5-Delta32 and CCR5m303A, but high frequency of CCR2-64I and SDF1-3'A. While there was no significant difference in the frequency of CCR5-Delta32, CCR2-64I and SDF1-3' A between HIV-1 seropositive and seronegative groups the frequency of CCR5m303A in HIV-1 seropositive group was significantly higher than that in seronegative group (P=0.006, OR=3.982 and 95%CI 1.514-10.476).

CONCLUSIONS

Our data suggest that the CCR5-Delta32, CCR2-64I and SDF1-3'A variants may have limited effect on protecting from HIV-1 infection in Uighurs. Rather, the CCR5m303A may be associated with the risk for HIV-1 infection in high-risk Uighurs.

Immunogenetic basis of HIV-1 infection, transmission and disease progression

Susceptibility to HIV-1 infection and rate of disease progression to AIDS are complex traits modulated by environmental and genetic factors. Studies on large AIDS cohorts and their meta-analyses have identified numerous AIDS restriction genes that regulate HIV cell entry (particularly chemokine co-receptors and their ligands), acquired and innate immunity (major histocompatibility complex (MHC), killer immunoglobulin-like receptors (KIRs), and cytokines) and others that influence outcome of HIV infection. However, vast inter-individual variability is often observed and some rare individuals like 'long-term non-progressors (LTNPs) or exposed uninfected' (EUs) appear to be protected due to natural resistance. A better understanding of genetic basis of such a 'natural resistance' to infection would bear important implications in designing therapeutic vaccine designs. The genetic variants that could limit AIDS vary in different populations. We have studied genetic variations in the MHC, cytokines and CCR2-CCR5 loci in the Asian-Indian HIV-infected population and compared with other global populations.

Distribution of CCR2 polymorphism in HIV-1-infected and healthy subjects in North India

Substitution of V64I in CCR2 relates to delayed progression to AIDS and protects against HIV-1 infection. We examined the distribution of V64I in HIV-infected and healthy North Indian subjects. No significant difference in the allele or genotype distribution of CCR2 V64I polymorphism was observed, indicating that there is no association between CCR2 V64I polymorphism and susceptibility to HIV infection in North Indian population.