Evaluation of the Limiting Antigen Avidity EIA (LAg) among people who inject drugs in Greece

• Published in: Epidemiology and infection Vol. 145; no. 2; pp. 401 - 412
• Main Authors: NIKOLOPOULOS, GK, KATSOULIDOU, A., KANTZANOU, M., ROKKA, C, TSIARA, C., SYPSA, V., PARASKEVIS, D., PSICHOGIOU, M., FRIEDMAN, S., HATZAKIS, A.
• Format: Journal Article
• Language: English
• Published: 26.10.2016
• ISSN: 0950-2688; 1469-4409
• DOI: 10.1017/S0950268816002417

This analysis assessed the utility of the Limiting Antigen Avidity (LAg) assay. Samples of people who inject drugs (PWID) in Greece with documented duration of HIV-1 infection were tested by LAg. A LAg normalized Optical Density (ODn) less than 1.5 corresponds to a recency window period of 130 days. The proportion true (PTR) and false (PFR) recent were estimated in 28 seroconvertors and in 366 samples collected more than 6 months after the HIV diagnosis, respectively. The association between LAg ODn and HIV RNA level was evaluated in 232 persons. The PTR was 85.7%. The PFR was 20.8% but dropped to 5.9% in samples from treatment naive individuals with long-standing infection (>1 year) and to 0 in samples with the circulating recombinant form CRF35 AD. A LAg-based algorithm with a PFR of 3.3% estimated a similar incidence trend to that calculated by analyses based on HIV-1 seroconversions. In recently infected persons indicated by LAg, the median log10 HIV RNA level was high [5.30, Interquartile Range (IQR): 4.56–5.90]. LAg can help identify highly-infectious HIV (+) individuals as it accurately identifies recent infections and is correlated with HIV RNA level. It can also produce reliable estimates of HIV-1 incidence.