Assessment of HIV Screening Tests for Use in Preexposure Prophylaxis Programs.

Preexposure prophylaxis programs involve frequent human immunodeficiency virus (HIV) testing. We evaluated the sensitivity of 2 antigen/antibody immunoassays (Architect and Bioplex), 2 antibody-based rapid tests (Vikia-HIV-1/2 and Autotest-VIH), and 1 antigen/antibody rapid test (Alere HIV Combo) for the diagnosis of HIV infection. Among the 31 HIV-1-infected participants in the ANRS-IPERGAY trial, HIV-1 RNA was detected alone in only 2. The sensitivities of the Architect and Bioplex assays were 83% (95% confidence interval [CI], 76%-99%) and 82% (95% CI, 63%-94%), respectively. The sensitivities of the Vikia, Autotest, and Alere tests were 54% (95% CI, 34%-72%), 50% (95% CI, 31%-69%), and 78% (95% CI, 58%-91%), respectively. Antigen/antibody tests should be preferred to avoid missing cases of acute HIV infection and to decrease the related risks of viral transmission and emergence of drug resistance.

Evaluation of HIV antigen/antibody combination ELISAs for diagnosis of HIV infection in Dar Es Salaam, Tanzania.

INTRODUCTION: The aim of this study was to evaluate the performance of Enzygnost HIV Integral II antigen/antibody combination ELISAs in order to formulate HIV ELISA testing algorithms for the Ministry of Health and Social Welfare, Tanzania. METHODS: This was a laboratory-based evaluation of Enzygnost HIV Integral II Antibody/ Antigen, Murex HIV antigen/antibody and Vironostika HIV Uniform II antigen/antibody conducted between October 2011 and May 2012. RESULTS: A total of 600 blood samples were included in the evaluation. A total of 209/596 (35.1%) serum samples were confirmed HIV positive. Of these, the prevalence of HIV infection was 2.3% (3/130), 2.3% (3/127), 2.2% (3/139) and 100% (200/200) for VCT clients, ANC attendees, blood donors and CTC patients, respectively. Three hundred and eighty seven (64.9%) were HIV negative samples. Sensitivity was 100% (95% CI; 98.3-100%) for all the three HIV ELISAs. The specificity for the Enzygnost HIV Integral II and Murex was 100% (95% CI; 99.1-100%). The final specificity at repeat testing was 99.5% (95% CI; 98.2-99.9%) for Vironostika. Enzygnost HIV Integral II detected HIV infection seven days since first bleed. CONCLUSION: Initial testing using either Vironostika or Murex HIV antigen/antibody combination ELISA followed by testing of reactive samples on the Enzygnost HIV Integral II gave a sensitivity and specificity of 100% with reduced window period. Combination of two HIV antigen/antibody combination ELISAs can be used as an alternative confirmatory testing strategy for screening of donated blood at the National and Zonal blood transfusion centres and in lab diagnosis of HIV infection.

Cost savings associated with testing of antibodies, antigens, and nucleic acids for diagnosis of acute HIV infection.

Efforts to identify all persons infected with HIV in the United States are driven by the hope that early diagnosis will lower risk behaviors and decrease HIV transmission. Identification of HIV-infected people earlier in the course of their infection with HIV antigen/antibody (Ag/Ab) combination assays (4th-generation HIV assays) should help achieve this goal. We compared HIV RNA nucleic acid test (NAT) results to the results of a 4th-generation Ag/Ab assay (Architect HIV Ag/Ab Combo [HIV Combo] assay; Abbott Diagnostics) in 2,744 HIV antibody-negative samples. Fourteen people with acute HIV infection (HIV antibody negative/NAT positive) were identified; the HIV Combo assay detected nine of these individuals and was falsely negative in the remaining five. All five persons missed by the HIV Combo assay were in the stage of exponential increase in plasma virus associated with acute HIV infection (3, 7, 20, 35, 48). In contrast, most acutely infected persons detected by the HIV Combo assay demonstrated either a plateauing or decreasing plasma viral load. The HIV Combo assay also classified as positive five other samples which were negative by NAT. Taken together, the HIV Combo assay had a sensitivity of 73.7% and a specificity of 99.8%. Using published data, we estimated secondary transmission events had HIV infection in these five individuals remained undiagnosed. Screening of our population with NAT cost more than screening with the HIV Combo assay but achieved new diagnoses that we predict resulted in health care savings that far exceed screening costs. These findings support the use of more sensitive assays, like NAT, in HIV screening of populations with a high prevalence of acute HIV infection.

Ultrasensitive quantitative HIV-1 p24 antigen assay adapted to dried plasma spots to improve treatment monitoring in low-resource settings.

BACKGROUND: Our group has previously developed a quantitative and ultrasensitive HIV-1 p24 antigen assay that is inexpensive, easy-to-perform, and can be carried out in low-resource settings. Since antiretroviral therapies are becoming more accessible in resource-constrained countries, methods to assess HIV-1 viraemia are urgently needed to achieve a high standard of care in HIV-1 management. OBJECTIVES: To adapt our quantitative assay to dried plasma spots (DPS), in order to further simplify this test and make it more accessible to resource-constrained countries. STUDY DESIGN: DPS from 47 HIV-seropositive, treated or untreated adult individuals and 30 healthy individuals were examined. RESULTS: A specificity of 100% was observed when p24 antigen was measured using DPS, and no differences of p24 concentration could be seen between DPS and venous plasma. The correlation between DPS and venous plasma p24 was excellent (R=0.93, CI(95%)=0.88-0.96, p<0.0001). Similarly, p24 antigen concentrations using DPS were well correlated with RNA viral load (R=0.53, CI(95%)=0.27-0.72, p=0.0002). CONCLUSIONS: This quantitative p24 antigen test has similar sensitivity and specificity using DPS and venous plasma, and has the potential to improve health care delivery to HIV-affected individuals in resource-constrained countries.

Mother-to-child HIV-1 transmission: quantitative assessment of viral burden as a diagnostic tool and prognostic parameter in HIV-1-infected children.

Polymerase chain reaction was performed in 251 infants born to HIV-1-seropositive mothers to diagnose HIV-1 infection. Assay specificity was invariably > 95%, regardless of age at testing, while sensitivity ranged from 15% in neonates (within 48 h of birth) to > 95% in infants over 1 month of age. Evaluation of viral burden in 43 infected infants by means of quantitative DNA-PCR disclosed that the number of HIV-1 proviruses ranged from 5 to 947 per 100,000 peripheral blood mononuclear cells. Clinical follow-up demonstrated that a high viral burden was associated significantly with disease onset.