Characterization of herpesvirus of turkeys. Replication using recombinant DNA

DNA has been isolated from herpesvirus of turkeys (HVT) virions and used to construct a partial gene library in pBR-322. The recombinants have been characterized and shown to contain HVT DNA inserts. A representative recombinant containing a 5.9-kilobase HindIII fragment was used as a probe to quantitate the yields of HVT DNA in vitro and to follow the kinetics of viral DNA replication. The data shown that in chicken fibroblasts, viral DNA synthesis initiates by about 12-14 hr postinfection and that the yield of progeny virus plateaus at 28-30 hr postinfection. Based upon quantitative hybridization to cloned DNA probes, we estimate that approximately 2000 HVT genomes are produced per infected cell in vitro; however, in vivo in persistently infected turkeys, the number of viral genomes was below the level of detection by Southern blotting.