Assesment of recent HIV-1 infection by Western blot in dried blood spots

Background: Project AMPLIAR is a research consortium developed in part to evaluate testing methods to detect recent infections in south Brazil applicable to resource-limited settings. Recent reports have suggested that antibody specificity patterns (i.e. bands on LIA or WB) can be useful for both confirmation of infection and for simultaneous staging of infections as recent or longer-term infections. We wished to investigate whether Western blot (WB) could be used for this dual purpose using dried blood spots (DBS).
Methods: In a cross-sectional diagnostic performance evaluation from September 2006 to August 2007, we screened DBS from 101 consecutive HIV+ samples collected by Projeto AMPLIAR using both WB (DAVIH Blot HIV-1 DBS) and BED-CEIA (Calypte HIV-1 BED Incidence Capture EIA) assays. We assessed a variety of WB band patterns identified in the literature as having the ability to distintuish recent (<~154 days) from long-term infection, using a BED normalized OD (ODn)<0.8 as the reference standard for recent HIV infection.
Results: BED-CEIA classified 14 of 101 positive individuals (13,5%, 95% CI, 7,0-20,7) as recently infected. A WB algorithm requiring the absence of gp120, p24, p55 and p34 was able to identify recent HIV infections with the highest accuracy (77.2%), with a sensitivity of 57,1% (95% CI, 28,8-85,5) and specificity of 80,5% (95% CI, 72,0-88,9). Previously suggested algorithms based on raw band count or intensity scores were markedly less sensitive. Absence of the p31 (p34) band, suggested in the literature as being ‘characteristic’ of recent infection, was found in only 2 of 14 patients with recent infection (sensitivity=14%).
Conclusions: WB can be used to confirm HIV infection on DBS in situations with limited laboratory infrastructure where samples can be mailed to a centralized laboratory. However, our preliminary results suggest that WB patterns alone may have limited utility in discerning recent from long term infections in these settings.

L.R. Motta1, S.K. Kato1, R.D. Sperhacke1, L.G.A. Borges1, C.D. Pilcher2, R.S. De Souza1
1Laboratório de Pesquisa em HIV/AIDS, Universidade de Caxias do Sul, Caxias do Sul, Brazil, 2University of California-San Francisco, San Francisco, United States