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  • Author or Editor: George M. Baer x
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Abstract

Objective

To evaluate the potency of an inactivated animal rabies vaccine for domestic animals by use of 2 types of potency tests after challenge exposure with a laboratory standard virus or 1 of 5 viruses obtained from various wildlife species.

Animals

384 mice vaccinated twice intraperitoneally; 384 mice vaccinated once IM.

Procedure

Mice vaccinated with an inactivated, adjuvanted rabies vaccine for domestic animals were challenge exposed with the common fixed challenge virus or 1 of 5 rabies viruses obtained from wild animal species (street viruses) that most commonly transmit the virus in the United States and Canada. Potency tests included 2 types of antigen extinction tests: the National Institutes of Health (NIH) test and the Centers for Disease Control test.

Results

Results of both tests indicated that protection was highest against raccoon and bat viruses. Marked differences were detected in the relative potency ratios for the NIH versus the Centers for Disease 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 results was suggestive of an inherent bias associated with double intraperitoneal vaccination and intracerebral challenge exposure, whereas the single IM vaccination and IM challenge exposure reduced that bias. (Am J Vet Res 1997;58:837–840)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effect of various routes of administration and number of doses of 3 commercially produced rabies vaccines on serum antibody responses and protection in mice challenged by intracerebral injection with fixed-strain rabies virus.

Animals—2,213 mice.

Procedure—Inactivated, adjuvanted rabies vaccines were administered to mice in either 2, 1, or 0 (control) doses via IP, IM, and SC routes, and mice were challenged intracerebrally with fixed-strain rabies virus.

Results—Vaccination route and dose number significantly influenced serum antibody responses and protection from rabies virus challenge, independent of vaccine strain origin and mouse strain, although mouse age significantly affected results. Extended challenge studies revealed that IM vaccination of mice resulted in the highest serum neutralizing antibody responses and protection levels equivalent to IP vaccination. Even multiple doses administered SC (a vaccination route used in dogs) resulted in poor serum anti-rabies neutralizing antibody responses in mice and were far less protective than other routes.

Conclusions and Clinical Relevance—Findings suggest possible improvements for the current rabies vaccine potency test in mice by using 1 dose, the IM route, and a delayed time of challenge. These modifications would more closely model vaccination practices in target species and yield more accurate information regarding primary immunogenicity of a vaccine. (Am J Vet Med 2003;64:491–498)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine effect of route of challenge and strain of rabies virus on efficacy of inactivated rabies vaccines in mice.

Animals—3,056 mice.

Procedure—Challenge was performed with fixed and street rabies virus strains by use of footpad and intracerebral routes as well as IM injection into the hip, shoulder, neck, and masseter muscles. Intraperitoneal and IM vaccination was performed with 1 or 2 doses of 1 of 3 vaccine-strain inactivated rabies vaccines. For 2 of the vaccine strains, the vaccines were adjuvanted and nonadjuvanted.

Results—Incubation periods were dependent on route, dose, and virus strain used for challenge. Use of an intramasseter challenge route with challenge virus-strain rabies virus, which more accurately models natural exposure to rabies virus, resulted in reproducible mortality rates in mice. Use of this route revealed that differences among vaccines and challenge virus strains affected mortality rate less than that observed in the National Institutes of Health potency test, even when street isolates of widely variant origin were used for challenge.

Conclusions and Clinical Relevance—These results, combined with earlier data, support a proposal for a new rabies potency test that more closely models current vaccine administration practices and natural infection routes. (Am J Vet Res 2003;64:499–505)

Full access
in American Journal of Veterinary Research