Role of the UL28 homologue of bovine herpesvirus 1 in viral DNA cleavage and packaging.
In the aim to study the function of the bovine herpesvirus 1 (BoHV-1) UL28 protein during the replicative cycle, we characterized a UL28 deletion mutant of BoHV-1, BoHV-1 Delta UL28. Productive growth of BoHV-1 Delta UL28 was only observed in a specifically engineered complementing cell line expressing the native UL28 protein, demonstrating that UL28 is essential for virus replication. UL28 deficiency did not compromised viral protein synthesis of the late class as shown by the detection of the viral alpha gene trans-inducing factor protein encoded by UL48, a gene of the gamma2 class. Southern blotting analyses of total DNA extracted from BoHV-1 Delta UL28-infected normal cells revealed that viral DNA replication was not compromised but the process of cleavage of the newly synthesized DNA was defective. Transmission electron microscopy of non-complementing BoHV-1 Delta UL28-infected cells revealed an accumulation of capsids devoid of DNA, suggesting that the DNA packaging was impaired. We conclude that the BoHV-1 UL28 protein is essential for viral replication and is necessary for the formation of mature capsid.
Desloges
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Institut National de la Recherche Scientifique, Centre INRS-Institut Armand-Frappier, Laval, Québec, Canada. desloges@uni-wh.de
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D000818:Animals; D002213:Capsid / Q000648:ultrastructure; D002460:Cell Line; D004279:DNA, Viral / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D007242:Herpesvirus 1, Bovine / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D014764:Viral Proteins / Q000235:genetics / Q000502:physiology*; D014779:Virus Replication
D004279:DNA, Viral; D004268:DNA-Binding Proteins; D014764:Viral Proteins