Evaluation of HIV Western Blot Test Kits for HIV Confirmatory Diagnosis in Japan

Abstract

The performance and the cross-reactivity to HIV-1 and HIV-2 between NEW LAV BLOT I and II,which are Western blot kits for HIV-1 and HIV-2, respectively, were evaluated using 89 HIV-1-positive specimens collected in Japan from 2013 to 2015 and 34 specimens in commercial anti HIV-1/2 Combo Performance Panels. HIV-1 positive specimens collected in Japan were detected almost perfectly using NEW LAV BLOT I. The true positive rate was higher based on the CDC criteria (98.9%) than on the WHO criteria (95.5%). When the same specimens were tested using NEW LAV BLOT II, 12 of them were determined to be HIV-2 positive following the criteria described in an attached manual and thus judged as “untypable”. However, all of these specimens were judged indeterminate based on the WHO criteria and thus they were not judged as ”untypable”. From the results obtained using anti HIV-1/2 Combo Performance Panels, the true positive rate of HIV-1-positive specimens tested using New LAV BLOT I was higher based on the CDC criteria (84.6%) than on the WHO criteria (46.2%). However, because 6 of 13 HIV-2-positive specimens were determined to be HIV-1 positive following the CDC criteria, these specimens became “untypable”. Considering the current HIV epidemic in Japan, we should apply NEW LAV BLOT I first to perform confirmatory tests of screening-test positive specimens. When the result is negative or indeterminate, a confirmatory test using NEW LAV BLOT II is useful the PCR findings of HIV-1 RNA are negative and the patient is at some risk of HIV-2 infection. When NEW LAV BLOT I and II are used for discrimination of HIV-1 and 2 infections in parallel, we might use the WHO criteria.