EVALUATION OF AN ANIMAL RABIES VACCINE BY USE OF 2 TYPES OF POTENCY TESTS

Objective-To evaluate the potency of an inactivated animal rabies vacc ine for domestic animals by use of 2 types of potency tests after chal lenge exposure with a laboratory standard virus or 1 of 5 viruses obta ined from various wildlife species. Animals-384 mice vaccinated twice intraperitoneally; 384 mice vaccinated once IM. Procedure-Mice vaccina ted with an inactivated, adjuvanted rabies vaccine for domestic animal s were challenge exposed with the common fixed challenge virus or 1 of 5 rabies viruses obtained from wild animal species (street viruses) t hat most commonly transmit the virus in the United States and Canada. Potency tests included 2 types of antigen extinction tests: the Nation al Institutes of Health (NIH) test and the Centers for Disease Control test. Results-Results of both tests indicated that protection was hig hest against raccoon and bat viruses. Marked differences were detected in the relative potency ratios for the NIH versus the Centers for Dis ease Control tests, though the relative potencies themselves (against the street viruses) did not differ markedly. Conclusions-The markedly reduced potency against the street Viruses indicated by the NIH test r esults was suggestive of an inherent bias associated with double intra peritoneal vaccination and intracerebral challenge exposure, whereas t he single IM vaccination and IM challenge exposure reduced that bias.