Divergent acute-phase viral kinetics in the CSF and plasma, and proportionally greater long-term decrements in CSF HIV-1 RNA in slow early-responders or poor overall plasma responders indicate variable compartmentalization of CSF infection, consistent with a model of two prototypes of CSF infection: short-lived, transitory infection that predominates in early HIV-1 infection and longer-lived, more autonomous CSF infection predominating in late HIV-1 infection. Additional studies will be needed to define more precisely the acute and longer-term CSF kinetics in different clinical settings and to assess this model.
The Celera Diagnostics ViroSeq HIV-1 Genotyping System is a Food and Drug Administration-cleared, integrated system for sequence-based analysis of drug resistance mutations in subtype B human immunodeficiency virus type 1 (HIV-1) protease and reverse transcriptase (RT). We evaluated the performance of this system for the analysis of diverse HIV-1 strains. Plasma samples were obtained from 126 individuals from Uganda, Cameroon, South Africa, Argentina, Brazil, and Thailand with viral loads ranging from 2.92 to >6.0 log 10 copies/ml. HIV-1 genotyping was performed with the ViroSeq system. HIV-1 subtyping was performed by using phylogenetic methods. PCR products suitable for sequencing were obtained for 125 (
Population screening has been proposed for Fragile X syndrome to identify premutation carrier females and affected newborns. We developed a PCR-based assay capable of quickly detecting the presence or absence of an expanded FMR1 allele with high sensitivity and specificity. This assay combines a triplet repeat primed PCR with high-throughput automated capillary electrophoresis. We evaluated assay performance using archived samples sent for Fragile X diagnostic testing representing a range of Fragile X CGG-repeat expansions. Two hundred five previously genotyped samples were tested with the new assay. Data were analyzed for the presence of a trinucleotide "ladder" extending beyond 55 repeats, which was set as a cut-off to identify expanded FMR1 alleles. We identified expanded FMR1 alleles in 132 samples (59 premutation, 71 full mutation, 2 mosaics) and normal FMR1 alleles in 73 samples. We found 100% concordance with previous results from PCR and Southern blot analyses. In addition, we show feasibility of using this assay with DNA extracted from dried-blood spots. Using a single PCR combined with high-throughput fragment analysis on the automated capillary electrophoresis instrument, we developed a rapid and reproducible PCR-based laboratory assay that meets many of the requirements for a first-tier test for population screening.
The US Food and Drug Administration-cleared ViroSeq HIV-1 Genotyping System (ViroSeq) and other population sequencing-based human immunodeficiency virus type 1 (HIV-1) genotyping methods detect antiretroviral drug resistance mutations present in the major viral population of a test sample. These assays also detect some mutations in viral variants that are present as mixtures. We compared detection of the K103N nevirapine resistance mutation using The US Food and Drug Administration-cleared ViroSeq HIV-1 Genotyping System (ViroSeq) and other population sequencing-based genotyping methods detect mutations present in the major viral population in a test sample. These assays also detect some mutations that are present at lower levels. Using recombinant viral stocks, we previously demonstrated that ViroSeq reliably detects drug resistance mutations present in 40% of the viral population in samples with viral loads from 2000 to 5000 copies/ml 1 , lower level mixtures were not evaluated in that study. In another study, ViroSeq detected the K103N mutation in a recombinant human immunodeficiency virus type 1 (HIV-1) strain at a level of 10%. 2HIV-1 variants with the K103N mutation are often selected in women who receive a single dose of the antiretroviral drug nevirapine for prevention of HIV-1 motherto-child transmission. 3,4 We evaluated the sensitivity of ViroSeq for detection of K103N in 305 clinical plasma samples collected from African women 6 to 8 weeks after single dose nevirapine administration. Samples were collected from women in the HIV Network for Prevention Trial (HIVNET) 012 trial 5,6 (Ugandan women, 146 subtype A samples and 95 subtype D samples) and the Nevirapine-
Background Interpreting human immunodeficienc virus type 1 (HIV-1) genotypic drug-resistance test results is challenging for clinicians treating HIV-1–infected patients. Multiple drug-resistance interpretation algorithms have been developed, but their predictive value has rarely been evaluated using contemporary clinical data sets. Methods We examined the predictive value of 4 algorithms at predicting virologic response (VR) during 734 treatment-change episodes (TCEs). VR was define as attaining plasma HIV-1 RNA levels below the limit of quantification Drug-specifi genotypic susceptibility scores (GSSs) were calculated by applying each algorithm to the baseline genotype. Weighted GSSs were calculated by multiplying drug-specifi GSSs by antiretroviral (ARV) potency factors. Regimen-specifi GSSs (rGSSs) were calculated by adding unweighted or weighted drug-specif c GSSs for each salvage therapy ARV. The predictive value of rGSSs were estimated by use of multivariate logistic regression. Results Of 734 TCEs, 475 (65%) were associated with VR. The rGSSs for the 4 algorithms were the variables most strongly predictive of VR. The adjusted rGSS odds ratios ranged from 1.6 to 2.2 (P < .001). Using 10-fold cross-validation, the averaged area under the receiver operating characteristic curve for all algorithms increased from 0.76 with unweighted rGSSs to 0.80 with weighted rGSSs. Conclusions Unweighted and weighted rGSSs of 4 genotypic resistance algorithms were the strongest independent predictors of VR. Optimizing ARV weighting may further improve VR predictions.
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