Feline calicivirus protein synthesis investigated by western blotting.

We have used Western blotting to examine the accumulation of feline calicivirus proteins within the infected cell. Experiments using elevated growth temperature to block post-translational cleavage have demonstrated two additional high molecular weight protein bands 125 kd and 123 kd respectively which may be precursor polyproteins. Inhibition of proteolytic processing with p-fluorophenylalanine led to the accumulation of several additional protein species which may represent intermediates in the protein processing pathway. None of these proteins were related to the 62 kd major capsid protein (cP62) of the virus as judged by reaction with monoclonal antibodies. The production of a 76 kd capsid precursor protein (cpP 76) was demonstrated for the first time in FCV-infected cells. The pathway by which calicivirus polypeptides are made thus appears highly complex and may involve temporal regulation of protein synthesis as well as protein processing. Tentative identification of primary, intermediate and mature forms of virus proteins is discussed.