In vivo and in vitro analysis of chloroquine resistance in Plasmodium falciparum isolates from Senegal

To determine the predictive value of chloroquine (CQ) resistance markers in Senegal, Plasmodium falciparum DNA polymorphisms in pfmdr1and pfcrt were examined in relation to clinical outcome. Despite CQ treatment, 17% of patients had parasitemia after 28 days. Examination of molecular markers of CQ resistance revealed that 64% of all isolates had the T76 resistant allele at the pfcrt locus, while 30% carried the Y86 resistant allele at the pfmdr1 locus. The pfcrt T76 allele was present not only in all in vivo resistant isolates, 89% of in vitro resistant isolates, but also in 35% of in vitro sensitive isolates. The pfmdr1 N86Y polymorphism did not correlate with in vitro or in vivo CQ resistance. Our data suggest that the pfcrt T76 allele alone is required but not a sufficient predictor for in vivo CQ resistance.     

Associations between MHC class I and susceptibility to HIV-2 disease progression

OBJECTIVES: Human immunodeficiency virus type 2 (HIV-2) progression to disease is significantly slower than that of human immunodeficiency virus type 1 (HIV-1). Genetic determinants for susceptibility to disease progression were hypothesized to play a more significant role in this infection compared with HIV-1. We sought to identify common human lymphocyte antigen (HLA) alleles in the Senegalese population and to compare HLA profiles between HIV-2-infected individuals with low and high risk for disease progression. STUDY DESIGN/METHODS: We conducted a case-control study investigating possible associations between MHC class I genes and the risk of disease progression in HIV-2-infected individuals. The MHC class I genotype was molecularly defined using polymerase chain reaction with sequence specific primers (PCR-SSP) in 62 female sex workers from the Dakar, Senegal cohort. Lack of antibodies to the HIV-2 antigen p26 has been previously shown to predict disease progression and was used in this study as a surrogate marker. Twenty-one cases were identified lacking antibodies to p26, therefore at a higher risk of disease progression, and were compared with 41 p26 antibody-positive, randomly selected controls. RESULTS: Statistical analysis showed that HLA B35 was significantly associated with lack of p26 antibodies, and higher risk of disease progression ( < 0.05). The same association was found for the self-defined class I haplotypes B35-Cw4 and A23-Cw 7 ( < 0.05). The HLA B 53 allele was associated with slower disease progression; however, this association was not statistically significant. We observed a trend whereby heterozygotes were at lower risk for HIV-2 disease progression, as previously reported in HIV-1 disease. CONCLUSIONS: In this West African population, a distinct profile of HLA class I alleles was observed, and many of these appear to influence disease progression in HIV-2 infection.     

Absolute CD4 T-cell counting in resource-poor settings: direct volumetric measurements versus bead-based clinical flow cytometry instruments

Flow cytometry is an accurate but expensive method to determine absolute CD4 cell counts. We compared different methods to measure absolute CD4 counts in blood samples from HIV-infected and uninfected subjects using a research/clinical flow cytometer (FACScan); a dedicated clinical instrument (FACSCount); and a volumetric, mobile, open-system flow cytometer equipped with 3 fluorescence and 2 light scatter detectors (Cyflow SL blue). The FACScan and Cyflow were used as single-platform instruments, but they differ in running cost, which is a central factor for resource-poor settings. Direct volumetric and bead-based CD4 measurements on the Cyflow were compared with 2 bead-based single-platform CD4 measurements on the FACSCount and on FACScan (TruCount) in "Le Dantec" Hospital, Dakar, Senegal, using whole blood samples from 102 HIV+ and 28 HIV- subjects. The agreement between the various measurement methods was evaluated by Bland-Altman analysis. Volumetric CD4 measurements on the Cyflow using a no-lyse-no-wash (NLNW) procedure and a lyse-no-wash (LNW) procedure correlated well with each other (R2 = 0.98) and with CD4 measurements on the FACSCount (R2 = 0.97) and FACScan (R2 = 0.97), respectively. Red blood cell lysis had no negative effect on the accuracy of absolute CD4 counting on the Cyflow. An excellent correlation was observed between bead-based CD4 measurements on the Cyflow and CD4 measurements on the FACSCount (R2 = 0.99) and FACScan (R2 = 0.99). Rigid internal and external quality control monitoring and adequate training of technicians were considered essential to generate accurate volumetric CD4 measurements on the Cyflow.     

