COMPARISON OF DNA APPLICATION METHODS TO REDUCE BRSV SHEDDING IN CATTLE

We compared the protection afforded by three different DNA application methods against bovine respiratory syncytial virus (BRSV) infection i n cattle. A synthetic gene that codes for the G protein of BRSV was in serted into a eukaryotic vector and was used in the vaccine. Intraderm al (i.d.) application with a needleless injector (NI), the pigjet(TM) reduced BRSV excretion significantly better after BRSV challenge than intra-muscular (i.m.) or i.d. vaccination with a needle, Serum antibod ies against the G protein were consistently the highest and showed les s variation in calves vaccinated with the NI compared with those in i. m. and i.d. vaccinated calves. After BRSV challenge, secondary serum a nd mucosal antibody responses were also the highest in NI vaccinated c alves. We conclude that DNA application with the needleless injector i s substantially better than im. or i.d. application and is capable to prime the immune response at the respiratory mucosa, (C) 1997 Elsevier Science Ltd All rights reserved.