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HIV antigen–antibody combination enzyme immunoassay—the experience of a London Teaching Hospital
Author(s) -
Goldenberg Simon,
Kulasegaram Ranjababu,
Peters Barry,
Panayotakopoulos George,
Tong C.Y. William
Publication year - 2007
Publication title -
journal of medical virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 121
eISSN - 1096-9071
pISSN - 0146-6615
DOI - 10.1002/jmv.20964
Subject(s) - window period , medicine , immunoassay , human immunodeficiency virus (hiv) , antibody , hiv screening , antigen , hiv diagnosis , virology , immunology , viral load , serology , antiretroviral therapy , syphilis , men who have sex with men
The introduction of the fourth generation HIV antigen–antibody combination enzyme immunoassay (HIV Ag–Ab EIA) has led to a reduction in the diagnostic “window period” when HIV antibody is negative during primary infection. This facilitates earlier laboratory diagnosis during sero‐conversion. An HIV Ag–Ab EIA (AxSYM, Abbott Laboratories, Kent, UK) was introduced to a London Teaching Hospital since 2004 as the primary screening test. Confirmation was performed using another HIV Ag–Ab EIA (Vironostika, BioMérieux, Hampshire, UK) and an HIV Ab only assay (Bispot, Orgenics, Yavne, Israel). Retrospective analysis identified a total of 20 sero‐converting patients who would have been missed if the standard antibody‐only HIV tests had been used as the primary screening test. This accounted for approximately 3% of the new diagnoses made by the laboratory. The median time from onset of illness to sero‐conversion was 18 days. Two patients had multiple samples analyzed between initial presentation and eventual sero‐conversion. One had a prolonged sero‐conversion illness lasting for over 137 days; the other sero‐converted within 17 days. A plotting of the signal to cut‐off ratio with time of the two HIV Ag–Ab EIAs showed a V‐shaped curve and both tests were below cut‐off at some time‐points during sero‐conversion. These two cases highlighted the difficulties in diagnosing HIV infection during sero‐conversion. On the basis of these results, it is recommended that a fourth generation HIV Ag–Ab EIA could be considered for use as the standard of care, particularly in any population with a high rate of HIV infection. J. Med. Virol. 79:S23–S26, 2007. © 2007 Wiley‐Liss, Inc.