Current HIV-2 diagnostic strategy overestimates HIV-2 prevalence in China

A significant number of HIV-2 infections have been reported in China using Western blot as per current guidelines for HIV-2 diagnosis in China. However, most specimens were also positive on HIV-1 Western blot suggesting cross-reactivity and possible overestimation. We carried out the current study to evaluate a strategy to diagnose the HIV-2 infections in China. A total of 119 specimens received from 16 provinces were likely to be HIV-2 when tested according to current guidelines in China using the Genelabs Western blot (HIV Blot 2.2 WB). Further testing by HIV-2 WB (Bio-Rad New LAV Blot II or Genelabs HIV Blot 1.2 WB) scored 56 (47.1%) of 119 samples with banding pattern suggestive of HIV-2 infection, and 63 (52.9%) were HIV-2 indeterminate. A peptide-based HIV-1 and HIV-2 enzyme immunoassay for differential diagnosis of HIV-1 and HIV-2 infections was validated and used. This in-house EIA demonstrated that only 1 (0.8%) of 119 specimens had HIV-2 specific antibodies, while 2 (1.7%) were dually reactive. These results were highly concordant (>99%) with those by Inno-LIA HIV-I/II (Innogenetics, Belgium), which also use specific peptides for type-specific diagnosis. Our data demonstrates that HIV-2 infection is rare in China, and HIV-2 Western blot may overestimate the prevalence of HIV-2 in the population with HIV-1. The HIV-2 diagnostic strategy in China needs to be revised to include more specific peptide-based immunoassays.