ENHANCED CHEMILUMINESCENCE AS A MEANS OF INCREASING THE SENSITIVITY OF WESTERN-BLOT ASSAYS FOR HIV ANTIBODY

Chemiluminescence indicator systems offer several advantages for diagnostic assays and have been used successfully to increase the sensitivity of antibody and antigen assays. A technique of enhanced chemiluminescence (ECL) was applied as a replacement for routine chromogenic substrates on HTV-1 Western blots. The results indicated that the enhanced chemiluminescence detection system increased the sensitivity by greater than 10-fold over routine chromogenic indicator systems when testing diluted, reactive sera. When testing 9 seroconversion panels, the use of ECL indicated that early detection of HIV infection was elicited in six panels up to 31 days (average 11.4 days) prior to detection by routine FDA-licensed Western blots, and could be detected in all panels up to 43 days (average 18.8 days) prior to detection by in-house Western blots. In no case was the ECL Western blot system less sensitive than any of the chromogenic Western blots, and in several cases the maximum potential of the ECL system for early detection of antibody could not be determined. The ECL system was capable of detecting antibodies to envelope antigens at a 20-fold increase over chromogenic Western blots. The time of detection of seropositivity by the ECL Western blot was equal to that of most ELISAs in 5 panels and was 31 days earlier than ELISA in one panel. Permanent documentation of Western blot profiles was accomplished using a simple instamatic camera system capable of detecting the chemiluminescence signal, and blots could be re-probed using a second sample. It is concluded that the application of an enhanced chemiluminescence detection system for HIV Western blots can increase sensitivity, detect infection earlier than standard Western blots, and has the potential to resolve HIV-1 Western blot indeterminate results.