Association between CCR5 genotype and the clinical course of HIV-1 infection.

BACKGROUND: Heterozygosity for a 32-nucleotide deletion in the C-C chemokine receptor 5 gene (CCR5 delta 32) is associated with delayed disease progression in persons infected with HIV-1. OBJECTIVE: To compare the predictive value of CCR5 genotype with that of established markers in the clinical course of HIV-1 infection. DESIGN: Retrospective longitudinal study and nested case-control study. The latter included only long-term survivors, who were individually matched with progressors. SETTING: Amsterdam, the Netherlands. PARTICIPANTS: 364 homosexual men with HIV-1 infection. MEASUREMENTS: Polymerase chain reaction was used for CCR5 genotyping. Univariate and multivariate Cox proportional hazard analyses were done for disease progression with CCR5 genotype, CD4+ T-lymphocyte counts, T-lymphocyte function, HIV-1 biological phenotype (syncytium-inducing or non-syncytium-inducing HIV-1), and viral RNA load in serum as covariates. RESULTS: In the case-control study, 48% of long-term survivors were heterozygous for CCR5 delta 32 compared with 9% of progressors (odds ratio, 6.9 [95% CI, 1.9 to 24.8]). In the total study sample, CCR5 delta 32 heterozygotes had significantly delayed disease progression (P < 0.001; relative hazard, 0.4 [CI, 0.3 to 0.6]), a 1.5-fold slower decrease in CD4+ T-lymphocyte count (P = 0.01), and a 2.6-fold lower viral RNA load (P = 0.01) at approximately 2.3 years after seroconversion compared with CCR5 wild-type homozygotes. At the end of the study, both groups showed the same prevalence of syncytium-inducing HIV-1, but CCR5 delta 32 heterozygotes had a delayed conversion rate. The protective effect of CCR5 delta 32 heterozygosity was stronger in the presence of only non-syncytium-inducing HIV-1. The CCR5 genotype predicted disease progression independent of viral RNA load, CD4+ T-lymphocyte counts, T-lymphocyte function, and HIV-1 biological phenotype. CONCLUSIONS: The addition of CCR5 genotype to currently available laboratory markers may allow better estimation of the clinical course of HIV-1 infection.

Temporal relationship between elongation of the HIV type 1 glycoprotein 120 V2 domain and the conversion toward a syncytium-inducing phenotype.

The second and third variable domains (V2 and V3) of the human immunodeficiency virus type 1 (HIV-1) gp120 envelope molecule have been shown to be determinants of syncytium-inducing (SI) capacity. Previously we have reported evidence that increased length of the V2 domain and duplication or relocation of potential N-linked glycosylation sites in V2 might be used as prognostic markers for evolution toward an SI phenotype. Here, we used a PCR assay that discriminates a 6-nucleotide difference in the length of the V2 domain, with a sensitivity of 1 elongated V2 domain when present in a background of 125 to 625 short V2 domains. Analysis of DNA isolated directly from PBMCs from 11 HIV-1-infected individuals prior to SI phenotype conversion revealed, however, that the usefulness of this PCR for V2 length polymorphism as predictive marker for SI phenotype evolution is limited. The strong association as observed in our previous study between elongation of the V2 domain and an SI phenotype prompted us to expand our first analysis. An extremely significant correlation was observed between V2 length and virus phenotype for samples obtained at about the moment of SI conversion, but not for samples obtained 3 to 35 months after SI phenotype conversion, suggesting that changes in V2 may be only transiently required to allow SI phenotype evolution. This possibly only transient nature of V2 elongation may explain the discrepancy between results by our group and others.

Simple determination of human immunodeficiency virus type 1 syncytium-inducing V3 genotype by PCR.

Human immunodeficiency virus type 1 (HIV-1) phenotype variability plays an important role in the pathogenesis of AIDS. The presence of syncytium-inducing (SI) HIV-1 isolates in infected individuals is associated with a rapid decline of CD4+ T cells, rapid disease progression, and reduced survival time after AIDS diagnosis. The strong association between the SI capacity of HIV-1 and the presence of positively charged amino acid residues at positions 306 and/or 320 in the third variable domain (V3) of gp120 could here be confirmed in 97% of 402 primary HIV-1 isolates, indicating that the V3 genotype may be useful for prediction of the viral phenotype. The V3 DNA sequences revealed a remarkably limited codon usage for the amino acid residues that are responsible for virus phenotype. On the basis of this limited SI-specific DNA sequence variation, four SI-specific oligonucleotides were designed for selective amplification of V3 from SI but not non-SI HIV-1 isolates. This PCR analysis allowed the prediction of the biological phenotype of HIV-1 isolates on the basis of the V3 genotype and may prove to be useful for monitoring SI capacity of HIV-1 isolates in infected individuals.

Reduction of HTLV-I-infected cells in blood by leukocyte filtration.

Leukocyte filtration was performed with HTLV-I-infected blood and with blood supplemented with cultured HTLV-I-transformed cells. Reduction of infectivity upon leukocyte filtration was determined by the polymerase chain reaction (PCR) using primers indicative for the HTLV-I-pol and tax genes. Two different commercially available filters were used: a column-shaped cellulose acetate and a flat-bed polyester filter. Both filters yielded reduction of at least 3 10logs for cultured HTLV-I-infected cells. When blood from HTLV-I-infected individuals was used for filtration, the number of infected cells was reduced by 1-3 10logs. Although filtered blood as yet cannot be regarded as safe, it is concluded that leukocyte filtration of HTLV-I-infected blood potentially contributes to reducing the spread of HTLV-I by blood transfusion.