Chemokine receptor CCR2b 64I polymorphism and its relation to CD4 T-cell counts and disease progression in a Danish cohort of HIV-infected individuals. Copenhagen AIDS cohort

The Distribution of CCR2-64I, SDF1-3'A and MCP1-2518 G/A Genes Polymorphism in a Specific High Risk Group from the Northeastern States West Bengal, and Gorkha Population in India

We studied the prevalence and effects of host genetic polymorphisms for the three AIDS restriction genes (ARGs) namely CCR2-64I, SDF1-3'A and MCP1-2518 G/A for HIV infection and progression to AIDS using PCR-RFLP analysis on a total of 568 HIV seronegative serum samples collected from a specific high risk and young population hailing from the seven Northeastern states of India (n = 346), West Bengal (n = 96) and Gorkha population (n = 101). In addition, 181 HIV seropositive cases of which 92 inpatient cases in a large tertiary care hospital located at Kolkata were included in the study. HIV prevalence in our study group was 0.52 %. Four cases seroconverted, 25 cases progressed to AIDS and 05 died during the follow up period of 41 months. The genotype percentage of CCR2-64I, SDF1-3'A and MCP1-2518 G/A in the Northeastern states were 18.5, 40.3 and 54 % respectively in the seronegative population. Allele frequencies for SDF1-3'A in Northeastern states were significantly higher as compared to the Gorkha (21 %) and the North Indian population (24 %). Relative Hazard values were more than 0.9 for progression to AIDS and death. Kaplan-Meier survival analysis using Cox proportional regression model did not reveal any significant survival benefit (p value <0.05) for any of the 3 ARGs individually or in combination either to seroconversion or disease progression. This is the first study on host genetic polymorphism amongst the Eastern, Northeastern and Gorkha regions in India. We are also the first to report the MCP1-2518 G/A polymorphism in India that is known to increase the rate of neuropsychological impairment (NPI) in AIDS patients.

CCR5 haplotypes and mother-to-child HIV transmission in Malawi

Background

CCR5 and CCR2 gene polymorphisms (SNPs) have been associated with protection against HIV transmission in adults and with delayed progression to AIDS. The CCR5 Δ32 deletion and SNP -2459G are associated with reduced expression of the CCR5 protein.

Methodology/Principal Findings

We investigated the association between infant CCR2/CCR5 diplotype and HIV mother to child transmission (MTCT) in Malawi. Blood samples from infants (n = 552) of HIV positive women who received nevirapine were genotyped using a post-PCR multiplex ligase detection reaction and haplotypes were identified based on 8 CCR2/CCR5 SNPs and the open reading frame 32 base pair deletion. Following verification of Hardy-Weinberg equilibrium, log linear regression was performed to examine the association between mutations and MTCT. Overall, protection against MTCT was weakly associated with two CCR5 SNPs, -2459G (Risk ratio [RR], 0.78; confidence interval [CI], 0.54–1.12), and the linked CCR5 -2135T (RR, 0.78; CI, 0.54–1.13). No child carried the CCR5 Δ32 SNP. Maternal Viral Load (MVL) was found to be an effect measure modifier. Among mothers with low MVL, statistically significant protection against MTCT was observed for -2459G (RR, 0.50; CI, 0.27–0.91), and -2135T (RR, 0.51; CI, 0.28–0.92). Statistically significant protection was not found at high MVL.

Conclusions/Significance

Results from this study suggest that CCR5 SNPs -2459G and -2135T associated with reduced receptor expression protect against MTCT of HIV at low MVLs, whereas high MVLs may over-ride differences in coreceptor availability.

Effect of Genetic Variants of CCR2 and CCL2 on the Natural History of HIV-1 Infection

BACKGROUND AND OBJECTIVES

Polymorphisms in the genes that encode for the CCR2 chemokine receptor and its natural ligand CCL2 have been shown to influence the natural history of HIV-1 infection, although data are inconsistent. Our aim was to determine whether functionally active CCR2 and CCL2 genetic variants influence the risk of infection and disease progression in a cohort of white Spaniards.

PATIENTS AND METHODS

This was a multicenter genetic association case-control study. Two single nucleotide polymorphisms (SNPs), V64I (G > A) of the CCR2 gene and -2518 (A > G) of the CCL2 gene, were assessed in 318 individuals: 73 HIV-1-infected long-term nonprogressors (LTNPs) of >16 years duration, 109 HIV-1-infected usual progressors (UPs), 36 heavily exposed to HIV-1 but uninfected individuals (EUs), and 100 control subjects. The distribution of the CCR5Delta32 allele was also assessed. Genotyping was performed using polymerase chain reaction (PCR) restriction fragment length polymorphisms (RFLPs) or PCR and automatic sequencing analysis methods on white blood cell DNA. Genotype and allele frequencies were compared by the chi2 test and the Fisher exact test.

