False-negative HIV antibody test results

Ideally HIV antibody tests have to be both extremely sensitive and able to recognize all known HIV subtypes. Three patients whose sera failed to react with a synthetic oligopeptide-based HIV antibody test are described in thi s report. The patients were a Pakistani male infected recently, an Australi an male infected for several years, and a Ugandan woman with AIDS. The pres ence of anti-HIV antibodies was confirmed by means of a standard algorithm with different assay formats. All three sera failed to react in one antiglo bulin enzyme-linked immunosorbent assay (ELISA) (Bioelisa HIV-1+2, Biokit S A). No single underlying reason could be identified for the assay failure i n the three cases. The first patient, probably infected recently when first tested, was strongly positive by the same assay a year later, confirming t he relative insensitivity of oligopeptide assays reported previously for de tecting the early antibody response. The other two patients appear to have been infected for several years. Although unlikely to have been infected wi th a non-clade B virus, the sample from patient 2 lacked detectable antibod y to the transmembrane glycoprotein (gp41), the site of the synthetic oligo peptides. Patient 3, of Ugandan origin, was found to be infected with a non -clade B virus. Although her serum reacted strongly to subtype B gp41 in We stern blot, it failed to react in the antiglobulin ELISA. Since there appea rs to be no single common explanation for these three failures there is lit tle opportunity to identify prospectively those situations where testing us ing assays employing synthetic oligopeptides on the solid phase is likely t o fail. J. Med. Virol. 60:43-47, 2000. (C) 2000 Wiley-Liss, Inc.