IN-SITU STUDY ON THE PATHOGENESIS AND IMMUNE-REACTION OF EQUINE HERPESVIRUS TYPE-1 (EHV-1) INFECTIONS IN MICE

The mouse model was used to study the pathogenesis of equine herpesvir us type 1 (EHV-1) after primary and secondary intranasal infections. W ithin a few hours after infection, EHV-1 was found in nasal and olfact orial epithelium and sub-epithelial cells of the respiratory mucosa, b ut antigen-specific immune cells were never detected. Next to the lung , EHV-1 was transmitted early and directly to the brain, both via the olfactory route and the trigeminal nerve, but traces of degenerative o r inflammatory processes were not detected there. In the lung, the imm une cells residing or invading the parenchyma did not contain viral DN A or proteins. The primary immune response in the lungs was an alveola r and interstitial inflammation, dominated by the sequential appearanc e of neutrophils and macrophages. while the number of T and B lymphocy tes remained unaltered, Within 24 hr after re-infection, lymphocytes a ccumulated around the blood vessels, outnumbering monocytes more than twofold, without neutrophils appearing. The lymphocytes comprised of l ittle more B than T cells and the T cells were predominantly CD8(+) ce lls. Those and B cells infiltrated the parenchyma. These results show the route of virus distribution and demonstrate the lack of antigen-sp ecific immune cells in the lungs of mice after primary intranasal infe ction with EHV-1.