Equine herpesvirus type 1 (EHV-1) replication in primary murine neurons culture

Equine herpesvirus-1 (EHV-1) infections cause significant economic losses for equine industries worldwide as a result of abortion, respiratory illness, and neurologic disease in all breeds of horses. The occurrence of abortions caused by EHV-1 has repeatedly been confirmed in Poland, but neurological manifestations of the infection have not been described yet. Also it is unknown how the infection of neurons with non-neuropathogenic strains is regulated. To further understand the virus-neuron interaction we studied two strains of EHV-1 in murine primary neuron cell cultures. Both strains were isolated from aborted fetuses: Rac-H, a reference strain isolated by Woyciechowska in 1959 (Woyciechowska 1960) and Jan-E isolated by Bańbura et al. (Bańbura et al. 2000). Upon infection of primary murine neuronal cell cultures with Jan-E or Rac-H strains, a cytopathic effect was observed, manifested by a changed morphology and disintegration of the cell monolayer. Positive results of immunofluorescence, nPCR and real-time PCR tests indicated high virus concentration in neurons, meaning that both EHV-1 strains were likely to replicate in mouse neurons in vitro without the need for adaptation. Moreover, we demonstrated that some neurons may survive (limited) virus replication during primary infection, and these neurons (eight weeks p.i.) harbour EHV-1 and were still able to transmit infection to other cells.