Dr. Sagar Goyal of the University of Minnesota has made progress in developing live attenuated vaccines to protect flocks from turkey reoviral arthritis (TARV) and hepatitis (THRV).
Six different vaccines were prepared using three strains of field isolates of reovirus. Candidate vaccine viruses were subjected to either serial passage or cold adaptation. The attenuated vaccines did not induce clinical changes confirming safety. There was apparently no stimulation of measurable systemic antibody. Challenge with field strains of TARV indicated that protection was inadequate based on histopathologic examination of tendons.
Dr. Goyal suggests that although a single vaccine administered at 10 days provided inadequate protection, multiple doses of vaccine may be required. Further studies are in progress to evaluate alternative frequencies and routes of vaccination. Ultimately protection will be possible from the sequence of primary stimulation with one or more attenuated products followed by a subsequent inactivated booster vaccine to establish maternal antibody transfer for breeder hens.