Diagnostic accuracy of HIV test kits, Genscreen Ultra and Bioelisa.

PURPOSE: Genetic diversities in different countries affect the performance of HIV test kits. Therefore, WHO recommends evaluation of every HIV test kit in countries' context before its use. Therefore, this study aimed to evaluate the performance of Genscreen ULTRA HIV Ag-Ab and Bioelisa. MATERIALS AND METHODS: The study had used 400 characterized plasma samples obtained from CDC Atlanta bio-bank derived from Africa, USA, and Thailand. RESULTS: Diagnostic performance of both test kits under evaluation was assessed at 95% CI. Genscreen ULTRA HIV Ag-Ab had sensitivity and negative predictive value of 99.5% [95% CI, 97.2-99.9] and the specificity and positive predictive value of 98.5% [95% CI, 95.7-99.7]. Bioelisa HIV test kit had exhibited sensitivity and negative predictive value of 99% [95% CI, 96.4-99.7] and specificity and positive predictive value of 98.5% [95% CI, 95.7-99.7]. Both test kits were able to detect almost all samples with HIV-2, dual infections, and seroconversion. CONCLUSION: Both the test kits were highly sensitive and specific in detecting HIV. However, there are still few samples containing HIV antibody which were not identified by both kits. Therefore, additional screening measures should be done in using these assays for blood transfusion and organ transplantation. In addition, the study can be used as a reference by other African countries.

Stable pattern of HIV-1 subtype C Gag-specific T-cell responses coincides with slow rate of CD4 T-cell decline in HIV-infected Ethiopians.

We studied HIV-1 clade C Gag-specific T-cell responses in five HIV-infected Ethiopians with a relatively slow (< 15 cells/microl per year) and five with a fast (> 45 cells/microl per year) CD4 T-cell decline longitudinally. Six study subjects had T-cell responses directed to one or more HIV-1 Gag peptides. The persistence of strong and broad anti-Gag cytotoxic T-lymphocyte responses was associated with a slow rate of CD4 T-cell decline and with human leukocyte antigen alleles from the B27 supertype.

Alternative approach to blood screening using the ExaVir reverse transcriptase activity assay.

408 non-selected samples were obtained from healthy, adult individuals donating blood at the Ethiopian Red Cross Society-National Blood Transfusion Service. All samples were screened for HIV using the Vironostika Ag/Ab test, the Amplicor DNA PCR and examined for the presence of HIV reverse transcriptase (RT) using the ExaVir Load test (version 2). A panel of supplementary tests was used to evaluate the HIV status of the discordant samples and to confirm positivity. One aim was to assess an RT based test for screening for HIV in comparison with other more conventional tests. An HIV-prevalence of 3.4 % (14/408) was found. The Vironostika Ag/Ab test produced 391 negative, and according to the supplementary testing, 14 true- and three false- positive test results. The corresponding figures for the Amplicor DNA PCR test was 384 negative, 14 true- and two extra probably false -positive samples. In addition, the DNA PCR generated eight indeterminate results. The colorimetric version of the ExaVir load test exhibited 100 % specificity and detected RT in 13 of the true positive samples, but failed to detect one sample containing 200 HIV RNA copies /mL. This sample was detectable in the fluorimetric version of the test. The detection of RT activity in addition to the currently used markers would seem to have a potential for use in blood screening.

Field expansion of DNA polymerase chain reaction for early infant diagnosis of HIV-1: The Ethiopian experience.

