EXPERIMENTAL INOCULATION OF CATTLE WITH BOVINE HERPESVIRUS-4 - EVIDENCE FOR A LYMPHOID-ASSOCIATED PERSISTENT INFECTION

Abstract

A strain of bovine herpesvirus-4 isolated from cows with mammary pustular dermatitis was used for experimental inoculation of cattle. This strain is serologically indistinguishable from the group prototype Movar 33/63 and from strain DN-599. Seronegative cattle were inoculated or by simultaneous intranasal, i.v., intrammary (via teat channel) and intradermal inoculations. All inoculated cattle seroconverted. Clinical signs of disease or lesions were not evident, except for a dermal lesion corresponding with 1 intradermal inoculation site. Virus was recovered from the dermal lesion and was excreted in the milk for 17 days. Virus was recovered from esophagopharyngeal fluid at 9 and 13 days after inoculation. At different times of euthanasia (2-14 mo. after inoculation), virus was recovered from cocultures with bovine lung cells and/or explant cultures of lymph nodes, spleen, tonsils and, in 1 case, kidney. In 2 animals, the virus was recovered repeatedly during 1 yr from peripheral blood leukocytes by cocultivation with bovine lung cells. The number of infectious leukocytes, as determined by infectious center assay, ranged from < 1-6 infectious cells/107 leukocytes.