No difference in clinical progression between patients infected with the predominant human immunodeficiency virus type 1 circulating recombinant form (CRF) 02_AG strain and patients not infected with CRF02_AG,in Western and West-Central Africa: a four-year prospective multicenter study

To compare human immunodeficiency virus (HIV) type 1 disease progression in patients infected by the predominant strain circulating recombinant form (CRF) 02_AG in western and west-central Africa and in patients infected by other strains, a prospective multicenter cohort study was conducted in Cameroon and Senegal. Among the 335 patients, a broad HIV-1 group M subtype diversity was observed in the envelope V3-V5 region, but strain CRF02_AG predominated in both Cameroon and Senegal (61.2% and 62.9%, respectively; P<.8). Multivariate analyses showed no difference between patients infected by CRF02 strains and those infected by other strains in terms of survival (adjusted hazards ratio [HR], 1.16; 95% confidence interval [CI], 0.76-1.78; P=.5), clinical disease progression (HR, 0.79; 95% CI, 0.50-1.25; P=.3), or square root CD4 cell decline (regression coefficient, -0.01; 95% CI, -0.82 to 0.81; P=.9). This study suggests that the predominance of HIV-1 CRF02_AG strain in western and west-central Africa should have no major clinical consequences.     

Efficacy, safety, and selection of molecular markers of drug resistance by two ACTs in Mali

We conducted a randomized single-blinded trial comparing the efficacy and safety of artesunate (AS) + amodiaquine (AQ, 3 days) versus AS (3 days) + sulfadoxine-pyrimethamine (SP, single dose) versus AS monotherapy (5 days) in Southern Mali. Uncomplicated malaria cases were followed for 28 days. Molecular markers of drug resistance were determined. After identification of recrudescences by genotyping, both artemisinin-based combination therapies (ACTs) reached nearly 100% efficacy at Day 14 and Day 28 versus 98.3% and 96.5% for AS, respectively (P > 0.05). AS + SP significantly selected DHFR and DHPS mutations associated with sulfadoxine and pyrimethamine resistance (P < 0.001), and AS + AQ equally selected PfCRT and PfMDR1 point mutations associated with chloroquine and AQ resistance (P < 0.001). No significant adverse event attributable to any of the study drugs was found. The ACTs were efficacious and safe, but the selection of markers for resistance to the partner drugs raises concerns over their lifespan in areas of intense malaria transmission.     

Positive association between beta-chemokine-producing T cells and HIV type 1 viral load in HIV-infected subjects in Abidjan, Côte d'Ivoire

The role of beta-chemokines in controlling HIV replication in vivo is still controversial. Therefore, the association between HIV-1 plasma viral load and the capacity of CD4(+) and CD8(+) T cells to produce beta-chemokines was studied in 28 antiretroviral drug-na?ve HIV-1-infected female sex workers in Abidjan, C?te d'Ivoire. Percentages of beta-chemokine-positive T cells were measured in peripheral blood mononuclear cells by flow cytometry after intracellular staining for RANTES (regulated on activation, normal T expressed and secreted), macrophage inflammatory protein (MIP)-1alpha, and MIP-1beta. HIV-1-infected subjects had higher percentages of MIP-1alpha- and MIP-1beta-positive CD4(+) and CD8(+) T cells (p < 0.02) and of RANTES-positive CD8(+) T cells (p = 0.054) than uninfected controls. Percentages of RANTES- and MIP-1beta-positive CD8(+) T cells correlated directly with HIV-1 plasma viral load (p < 0.02). Percentages of beta-chemokine-positive CD4(+) and CD8(+) T cells correlated directly with percentages of HLA-DR-positive T cells (p < 0.02) and inversely (except RANTES in CD4(+) T cells) with absolute numbers of CD4(+) T cells (p < 0.05) in peripheral blood. These data indicate that increased percentages of beta-chemokine-producing T cells in HIV-1-infected subjects correlate with disease progression and are a sign of viremia-driven chronic T cell activation.     

Cellular human immunodeficiency virus (HIV)-protective factors: a comparison of HIV-exposed seronegative female sex workers and female blood donors in Abidjan,Côte d'Ivoire

Cellular factors that may protect against human immunodeficiency virus (HIV) infection were investigated in 27 HIV-exposed seronegative (ESN) female sex workers (FSWs) and 27 HIV-seronegative female blood donors. Compared with blood donors, ESN FSWs had significantly decreased expression levels of C-X-C chemokine receptor 4 (CXCR4), but not of C-C chemokine receptor 5, on both memory (P<.001) and naive (P=.041) CD4(+) T cells. CXCR4 down-regulation was associated with prolonged duration of commercial sex work by ESN FSWs. CD38 expression on CD8(+) T cells was significantly increased among ESN FSWs, compared with that among blood donors (P=.017). There were no differences in HLA-DR and CD62L expression between blood donors and ESN FSWs. Proportions of T cells producing the beta-chemokines RANTES (regulated on activation, normally T cell-expressed and -secreted), macrophage inflammatory protein (MIP)-1alpha, and MIP-1beta or the cytokines interleukin (IL)-2, IL-4, interferon-gamma, and tumor necrosis factor-alpha, were similar in the 2 groups. These data indicate that ESN FSWs differ from HIV-seronegative female blood donors with respect to immunological factors that have no clear protective potential against HIV transmission.