RESULTS

CCR2 genotype distribution and allele frequencies showed nonsignificant differences between groups. The distribution of CCL2 alleles showed no significant differences between groups. HIV-1-infected individuals had, however, a significantly higher prevalence of the variant homozygous CCL2 GG genotype compared with EUs (P = 0.02). This result persisted when we studied only individuals with wild-type CCR5. Genotype and allele distribution of CCL2 was similar in HIV-1-infected UPs and LTNPs.

CONCLUSIONS

In our cohort of white Spaniards, homozygosity for the variant CCL2-2518GG genotype is overrepresented in HIV-1-infected subjects.

Genetics of resistance to HIV infection: Role of co-receptors and co-receptor ligands

Susceptibility to HIV infection and AIDS progression is variable among individuals and populations, and in part genetically determined. Genetic variants of genes encoding HIV co-receptors and their chemokine ligands have been described, and some of these variants were associated with resistance to HIV infection and/or disease progression. We review here the reported data regarding the variants of the CCR5, CCR2, CX3CR1, MIP-1alpha/CCL3, MIP-1beta/CCL4, RANTES/CCL5 and SDF-1/CXCL12 genes. The Delta32 deletion mutant of CCR5, resulting in a non-functional receptor not reaching the cell surface, is unambiguously associated with strong, although incomplete, resistance to HIV infection for homozygotes, and retarded progression for heterozygotes. Specific haplotypes encompassing the CCR5 and CCR2 loci, and the copy number of the CCL3L1 gene, have also been convincingly correlated with delayed progression. For other gene variants, involving CXCL12/SDF-1 and CX3CR1, conclusive evidence for their relevance in the frame of HIV susceptibility is still lacking.

Global human genetics of HIV-1 infection and China

Genetic polymorphisms in human genes can influence the risk for HIV-1 infection and disease progression, although the reported effects of these alleles have been inconsistent. This review highlights the recent discoveries on global and Chinese genetic polymorphisms and their association with HIV-1 transmission and disease progression.

Prevalence of alleles associated with HIV resistance in Russia

Genetic polymorphisms of CCR5, CCR2, and SDF1 genes have been associated with resistance during human immunodeficiency virus type 1 (HIV-1) infection and disease progression. In the present report, we studied the frequency and co-occurrence of CCR5Delta32, CCR5-59029A/G, CCR2-64I, and SDF1-3'A allelic variants among HIV-1-seronegative individuals (n = 171) in Moscow. Observed allelic frequencies were 0.0906 [95% confidence interval (CI), 0.06-0.1212] for CCR5Delta32, 0.4072 (95% CI, 0.3542-0.4602) for CCR5-59029G, 0.1061 (95% CI, 0.0728-0.1394) for CCR2-64I, and 0.2218 (95% CI 0.1715-0.2721) for SDF1-3'A. A significant linkage disequilibrium (p = 0.0034) between CCR2-64I and SDF1-3'A alleles was observed.

Association of highly active antiretroviral therapy failure with chemokine receptor 5 wild type

OBJECTIVES

Approximately 10% of HIV-infected patients fail to respond properly to highly active antiretroviral therapy (HAART). Among other factors, genetic variants of chemokine receptors have been shown to modify the course and outcome of HIV infection. Our objective was to investigate whether a failure of virological response is associated with polymorphisms of the chemokine receptors or cofactors.

METHODS

A total of 256 HIV-infected patients receiving HAART and 221 healthy controls were analysed for the chemokine receptor 5 (CCR5)-Delta32-bp, stromal derived factor 1 (SDF1)-3'A and chemokine receptor 2 (CCR2)-64I polymorphisms. Treatment failure was defined as failure to lower the viral load below 50 HIV-1 RNA copies/mL within the first year of treatment despite good adherence. Genomic DNA was extracted from peripheral blood lymphocytes (PBL) and amplified by polymerase chain reaction (PCR).

