Analysis of cyclins in trigeminal ganglia of calves infected with bovine herpesvirus-1

Following acute infection of cattle with bovine herpesvirus-1 (BHV-1), cycl in expression was examined in trigeminal ganglia (TG). Cyclin A was primari ly detected in the nucleus of TG neurons. In contrast, cyclin D1 and cyclin E were detected in the nucleus and cytoplasm of TG neurons. Uninfected or latently infected calves did not express detectable levels of these cyclins in TG neurons. Following dexamethasone-induced reactivation, cyclins D1, E and A were also detected in TG neurons. In situ hybridization of consecuti ve sections demonstrated that many neurons expressing cyclins contained vir al nucleic acid, demonstrating that they were infected. Based on these obse rvations, we hypothesize that BHV-1 infection activates neuronal cyclin exp ression to enhance productive infection. It is also possible that the stres s of neuronal infection or reactivation leads to cyclin expression.