Bovine herpesvirus 4 glycoprotein B is indispensable for lytic replication and irreplaceable by VSVg

The results show, however, that none of these soluble forms are able to block viral infectivity. To better understand the role of gB during BoHV-4 lytic replication, a recombinant BoHV-4 was generated by homologous recombination from a BoHV-4 cloned as a Bacterial artificial chromosome (BAC) (pBAC-BoHV-4-A), in which most of the BoHV-4 gB ORF was substituted by the insertion of a DNA stuffer selectable cassette. The resulting recombinant BoHV-4 genome (pBAC-BoHV-4-AΔgB-KanaGalK) was completely unable to reconstitute infectious replicating viral particles (Infectious Replicating Viral Particles, IRVPs) and to replicate when transfected in permissive cell lines in comparison to its revertant clone (pBAC-BoHV-4-ΔgB-Rev) or pBAC-BoHV-4-A parental clone.This demonstrates that the BoHV-4 replicating cycle is dependent on gB. Moreover, when gB was deleted from a recombinant BoHV-4 genome delivering an heterologous glycoprotein, Vesicular Stomatitis Virus Glycoprotein (VSVg), VSVg was unable to complement gB. This study provides direct evidence that gB is necessary for BoHV-4 lytic replication.The Herpesvirus envelope contains a variable number of glycoproteins involved in virus attachment, penetration, budding and spreading among infected cells. Some of these proteins are extremely conserved in functions and sequences, while others are typical of a peculiar virus genus or species.The entry model mechanism of Human Herpes Virus 1 (HHV-1) is based firstly on the interaction between glycoproteins gC and gB and the host cell heparan sulfates associated with glycosaminoglycans (GAGs) and secondly, by gD-mediated penetration that is also responsible for the fusion via gB, gH and gL [1]. Five glycoproteins are conserved in all herpesviruses, gB, gH, gL, gM and gN, and numerous studies have been carried out in order to characterize them [2].The gB gene is one of the most conserved glycoproteins among the herpesvirus family. Homologues of gB have in fact been identified in every hu