Equine rhinitis A virus: structural proteins and immune response

Equine rhinitis A virus (ERAV) is a picornavirus that has been reclassified as a member of the Aphthovirus genus because of its resemblance to foot-an d-mouth disease virus at the level of nucleotide sequence and overall genom ic structure. The N-terminal amino acid sequence of three of the four capsi d proteins of ERAV was determined and showed that the proteolytic cleavage sites within the precursor P1 polypeptide occur exactly as those predicted for an aphthovirus-like 3C protease, which generates the capsid proteins VP 1 and VP3. However, the autocatalytic cleavage site between VP4 and VP2, wh ich is independent of 3C protease cleavage, was different from that predict ed previously. ERAV.393/76 antisera from horses and rabbits showed differen t reactivity to the viral structural proteins in both serum neutralization assays and Western blots. High neutralizing antibody titres appeared to cor relate with strong reactivity to VP1 in Western blots.