A recombinant Semliki Forest virus particle vaccine encoding the prME and NSl proteins of louping ill virus is effective in a sheep challenge model

This study has examined the efficacy following intramuscular administration of a recombinant Semliki Forest Virus (rSFV) vaccine, encoding the prME an d NS1 proteins of louping ill virus (LIV), in sheep. Administration of rSFV -LIV vaccine resulted in transient detection at the injection site and drai ning lymph node only and no dissemination to distal sites. In addition, the recombinant vaccine offered complete protection against subcutaneous chall enge with LIV, and partial protection following intranasal administration o f LIV. Protected animals had no pathological changes normally associated wi th LIV infection, and had developed high antibody titres. In contrast, the two animals not protected exhibited classical clinical signs and neuropatho logical lesions of LIV infection. These findings indicate that rSFV-based v accines have the potential to be developed as effective prototype vaccines for LIV. (C) 2001 Elsevier Science Ltd. All rights reserved.