Sensitivity of bovid herpesvirus 2 replication to temperatures found in the natural host

Two isolates of bovid herpesvirus 2 replicated poorly in bovine testicular cells and fetal kidney cells at 39--40 degrees C, temperatures commonly observed in virus-infected cattle. High viral titers occurred in replicate cultures at 30--37 degrees C. Persistent viral infections were noted in cultures maintained at 40 degrees C. Interferon-like activity was not responsible for the high-temperature restriction since the level was not significantly different between virus-infected cultures incubated at 35 degrees or 40 degrees C. Spontaneous viral inactivation was only three times as rapid at 41 degrees as at 35 degrees C. Analysis of temperature shift experiments with respect to results of growth studies and electron microscopy indicated a temperature sensitive event late in replication. The sensitivity of bovid herpesvirus 2 replication to elevated temperature provides a possible explanation for the extensive viral growth and occasionally severe lesions which are limited exclusively to the skin of infected cattle.