BACKGROUND: Early diagnosis of infants infected with HIV (EID) and early initiation of treatment significantly reduces the rate of disease progression and mortality. One of the challenges to identification of HIV-1-infected infants is availability and/or access to quality molecular laboratory facilities which perform molecular virologic assays suitable for accurate identification of the HIV status of infants. METHOD: We conducted a joint site assessment and designed laboratories for the expansion of DNA polymerase chain reaction (PCR) testing based on dried blood spot (DBS) for EID in six regions of Ethiopia. Training of appropriate laboratory technologists and development of required documentation including standard operating procedures (SOPs) was carried out. The impact of the expansion of EID laboratories was assessed by the number of tests performed as well as the turn-around time. RESULTS: DNA PCR for EID was introduced in 2008 in six regions. From April 2006 to April 2008, a total of 2848 infants had been tested centrally at the Ethiopian Health and Nutrition Research Institute (EHNRI) in Addis Ababa, and which was then the only laboratory with the capability to perform EID; 546 (19.2%) of the samples were positive. By November 2010, EHNRI and the six laboratories had tested an additional 16 985 HIV-exposed infants, of which 1915 (11.3%) were positive. The median turn-around time for test results was 14 days (range 14-21 days). CONCLUSION: Expansion of HIV DNA PCR testing facilities that can provide quality and reliable results is feasible in resource-limited settings. Regular supervision and monitoring for quality assurance of these laboratories is essential to maintain accuracy of testing.

Evaluation of blood collection filter papers for HIV-1 DNA PCR.

BACKGROUND: The collection of dried blood spots (DBS) on Whatman 903 cards has facilitated for years the detection of HIV-1 in infants by DNA PCR as early as 4-6 weeks after birth in resource-limited settings (RLS), but alternate blood collection devices are proving to be necessary. OBJECTIVES: The qualitative detection of HIV-1 DNA by PCR from DBS prepared on three commercially available blood collection cards was evaluated at the Centers for Disease Control and Prevention (CDC) and in four laboratories in Africa. STUDY DESIGN: DBS were prepared on Ahlstrom grade 226, Munktell TFN and Whatman 903, and stored under a variety of conditions. DBS were stored at ambient temperature (RT), 37°C with high humidity, and -20°C for varying lengths of time. The presence of HIV-1 DNA was tested using Roche Amplicor HIV-1 DNA (v 1.5) weekly for 4 weeks and at weeks 8 and 12 (RT and 37°C), at weeks 4, 8, and 18 (-20°C) of storage. DBS specimens were also tested after international shipment at RT. In addition, after nearly 3 years storage at -20°C, DBS were also evaluated independently using the COBAS Ampliprep/TaqMan HIV-1 Qual and Abbott RealTime HIV-1 Qualitative tests. RESULTS: HIV-1 DNA was detected equally well on the three blood collection cards regardless of storage conditions and PCR assay. CONCLUSIONS: Ahlstrom 226 and Munktell TFN papers were comparable to Whatman 903 for HIV-1 DNA detection and may be considered as optional blood collection devices in resource-limited countries.

Reverse transcriptase activity for quantitation of HIV-1 subtype C in plasma: relation to RNA copy number and CD4 T-cell count.

The present study monitored the changes in human immunodeficiency virus (HIV) viral load using a reverse transcriptase (RT) assay and an HIV-1 RNA based assay, and relates these data to the dynamics of CD4 cell counts. The samples examined originate from a prospective study of HIV-1 subtype C infected, untreated Ethiopians followed twice yearly over a period of up to 5 years. The ExaVir Load test, version 1, was used for isolation and quantitation of HIV-1 RT in plasma. The RT activities recovered were compared to the HIV-1 RNA copy numbers, which had been determined previously by the NucliSens HIV-1 QT Test. There was a significant correlation between the data obtained in the two tests (r = 0.65, P < 0.0001). During follow-up, the median RT and RNA levels increased more or less in parallel up to approximately four times the values at admittance. CD4 cell counts, which had also been determined previously, decreased slowly but continuously from approximately 310 to 190 CD4 cells/ml. In the majority of individual patients, there was an inverse correlation between CD4 T-cell counts and RT activity, and with the RNA copy number, and the data obtained by either test could be used to predict CD4 T-cell counts. The ExaVir Load test thus provides data equivalent to the estimation of the number of HIV-1 RNA copies for the prediction of CD4 T-cell counts. It is based on a simple technique, can be run in any routine diagnostic laboratory, and is a competitive alternative for use in resource limited settings.