Evaluation of particle agglutination test for detection of HIV-I antibodies

A commercially available particle agglutination test (PA) was evaluated for its specificity and sensitivity as compared to ELISA currently used in our laboratory to detect HIV-I antibodies. A total of 463 sera from blood donors and clinical referrals were screened by PA, 45 were found to be positive (9.7%). Out of 463, 258 sera were simultaneously screened by ELISA; 28 were found to be positive (10.8%). Twelve samples showing positive results by both ELISA & PA were tested by Western blot and were confirmed to be positive. We found sensitivity of PA as compared to ELISA as 100% and specificity to be 88.44%. Readings of PA taken at 2 hrs should be reconfirmed at 24 hrs as it eliminates a number of false positives. Overall, we feel PA is fairly comparable with ELISA. It can be used in the set up where equipment and trained personnel for ELISA are not available for primary screening purposes.