A comparative study between in vivo and in vitro methods for potency evaluation of Rabies vaccine preparations

Abstract

The present study was concerned with the evaluation and correlation between three important methods National Institute of Health test (NIH), Rapid Focus Fluorescent Inhibition Test (RFFIT), and Passive Hemagglutination test (PHA)-used in potency determination for rabies vaccine preparations. The aim was to know the availability of replacement of the main NIH test for potency evaluation due to its great drawbacks like consumption of large number of animals, non-humane endpoints of the test, and also high variability of the test due to its in vivo nature. The study was also concerned with validation of both in vitro methods – Rapid Focus Fluorescent Inhibition test (RFFIT), and Passive Hemagglutination test (PHA) against the NIH test. In this study, 25 rabies vaccine preparations of a single company were used for potency determination using the three methods mentioned before. The mean of potencies for the three methods were 3.73, 3.51, and 4.50, respectively. All results were within the acceptable limit which not less than 2.5 IU/ml.