Process optimization and scale-up for production of rabies vaccine live adenovirus vector (AdRG1.3)

Rabies virus is an important causative agent of disease resulting in an acute infection of the nervous system and death. Although curable if treated in a timely manner, rabies remains a serious public health issue in developing countries, and the indigenous threat of rabies continues in developed countries because of wildlife reservoirs. Control of rabies in wildlife is still an important challenge for governmental authorities. There are a number of rabies vaccines commercially available for control of wildlife rabies infection. However, the vaccines currently distributed to wildlife do not effectively immunize all at-risk species, particularly skunks. A replication competent recombinant adenovirus expressing rabies glycoprotein (AdRG1.3) has shown the most promising results in laboratory trials. The adenovirus vectored vaccine is manufactured using HEK 293 cells. This study describes the successful scale-up of AdRG1.3 adenovirus production from 1 to 500 L and the manufacturing of large quantities of bulk material required for field trials to demonstrate efficacy of this new candidate vaccine. The production process was streamlined by eliminating a medium replacement step prior to infection and the culture titer was increased by over 2 fold through optimization of cell culture medium. These improvements produced a more robust and cost-effective process that facilitates industrialization and commercialization. Over 17,000 L of AdRG1.3 adenovirus cultures were manufactured to support extensive field trials. AdRG1.3 adenovirus is formulated and packaged into baits by Artemis Technologies Inc. using proprietary technology. Field trials of AdRG1.3 rabies vaccine baits have been conducted in several Canadian provinces including Ontario, Quebec and New Brunswick. The results from field trials over the period 2006-2009 demonstrated superiority of the new vaccine over other licensed vaccines in immunizing wild animals that were previously difficult to vaccinate.