Replication of equine herpesvirus type 3: kinetics of infectious particle formation and virus nucleic acid synthesis.

The kinetics of equine herpesvirus type 3 (EHV-3) multiplication and of the synthesis of EHV-3 specific DNA and RNA were investigated. A one-step growth curve of EHV-3 in equine epithelial cells from a transitional cell carcinoma was characterized by: (1) a short eclipse period (4 h); (2) an exponential increase in infectious virus between 5 and 10 h post-inoculation; and (3) a slow, inefficient release of newly formed virus into the extracellular fluid. Two hours after infection of cells with EHV-3, the rates of incorporation of specific precursors into total cell RNA or DNA were reduced to 30% and 10%, respectively, of that seen in uninfected cells. With the aid of DNA-RNA hybridization and caesium chloride isopycnic centrifugation techniques, the rates of synthesis of EHV-3 specific nucleic acids at different stages of the virus replication cycle were determined. Virus RNA and DNA synthesis was detectable 2 h after infection and reached maximum levels at an interval (4 to 7 h post-inoculation) corresponding to that period of the virus replication cycle just preceding the time of maximal synthesis of infectious virus.