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Environmental assessment on the proposed field use of live the recombinant vaccinia-rabies glycoprotein vaccine Raboral VR-G for the immunization of raccoons

For Public Release

February 15, 1996

The information in this environmental assessment was current at the time of its preparation. It is possible that the situation may have changed since that time. Please consult the Veterinary Biologics Section (VBS) if you have any questions.


This environmental assessment was prepared in 1996 prior to the field use of the vaccinia-rabies glycoprotein vaccine VR-G in Ontario for controlling rabies in wildlife. The assessment was prepared by Agriculture and Agri-Food Canada (AAFC) [predecessor of the Veterinary Biologics Section (VBS) of the Canadian Food Inspection Agency (CFIA)] in collaboration with Environment Canada (EC) and Health Canada (HC). Provided below is the Summary and Decision section from the original document. A printed copy of the complete environmental assessment can be obtained from CFIA-VBS.


Summary and decision

Vaccinia-rabies glycoprotein (VR-G) vaccine consists of live vaccinia virus, modified by the introduction of rabies glycoprotein gene into the thymidine kinase gene sequence of vaccinia (Raboral VR-G® Rabies Vaccine, Live Vaccinia Vector — Rhone Merieux, Inc., Georgia, United States (U.S.)). The Ontario Ministry of Natural Resources (OMNR) has requested permission from AAFC for the limited field use of the vaccine in the Niagara region of Ontario with the aim of developing an effective oral immunization program to control ‘raccoon rabies'.

Prior to the authorization of limited field use of VR-G vaccine, a comprehensive assessment of the potential risks associated with the field release of VR-G vaccine was undertaken by AAFC in collaboration with EC and HC. The details of that assessment are presented in this ‘Environmental Assessment' document. Special attention was given to the evaluation of safety, which included consideration of biological safety characteristics, human safety and animal safety of the vaccine.

The document discusses the safety studies carried out in the laboratory using both target and non-target animal species, and clinical observations conducted under field trial conditions. Experiments in mice have indicated that the vaccine organism is of reduced pathogenicity compared to the parental organism due to the insertional inactivation of the thymidine kinase gene of vaccinia virus. Following oral administration, vaccine organism may survive for a short duration (for up to 48 hours) in the buccal cavity of foxes and raccoons. During this period, virus may be transmitted mechanically to animals in close contact with the vaccinates. However, this method of transmission is not likely to be a significant route of spread of the organism in the field application of the vaccine. No faecal shedding of the organism or systemic spread to internal organs following oral administration of the vaccine has been observed in immunocompetent animals from any target or non-target species tested.

The document also discusses the molecular and biological characteristics of the recombinant organism in relation to the parental organisms. Experiments carried out by AAFC and the manufacturer, established the genetic stability and purity of the vaccine organism.

The risk factors considered in the evaluation of human health and safety of recombinant VR-G vaccine were, the potential to cause disease or pathogenicity, potential to cause post vaccination complications, oncogenicity, ability of the vaccine organism to overcome the attenuated state and the potential to cause complications in immunocompromised individuals. Characterization and analysis of risk factors used for each of the above categories, suggested that the field use of this wildlife vaccine is unlikely to pose a significant risk to human health.

No negative impacts on the environment have been reported following field use of VR-G vaccine in Belgium, France and U.S. During the course of these field trials, both target and non-target animals were examined for signs of clinical disease that could be attributed to immunization with the recombinant vaccine. None of the animals had lesions suggestive of disease with poxvirus aetiology.

Based on the field trial findings; laboratory safety studies submitted by the manufacturer; the scientific assessment conducted by Canadian Cooperative Wildlife Health Centre on behalf of EC; the quantitative risk assessment of the Animal and Plant Health Risk Assessment Network; and the review by HC, no significant adverse impact of VR-G vaccine either on the health of the target and non-target animal species or on humans is anticipated following its field use in Ontario. Therefore, the request for limited field use of the VR-G vaccine by the OMNR will be authorized on a ‘case by case basis' under the Health of Animals Act and Regulations, subject to conditions specified for its field use. These conditions include information that should be provided before the initiation of the immunization campaign such as descriptions of the trial site, field trial design, sampling and monitoring strategies; human safety measures; contingency plans; animal safety and surveillance measures; requirements for handling and transport of bait vaccine; and communication plans surrounding the field release of the vaccine. It is proposed that the field use of the vaccine be monitored by a committee representing the federal and the provincial governments with relevant authority concerning agriculture, wildlife, human health and environment.