Homologous and heterologous interference requires bovine herpesvirus-1 glycoprotein D at the cell surface during virus entry

Expression of glycoprotein D (gD) of alphaherpesviruses protects cells from superinfection by homologous and heterologous viruses by a mechanism terme d interference. We recently showed that MDBK cells expressing bovine herpes virus (BHV)-1gD (MDBKgD) resist BHV-1, pseudorabies virus (PRV) and herpes simplex virus-1 (HSV-1) but not the more closely related BHV-5 infection as determined by the number of plaques produced. However, the plaque size is reduced in all four viral infections suggesting a block in cell-to-cell tra nsmission. Here, we show that MDBK cells expressing truncated BHV-1 go, des ignated MDBKt-gD, secreted soluble go and were fully susceptible to infecti on by all the four viruses when the cells were washed prior to infection. W hen MDBK cells or MDBKt-gD cells were treated with medium containing trunca ted go prior to infection, they partially resisted BHV-1, PRV and HSV-1 but not BHV-5. Interestingly, both BHV-1 and BHV-5 formed normal-sized plaques in MDBKt-gD cells suggesting that the viruses were able to spread efficien tly. Thus BHV-1 go is required at the cell surface at the time of infection in order to block BHV-1, HSV-1 and PRV infections, consistent with a commo n coreceptor for the three gDs.