DOSE-RESPONSE OF CATS TO EXPERIMENTAL-INFECTION WITH FELINE VIRAL RHINOTRACHEITIS VIRUS

The clinical and virological aspects of the response of cats to intranasal infections with various doses of Feline Viral Rhinotracheitis (FVR) were studied. Cats inoculated with doses of 102, 103, 105, or 107 CCID50 of virus developed a characteristic upper respiratory syndrome whereas a dose of 101 CCID50 failed to establish an infection. Although individual variation in the response was quite marked, it was shown that an increase in the infecting viral dose was correlated with a decrease in the length of the incubation period before onset of pyrexia, other clinical signs and viral excretion. Although increasing viral dose appeared to be directly related to the severity of the clinical signs, this relationship was only found to be statistically significant for dyspnoea. There was some indication of an effect of an increase in infecting viral dose on the duration of the subsequent viral excretion. A significant relationship was found between the duration of viral excretion and the severity of the resultant syndrome. The serological responses of the cats to FVR were generally of low magnitude. The proportion of infected animals with neutralizing antibody titres rose from 6 of 15 (40 per cent) by PID 16 to 20, to 11 of 15 (73 per cent) by PID 30 to 34. © 1979.