Evaluation of the World Health Organisation antibody-testing strategy for the individual patient diagnosis of HIV infection (strategy III).
OBJECTIVE
To evaluate the World Health Organisation (WHO) antibody testing strategy for the individual patient diagnosis of HIV infection (strategy III).


METHODS
Evaluation of a combination of enzyme-linked immunosorbent assays (ELISAs) for the detection of antibodies to HIV-1 and HIV-2 infection. The WHO strategy III calls for a combination of three ELISAs, based on different antigens and/or differing test principles, to be used in a sequential fashion. The first part of the study evaluated various kits as part of a selection process. The second part of the study was an assessment of the three-ELISA testing strategy on routine sera submitted to the National Institute for Virology (NIV) for HIV testing. In all instances, the conventional testing protocol, which utilises a screening ELISA followed by a confirmatory Western blot (WB) on positive specimens, was used as the 'gold standard'.


METHODS
The HIV-testing laboratory at the NIV, Johannesburg.


RESULTS
In the first part of the study, all of the ELISA kits evaluated showed high sensitivity and specificity, and a selection of the kits for part two of the study was made in accordance with the WHO recommendation. The kits selected, in order of use, were the Biotest anti-HIV 1/2 (test 1), Pasteur Genelavia Mixt HIV-1/2 (test 2) and Murex Wellcozyme HIV-1 competitive assay (test 3). This combination was evaluated using 7,812 sera submitted to the NIV for serology testing. The sensitivities of the tests were highly satisfactory (99.6-100%) as were the specificities (99.2-100%). The positive predictive value of strategy III at various seroprevalence (0.5-25.5%) was > or = 99.6%. The rate of WB usage when compared with the previous HIV testing protocol was low (4.6%).


CONCLUSIONS
The results of this study suggest that this testing protocol could be introduced in South Africa with considerable cost-saving and no reduction in specificity.
MRC AIDS Virus Research Unit, National Institute for Virology, Johannesburg.
D J
DJ
Martin
N K
NK
Blackburn
K F
KF
O'Connell
E T
ET
Brant
E A
EA
Goetsch
D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005069:Evaluation Studies as Topic; D015483:HIV Antibodies / Q000097:blood*; D015658:HIV Infections / Q000175:diagnosis*; D006801:Humans; D012680:Sensitivity and Specificity; D014944:World Health Organization
D015483:HIV Antibodies