RESUMO
BACKGROUND: In resource-limited settings, viral load monitoring of HIV-infected patients receiving antiretroviral therapy (ART) is not readily available because of high costs. Here, we compared the accuracy and costs of quantitative and qualitative pooled methods with standard viral load testing. METHODS: Blood was collected prospectively from 461 patients receiving first-line ART in Mozambique who had not been evaluated previously with viral load testing. Screening for virologic failure of ART was performed quantitatively (ie, standard viral loads) and qualitatively [one and 2 rounds of polymerase chain reaction (PCR)]. Individual samples and minipools of 5 samples were then analyzed using both methods. The relative efficiency, accuracy, and costs of each method were calculated based on viral load thresholds for ART failure. RESULTS: Standard viral load testing of individual samples revealed a high rate of ART failure (19%-23%) across all virologic failure thresholds, and the majority of the patients (93%) with viral loads >1500 copies per milliliter had genotypic resistance to drugs in their ART regimen. Pooled quantitative screening and deconvolution testing had positive and negative predictive values exceeding 95% with cost savings of $11,250 compared with quantitative testing of each sample individually. Pooled qualitative screening and deconvolution testing had a higher cost savings of $30,147 for 1 PCR round and $25,535 for 2 PCR rounds compared with quantitative testing each sample individually. Both pooled qualitative PCR methods had positive and negative predictive values ≥90%, but the pooled 1-round PCR method had a sensitivity of 64%. CONCLUSIONS: Given the high rate of undiagnosed ART failure and drug resistance in this cohort, it is clear that virologic monitoring is urgently needed in this population. Here, we compared alternative methods of virologic monitoring with standard viral load testing of individual samples and found these methods to be cost saving and accurate. The test characteristics of each method will likely need to be considered for each local population before it is adopted.
Assuntos
Fármacos Anti-HIV/uso terapêutico , Infecções por HIV/tratamento farmacológico , Reação em Cadeia da Polimerase/métodos , RNA Viral/isolamento & purificação , Infecções por HIV/sangue , Infecções por HIV/epidemiologia , Infecções por HIV/virologia , Humanos , Moçambique/epidemiologia , Falha de Tratamento , Carga ViralRESUMO
Genetic elements in HIV-1 subtype B tat and env are associated with neurotoxicity yet less is known about other subtypes. HIV-1 subtype C tat and env sequences were analyzed to determine viral genetic elements associated with neurocognitive impairment in a large Indian cohort. Population-based sequences of HIV-1 tat (exon 1) and env (C2-V3 coding region) were generated from blood plasma of HIV-infected patients in Pune, India. Participants were classified as cognitively normal or impaired based on neuropsychological assessment. Tests for signature residues, positive and negative selection, entropy, and ambiguous bases were performed using tools available through Los Alamos National Laboratory (http://www.hiv.lanl.gov) and Datamonkey (http://www.datamonkey.org). HIV-1 subtype C tat and env sequences were analyzed for 155 and 160 participants, of which 34-36% were impaired. Two signature residues were unique to impaired participants in exon 1 of tat at codons 29 (arginine) and 68 (proline). Positive selection was noted at codon 29 among normal participants and at codon 68 in both groups. The signature at codon 29 was also a signature for low CD4+ (<200 cells/mm(3)) counts but remained associated with impairment after exclusion of those with low CD4+ counts. No unique genetic signatures were noted in env. In conclusion, two signature residues were identified in exon 1 of HIV-1 subtype C tat that were associated with neurocognitive impairment in India and not completely accounted for by HIV disease progression. These signatures support a linkage between diversifying selection in HIV-1 subtype C tat and neurocognitive impairment.