RESULTS

Successful treatment was associated with heterozygosity for the CCR5-Delta32-bp variant found in 24 of 184 responders (13%) vs. one of 72 nonresponders (1.4%; P=0.004). Eighty-four of 184 responders (45.7%) vs. 25 of 72 nonresponders (34.7%) were heterozygous for the SDF1-3'A allele (P=0.073). The CCR2-64I polymorphism was rare in both groups: 4.9% in responders vs. 1.4% in nonresponders (P=0.175). The odds ratio for successful treatment was 4.7 for individuals who tested positive for at least one variant allele of the three polymorphisms. Comparison of genotype frequencies between HIV-infected and healthy individuals showed highly significant differences (P<0.001).

CONCLUSIONS

Chemokine receptor polymorphisms have a modifying effect on the virological response to HAART. Multivariate analysis demonstrated that heterozygosity for the CCR5-Delta32-bp variant is an independent prognostic factor for treatment outcome.

CCR2 and CCR5 genotypes in HIV type 1-infected adolescents: limited contributions to variability in plasma HIV type 1 RNA concentration in the absence of antiretroviral therapy

In HIV-1-infected individuals, plasma viral RNA concentration as well as preservation of CD8+ naive T cells can vary by age. Host genetic factors previously shown to mediate HIV-1 pathogenesis in adults and children may operate differently in HIV-1-infected adolescents. Our PCR-based haplotyping of genetic variants at the loci encoding CC (beta) chemokine receptor 2 (CCR2) and CCR5 revealed nine haplotypes (designated A through G*2) in 179 seronegative and 228 seropositive adolescent participants from the Reaching for Excellence in Adolescent Care and Health (REACH) Study of the Adolescent Medicine and HIV/AIDS Research Network. The influence of CCR2-CCR5 haplotypes and genotypes on plasma HIV-1 RNA level was assessed in 207 AIDS-free seropositive individuals (mostly African-American females) who either did not receive therapy or had discontinued therapy for 6-12 months during initial follow-up between 1996 and 1999. The CCR2-64I-coding haplotype F*2 and the infrequent CCR5 Delta32-bearing haplotype G*2 had negligible impact on HIV-1 RNA level (p > 0.83) and CD4+ T cell counts (p > 0.30). In contrast, nine carriers of the E/E genotype had significantly higher (p = 0.007) plasma HIV-1 RNA level and slightly reduced CD4+ cell counts (p = 0.15) compared with those not carrying E/E or F*2 or G*2. The effect of E/E on HIV-1 RNA was stronger (p < 0.001) in a multivariable model adjusted for F*2 or G*2 (p = 0.45), race (p = 0.23), gender (p = 0.002), age (p = 0.26), and history of antiretroviral therapy (p < 0.001). Thus, among the major CCR2-CCR5 haplotypes/genotypes in chronically infected and predominantly African-American adolescents, only the E/E genotype appeared to influence early host-virus equilibration.

Distribution of chemokine receptor CCR2 and CCR5 genotypes and their relative contribution to human immunodeficiency virus type 1 (HIV-1) seroconversion, early HIV-1 RNA concentration in plasma, and later disease progression

At the CC (beta) chemokine receptor 2 (CCR2) and CCR5 loci, combinations of common single-nucleotide polymorphisms (SNPs) and a 32-bp deletion (Delta32) form nine stable haplotypes (designated A through G*2). The distribution of these CCR2-CCR5 haplotypes was examined among 703 participants in the Multicenter AIDS Cohort Study (MACS), the District of Columbia Gay (DCG) Study, and the San Francisco Men's Health Study (SFMHS). Highly exposed and persistently seronegative (HEPS; n = 90) Caucasian men from MACS more frequently carried heterozygous G*2 (Delta32) genotypes (especially A/G*2) and less frequently carried the homozygous E/E genotype compared with 469 Caucasian seroconverters (SCs) from the same cohort (P = 0.004 to 0.042). Among 341 MACS Caucasian SCs with 6- to 12-month human immunodeficiency virus type 1 (HIV-1) seroconversion intervals and no potent antiretroviral therapy, mean plasma HIV-1 RNA level during the initial 42 months after seroconversion was higher in carriers of the E/E genotype and lower in those with the 64I-bearing haplotype F*2 or the Delta32-bearing haplotype G*2 (and especially genotypes A/G*2 and F*2/G*2). A multivariable model containing these CCR markers showed significant composite effects on HIV-1 RNA at each of four postconversion intervals (P = 0.0004 to 0.050). In other models using time to AIDS as the endpoint, the same markers showed more modest contributions (P = 0.08 to 0.24) to differential outcome during 11.5 years of follow-up. Broadly consistent findings in the larger MACS Caucasian SCs and the smaller groups of MACS African-American SCs and the DCG and SFMHS Caucasian SCs indicate that specific CCR2-CCR5 haplotypes or genotypes mediate initial acquisition of HIV-1 infection, early host-virus equilibration, and subsequent pathogenesis.

