engleski

Is Western blot alone sufficient to confirm a reactive result of a fourth-generation HIV screening assay?

Many countries have recently placed significant emphasis on the identification of people with acute HIV infection. This is important for several reasons. Firstly, acute HIV provides a unique view of HIV transmission and pathogenesis, including early hostvirus interactions and these require further studies. Secondly, prevention strategies directed at subjects with acute HIV infection could have significant impact. Thirdly, very early recognition may allow for HIV treatment that could alter the natural progression of disease. The standard HIV antibody screening test (third-generation) has therefore been replaced by the more sensitive fourth-generation and new serological testing algorithms for recent HIV seroconversion have been introduced. Recently, some laboratories have also begun adding HIV nucleic acid amplification testing to HIV diagnostic testing algorithms so that acute (antibody-negative) HIV infections can be routinely detected within the first 1– 3 weeks of exposure in about 50% of patients and thereafter up to 80 days in the remaining ones. In our case we have shown that, despite clinical suspicion, an early HIV infection can still be missed using Western blot as the sole confirmatory method in patients with an early HIV infection in whom only the HIV antigen is detectable and antibodies have not yet been produced. In addition, comments about possible non-specific reaction with the suggestion of a control at a later time can be misunderstood and consequently mistakenly ignored by both the physician and the patient. Following this, the patient can disappear and reappear later in a different setting with all the complications of disease progression, late therapy, possible unrecognized transmission of a resistant virus and infection of the environment and contacts. Specifically, reactive fourth-generation HIV screening tests should be confirmed properly in the first sample and all possible diagnostic tests need to be exploited at this point as the patient may later be lost to follow up. This case leads us to recommend that in patients with reactive HIV EIA fourth-generation, with or without clinical illness, a negative immunoblot result should be followed by nucleic acid amplification testing or a p24 antigen immunoassay with confirmatory ability using the neutralization principle. This would optimize early HIV diagnosis without a significant cost increase considering the benefits accruing in terms of opportunities for earlier treatment, source identification and introduction of preventive measures.

Western blot; confirmation; fourth-generation; HIV screening

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