Assuntos
Complexo AIDS Demência/epidemiologia , Complexo AIDS Demência/virologia , Infecções por HIV/complicações , Infecções por HIV/virologia , HIV-1/genética , Produtos do Gene env do Vírus da Imunodeficiência Humana/genética , Produtos do Gene tat do Vírus da Imunodeficiência Humana/genética , Adulto , Códon , Estudos de Coortes , Feminino , Frequência do Gene , Genótipo , HIV-1/isolamento & purificação , Humanos , Índia , Masculino , Análise de Sequência de DNARESUMO
BACKGROUND: To develop a low cost method to screen for virologic failure of antiretroviral therapy (ART) and HIV-1 drug resistance, we performed a retrospective evaluation of a screening assay using serial dilutions of HIV-1 RNA-spiked blood plasma and samples from patients receiving >6 months of first-line ART. METHODS: Serial dilution testing was used to assess sensitivity of a simple PCR-based assay (targeted at ≥1,000 HIV RNA copies/mL). We created blood plasma minipools of five samples, extracted HIV RNA from the pools, PCR amplified the reverse transcriptase (RT) coding region of the HIV-1 pol gene from extracted RNA, sequenced PCR product of positive pools, and used sequences to determine drug resistance. Sensitivity, specificity, and predictive values were determined for different levels of virologic failure based on maximum viral loads of individual samples within a pool. RESULTS: Of 295 samples analyzed, 43 (15%) had virologic failure at ≥50 copies/mL (range 50-10,500 copies/mL, four at ≥1,000 copies/mL). The assay demonstrated 100% sensitivity to detect virus from these four samples, requiring only one round of PCR, and 56% and 89% sensitivity to detect samples with ≥50 and ≥500 copies/mL using two rounds. Amplified PCR products of all positive pools were successfully sequenced and 30% harbored ≥1 major resistance mutation. This method would have cost 10% of the combined costs of individual viral load and resistance testing. CONCLUSIONS: We present a novel method that can screen for both virologic failure of first-line ART and drug resistance. The method is much less expensive than current methods, which may offer sustainability in resource-limited settings.
Assuntos
Fármacos Anti-HIV/uso terapêutico , Infecções por HIV/tratamento farmacológico , Adulto , Farmacorresistência Viral , Feminino , Infecções por HIV/diagnóstico , HIV-1/genética , HIV-1/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , RNA Viral/sangue , Estudos Retrospectivos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Falha de Tratamento , Carga Viral , Adulto Jovem , Produtos do Gene pol do Vírus da Imunodeficiência Humana/genéticaRESUMO
BACKGROUND: Similar to other resource-limited settings, cost restricts availability of viral load monitoring for most patients receiving antiretroviral therapy in Tijuana, Mexico. We evaluated if a pooling method could improve efficiency and reduce costs while maintaining accuracy. METHODS: We evaluated 700 patient blood plasma specimens at a reference laboratory in Tijuana for detectable viremia, individually and in 10 × 10 matrix pools. Thresholds for virologic failure were set at ≥500, ≥1000 and ≥1500 HIV RNA copies per milliliter. Detectable pools were deconvoluted using pre-set algorithms. Accuracy and efficiency of the pooling method were compared with individual testing. Quality assurance (QA) measures were evaluated after 1 matrix demonstrated low efficiency relative to individual testing. RESULTS: Twenty-two percent of the cohort had detectable HIV RNA (≥50 copies/mL). Pooling methods saved approximately one third of viral load assays over individual testing, while maintaining negative predictive values of >90% to detect samples with virologic failure (≥50 copies/mL). One matrix with low relative efficiency would have been detected earlier using the developed QA measures, but its exclusion would have only increased relative efficiency from 39% to 42%. These methods would have saved between $13,223 and $14,308 for monitoring this cohort. CONCLUSIONS: Despite limited clinical data, high prevalence of detectable viral loads and a contaminated matrix, pooling greatly improved efficiency of virologic monitoring while maintaining accuracy. By improving cost-effectiveness, these methods could provide sustainability of virologic monitoring in resource-limited settings, and incorporation of developed QA measures will most likely maximize pooling efficiency in future uses.