Lack of effect of chemokine receptor CCR2b gene polymorphism (64I) on HIV-1 plasma RNA viral load and immune activation among HIV-1 seropositive female workers in Abidjan, Côte d'Ivoire

The prevalence of the CCR2b-V64I mutation among human immunodeficiency virus (HIV)-seropositive and -seronegative female workers and the potential effect of heterozygosity of this mutation on HIV-1 plasma RNA viral load and markers of immune activation were assessed. CCR2b-V64I was detected by polymerase chain reaction, followed by restriction enzymes analysis; plasma viral load was measured by the Amplicor HIV-1 monitor assay and CD4(+) T-cell counts and markers of immune activation by standard three-color FACscan flow cytometry. Of the 260 female workers, 56 (21.5%) were heterozygous for CCR2b-V64I, and 8 (3%) were homozygous. Of the 99 HIV-seronegative female workers, 19 (19.2%) were heterozygous for the CCR2b-V64I mutation compared with 37 (23%) of the 161 HIV-seropositive FSW (P = 0.47). In a univariate analysis of viral load among HIV-seropositive FSW, no difference was noted between those heterozygous for or without the mutation; both groups had plasma viral loads of 5.0 log(10) copies/ml. After controlling for the effects of CD4(+) T-cell counts in a multivariate analysis, no significant difference was observed between the groups in viral load or in markers of immune activation. The data suggest that the presence of the CCR2b mutation has no effect on HIV-1 plasma viral load and markers of immune activation in our study population. The finding that the frequency of this mutation is similar in HIV-seropositive and -seronegative female workers suggests that its presence is not associated with increased risk of HIV infection.

Frequency of CCR5 gene 32-basepair deletion in Chilean HIV-1 infected and non-infected individuals

A 32-basepair deletion polymorphism in the CCR5 chemokine receptor gene (CCR5Delta32) has been identified and shown to have functional significance in determining susceptibility to infection by human immunodeficiency virus type 1 (HIV-1) and possibly in influencing disease progression in HIV-1 positive individuals. These findings led to an interest in studies of DeltaCCR5 allele geographical distribution in human population, for complete understanding of the role of CCR5 in HIV-1 epidemiology. Inter-population variation in CCR5Delta32 frequency may be a significant factor in the prediction of AIDS endemicity. In this report we assessed the frequency of DeltaCCR5 in a Chilean population (63 HIV-1 infected and 62 non-infected individuals). No homozygous CCR5Delta32 individual was identified, and no significant difference was observed between HIV-1 infected (3/63) and non-infected (3/62) individuals for the heterozygote CCR5Delta32 state. This is the first evidence of the contribution of DeltaCCR5 allele to the genetic background of the Chilean population, which is characterized by intense ethnic admixture and by gene flow from the European Spanish gene pool.

Allelic distribution of CCR5 and CCR2 genes in an Italian population sample

Genetic polymorphisms of CCR5 and CCR2 human chemokine receptors have been associated with resistance during HIV-1 infection and disease progression. The protective effect of mutant alleles at these loci has important implications in AIDS pathogenesis. Chemokine receptors have a role in viral entry into target cells as well as in immune response modulation. In the present report, we studied the frequency of CCR5delta32 and CCR264I allelic variants among a representative sample of the Italian population. Observed allelic frequencies were 0.0454 and 0.0655, respectively. In both cases, genotype distribution was in equilibrium as predicted by the Hardy-Weinberg equation. Taken as a whole, about 21% of the population sample was found to be heterozygous for one or another of those two mutated alleles. Distribution of CCR5delta32 and CCR264I allelic variants within a population can be considered as a measure of genetic susceptibility to HIV infection and disease progression.

