rinderpest virus h protein role in determining host range in rabbits a major molecular determinant of virus hostrange is thought to be the viral protein required for cell attachment we used a recombinant strain of rinderpest virus rpv to examine the role of this protein in determining the ability of rpv to replicate in rabbits the recombinant was based on the rbok vaccine strain which is avirulent in rabbits carrying the haemagglutinin h protein gene from the lapinized rpv rpvl strain which is pathogenic in rabbits the recombinant virus rrpvlaph was rescued from a cdna of the rbok strain in which the h gene was replaced with that from the rpvl strain the recombinant grew at a rate equivalent to the rpvrbok parental virus in b95a cells but at a lower rate than rpvl the h gene swap did not affect the ability of the rbok virus to act as a vaccine to protect cattle against virulent rpv challenge rabbits inoculated with rpvl became feverish showed a decrease in body weight gain and leukopenia high virus titres and histopathological lesions in the lymphoid tissues were also observed clinical signs of infection were never observed in rabbits inoculated with either rpvrbok or with rrpvlaph however unlike rpvrbok both rpvl and rrpvlaph induced a marked antibody response in rabbits therefore the h protein plays an important role in allowing infection to occur in rabbits but other viral proteins are clearly required for full rpv pathogenicity to be manifest in this species