CLEARANCE AND SHEDDING OF INFECTIOUS BOVINE-RHINOTRACHEITIS VIRUS FROM THE NASAL-MUCOSA OF IMMUNE AND NON-IMMUNE CALVES

  • 1 January 1980
    • journal article
    • research article
    • Vol. 41  (1) , 117-119
Abstract
Infectious bovine rhinotracheitis virus was rapidly cleared from nasal mucosa of calves after intranasal aerosol exposure. Non-immune calves (experiment 1) cleared 109 plaque-forming units (PFU) of virus from the nasal mucosa in less than 4 h and 106 PFU of virus in 1 h. An eclipse phase followed clearance of viral inoculum. Replicating virus was first detected at 9 h. Viral titers increased stepwise until maximum was attained on post-inoculation day 4. Virus persisted in the nasal mucus until day 12. Clinical signs of disease corresponded with shedding of virus. In contrast to non-immune calves, immune calves (experiment 2; same calves as in experiment 1, but 30 days after initial exposure) cleared 109 PFU of virus in 1 h and 106 PFU of virus in less than 5 min. An abortive reinfection occurred after exposure of immune calves with 109 PFU of virus. Virus was first detected in these calves 14 h after exposure and was not detected beyond 24 h after inoculation. Immune calves given 106 PFU of virus did not shed virus after clearance of inoculum. Clinical signs of infection were not observed in immune calves after viral challenge exposure. There apparently was no detectable residual virus beyond 3 h after exposure.