CCR2B-64I chemokine receptor allele and mother-to-child HIV-1 transmission or disease progression in children. French pediatric HIV infection study group

The beneficial role of a variant of the chemokine receptor CCR2B (CCR2B-641) in the evolution of HIV-1 infection in adults is still controversial. Furthermore, no studies have been performed in HIV-1-infected children. A multicenter and prospective study of 745 infants born to HIV-1-seropositive mothers was performed. The CCR2B-641 allele was studied in 525 non-African children among whom 523 had been previously genotyped for the CCR5delta32 allele and 220 African children. Of the 745 total, 376 children were infected and 369 were uninfected. In the complete population studied, the children homozygous for the CCR2B-64I allele and the heterozygous children were found distributed equally in the infected (respectively, 1.6% and 21%) and uninfected (respectively, 1.9% and 26.3%) groups (p < .22). Among 376 infected children, the incidence of stage C symptoms (U.S. Centers for Disease Control and Prevention [CDC] classification) or the progression of severe immune deficiency (CD4 <15%, CDC stage 3) was not significantly different in heterozygous infected children or children homozygous for the normal allele (p < .17 and p < .75, respectively). The same lack of protective effect was obtained when a separate analysis was performed in the non-African and African HIV-1-infected children.

Effects of plasma HIV RNA, CD4+ T lymphocytes, and the chemokine receptors CCR5 and CCR2b on HIV disease progression in hemophiliacs. Hemophilia Growth and Development Study

We have investigated the effects of plasma HIV RNA, CD4+ T lymphocytes and chemokine receptors CCR5 and CCR2b on HIV disease progression in hemophiliacs. We prospectively observed during follow-up 207 HIV-infected hemophiliacs in the Hemophilia Growth and Development Study. Plasma HIV RNA was measured on cryopreserved plasma from enrollment using the Chiron Corporation bDNA (version 2.0) assay. Genoytpe variants CCR2b-641 and CCR5-delta32 were detected using standard molecular techniques. Those with the mutant allele for CCR2b, and to a lesser extent CCR5, had lower plasma HIV RNA, and higher CD4+ T lymphocytes than did those without these genetic variants. After controlling for the effects of plasma HIV RNA and CD4+ T lymphocytes, those with the CCR2b mutant allele compared with those wild-type, had a trend toward a lower risk of progression to AIDS, adjusted relative hazard of 1.94 (95% confidence interval [CI], 0.9-4.18; p = .092), and AIDS-related death, relative hazard 1.97 (95% CI, 0.98-4.00; p = .059). We conclude that plasma HIV RNA, CD4+ T lymphocytes, and CCR genotypes are correlated, and the protective affect of CCR2b against HIV disease progression is not completely explained by plasma HIV RNA or CD4+ T-lymphocyte number.

Host genetic influences on HIV-1 pathogenesis

Cellular entry of HIV-1 is mediated by interaction with CD4 and chemokine receptors that serve as entry coreceptors. The immune response against HIV-1 is regulated by genes of the HLA locus. Genetic polymorphisms in these genes have recently been associated with effects on HIV-1 pathogenesis. The history and implications of these discoveries are described in this review.

Chemokine receptors as HIV-1 coreceptors: roles in viral entry, tropism, and disease

In addition to CD4, the human immunodeficiency virus (HIV) requires a coreceptor for entry into target cells. The chemokine receptors CXCR4 and CCR5, members of the G protein-coupled receptor superfamily, have been identified as the principal coreceptors for T cell line-tropic and macrophage-tropic HIV-1 isolates, respectively. The updated coreceptor repertoire includes numerous members, mostly chemokine receptors and related orphans. These discoveries provide a new framework for understanding critical features of the basic biology of HIV-1, including the selective tropism of individual viral variants for different CD4+ target cells and the membrane fusion mechanism governing virus entry. The coreceptors also provide molecular perspectives on central puzzles of HIV-1 disease, including the selective transmission of macrophage-tropic variants, the appearance of T cell line-tropic variants in many infected persons during progression to AIDS, and differing susceptibilities of individuals to infection and disease progression. Genetic findings have yielded major insights into the in vivo roles of individual coreceptors and their ligands; of particular importance is the discovery of an inactivating mutation in the CCR5 gene which, in homozygous form, confers strong resistance to HIV-1 infection. Beyond providing new perspectives on fundamental aspects of HIV-1 transmission and pathogenesis, the coreceptors suggest new avenues for developing novel therapeutic and preventative strategies to combat the AIDS epidemic.

Chemokine receptors and their crucial role in human immunodeficiency virus infection: major breakthroughs in HIV research

Within the last three years, major progress in the understanding of acquired immune deficiency syndrome pathogenesis has been achieved. The discovery that human immunodeficiency virus (HIV), in addition to the CD4 receptor, requires the presence of a coreceptor in order to infect cells has led to a series of breakthroughs in HIV research and knowledge. These include an increased understanding of viral entry, a connection of viral phenotype to specific coreceptor use, and an unequivocal linkage of a single human gene to host susceptibility. All in all these achievements provide a number of promising new strategies for combating HIV.