Laboratory diagnosis of dual HIV-1/HIV-2 infection in Ghanaian patients

Abstract

To determine the true prevalence of HIV dual infections in a previously characterised HIV seropositive patient group due to inconsistencies between different diagnostic methods. A cross-sectional study of an HIV seropositive group with different diagnostic methods. Setting: Three hospitals in the Northern, Ashanti and Greater Accra Regions of Ghana. One hundred and forty five HIV infected patients/individuals sampled from June to September 2002. Main Outcome Measures: Using serological and molecular methods, the seropositive status of HIV-infected patients, previously determined by a preliminary screening process, was confirmed and discrepancies noted. The data was used to propose a more accurate laboratory diagnosis of HIV dual infections involving HIV-1 and HIV-2. Result: HIV-1 infections were mostly accurately detected, but difficulties were encountered in diagnosing HIV-2 infections. To achieve a positive detection on confirmatory immunoblots, antibody concentration in some samples tested was enhanced by using larger volumes. In other cases, diagnosis of HIV infections by PCR, especially HIV-2, was possible only after increasing the DNA template or MgCl2 concentrations. Such samples would otherwise have been inaccurately scored for HIV infections. Conclusion: Based on the results of this study, we propose that the accurate diagnosis of HIV dual infections, especially HIV-2 component, must use an algorithm that involves PCR. Our results however underscore conclusions of a previous study that most dually seroreactive samples are predominantly HIV-1 infections with crossreactivity to HIV-2 antigens.