Human immunodeficiency virus (HIV) antibodies detected by new assays that are enhanced for HIV-1 subtype O

Development of multiplexed nucleic acid testing for human immunodeficiency virus type 1 and hepatitis C virus

BACKGROUND AND OBJECTIVES

In most Western countries, blood donations are routinely screened for hepatitis C virus (HCV) RNA by polymerase chain reaction (PCR) or other nucleic acid tests. We describe the development of a multiplexed assay for human immunodeficiency virus type 1 (HIV-1) and HCV in an internally controlled PCR suitable for large-scale blood donor screening.

MATERIALS AND METHODS

The HIV/HCV multiplexed PCR used primers from highly conserved regions in the long terminal repeat region. The National Institute for Biological Standards and Controls (NIBSC) International HIV-1 RNA standard, run control and HIV-1 subtype panel were used for assay evaluation.

RESULTS

The HIV-1 PCR showed a sensitivity of 24 IU/ml for HIV-1 RNA (a dilution where 95% of replicate reactions were positive), which was at least five times more sensitive than the Roche Monitor version 1.5 (using the ultrasensitive extraction protocol) and Organon NASBA assays. The assay was capable of detecting all subtypes of HIV-1 (A to H), as well as the more divergent group N and O variants. The sensitivity of the PCR was unaffected by multiplexing with HCV primers and by the presence of a bovine viral diarrhoea virus (BVDV) internal control.

CONCLUSION

We have developed a highly sensitive multiplexed PCR for HIV-1 and HCV RNA screening that can be introduced into current PCR-based blood donor screening at minimal cost and without significant operational changes.

A comparative meta-analysis on the variability in test performance among FDA-licensed enzyme immunosorbent assays for HIV antibody testing

BACKGROUND

Although independently published studies have compared diagnostic test performance among various manufactured enzyme immunosorbent assays (EIAs) used in HIV antibody testing, none have attempted to formally synthesize such results through a comparative meta-analysis. In particular, no estimates of post-FDA approval test performance, in terms of sensitivity and specificity, and their associated variability within each manufacturer, has been reported in the literature, along with an analysis of the relative differences in manufacturer test performance in practice (after FDA approval).

METHODS

Retrieval of studies was done using several searching strategies, while retrieval of manufacturer information was done through package inserts and direct contacts. Comparisons of HIV antibody test performance across manufacturers and within a single manufacturer were made based on 16 estimates (from 11 articles) and 33 estimates (from 19 articles), respectively. A generalized linear model, based upon Bayes estimates of sensitivity and specificity, was used to assess the impact of several study-level covariates on the performance of these EIAs, with overall estimates of manufacturer test performance and associated variability obtained based on generalized estimating equations.

RESULTS

Estimates of test performance were obtained across studies, with a significant (P < 0.01) difference between manufacturers. The test performance of each manufacturer significantly interacted (P < 0.05) with the following study-level covariates: type of population screened, year of diagnostic testing and study quality. Among a single manufacturer, Abbott, significant improvement in estimates of test sensitivity (P < 0.01) and specificity (P < 0.01) was observed with each newly produced antibody kit.

CONCLUSION

Estimates on the relative differences in test performance within each manufacturer may be used for guiding decisions on the choice of EIA test kit for HIV antibodies, given the type of population screened, as well as cost and time considerations. In addition, the results of this meta-analysis may be used in modeling HIV prevalence when used as prior information within a Bayesian framework or for standardizing test results among various manufacturers.

Anti-HIV indeterminate western blot in dialysis patients: a long-term follow-up

In a group of 520 patients undergoing chronic hemodialysis, 23 (4. 4%) were enzyme immunoassay (EIA) positive for human immunodeficiency virus (HIV) and indeterminate by Western blot (IWB) analysis. The antibodies were mostly directed against p24 and p55 antigens. A comparison between hemodialysis patients with and without IWB showed significant differences between the two groups with respect to number of units of blood transfused, history of renal transplant rejection, and Rh status. No significant differences were observed with respect to ethnic group, nature of renal disease, duration of hemodialysis, associated diseases, and ABO blood group. The HIV IWB phenomenon may represent abnormal immune reactivity as a result of transplantation antigens and/or autoantibody formation. Five-year follow-up of the HIV EIA-positive IWB patients showed that none had seroconverted to HIV-positive status.