Pathogenesis of acute and persistent murine herpesvirus infection in mice.

Outbred laboratory mice were inoculated at the age of 5, 10 and 21 days by oral and/or intranasal routes with 2 different (a lethal and a nonlethal) doses of the murine herpesvirus isolate 68 (MHV-68). Severe exudative pneumonia with haematogenous dissemination of the virus to liver, heart muscle, and kidneys developed in the 5-day-old as well as in a part of the 10-day-old mice. Virus antigen was found by immunofluorescence (IF) in the alveolar lining of lungs, in heart muscle fibres, in spleen and thymic lymphocytes, in the tubular epithelium cells of kidneys, in the neurons of Gasserian ganglia and in the intima of large pulmonary vessels. Electron microscopy confirmed the transfer of virus particles through the capillary endothelium of the damaged alveolar septa. The surviving progeny and the mothers of animals, which had not succumbed to the lethal virus dose, were kept for 141-169 days when lungs and Gasserian ganglia were examined for virus presence. MHV-68 was recovered both by direct examination of the tissue homogenates as well as by the explantation technique. The results are suggestive for a dynamic persistence of MHV-68 rather than for static latency.