Infectious bovine rhinotracheitis virus. History and recent developments.

The infectious bovine rhinotracheitis (IBR) virus belongs to the group of herpes viruses. It causes in cattle a severe disease predominantly in the upper respiratory tract. Morbidity rate is 100 percent, mortality - depending on hygienic and other factors - ranges from 0-15 percent. The IBR virus is serologically indistinguishable from the infect pustulat vulvovaginitis (IPV) virus which causes disorders of the genital tract in both male and female cattle. Possibly the IPV virus is the older of the two. Already in the twenties it had been isolated and described in Europe whereas IBR virus was first isolated from feedlot cattle in the USA during 1955/1956. Most likely - experiments also gave a hint - the IPV virus increased its virulence for the respiratory tract by rapid and numerous passages as this was only possible in accumulations of tremendous heads of animals. Vaccines both live attenuated and killed ones have been developed. Killed ones are always administered parenterally; the live ones are either intramuscularly injected or locally sprayed (into the nasal cavity). Immunity is developed within 3 weeks, however, if vaccinated animals are challenged, virus is again shed for a number of days. Cattle thereby do not exhibit any symptoms of disease. This is true following any kind of vaccination (live or killed). After local administration of live vaccines, however, the production of interferon by the cells of the respiratory tract is remarkable whereas parenterally administration of vaccine does not lead to that.