Detection of HIV-1 p24 antigen in patients with varying degrees of viremia using an ELISA with a photochemical signal amplification system.

Background: We describe a photochemical signal amplification method (PSAM) for increasing the sensitivity of enzyme-linked immunosorbent assays (ELISAs) for the detection of HIV-1 p24 antigen, and present a preliminary validation study on ELISA+PSAM technology for detection of HIV-1 p24 antigen in clinical samples.

Methods: ELISA+PSAM is compatible with commercially available microtiter plate readers, employs an inexpensive illumination device and the amplification takes around 10 min.

Results: The PSAM technology not only increases the analytical sensitivity for detection of HIV-1 p24 antigen by approximately 40 times, but also significantly increases the clinical sensitivity of the ELISA: in instances where viral RNA load is <3000 copies/ml, conventional heat mediated immune complex disruption ELISA (HM-ELISA) cannot detect any HIV positive samples whereas HM-ELISA+PSAM can detect HIV infection in approximately half of the samples (clinical sensitivity is 52.63%). For viral RNA loads between 3000 and 30,000 copies/ml, the clinical sensitivities of the HM-ELISA and HM-ELISA+PSAM are 32.6% and 91.3%, and for that >30,000 copies/ml, clinical sensitivities of HM-ELISA and HM-ELISA+PSAM are 52.3% and 100%, respectively.

Conclusions: The HM-ELISA+PSAM represents an advancement in monitoring HIV-1 disease progression and treatment in the global healthcare setting.