Genetic relationships between bovine herpesvirus 4 and the gammaherpesviruses Epstein-Barr virus and herpesvirus saimiri.

The overall arrangement of genes in the unique central part of the bovine herpesvirus type 4 (BHV-4) genome has been deduced by analysis of short DNA sequences. Twenty-three genes conserved in at least one of the completely sequenced herpesviruses have been identified and localized. All of these genes encoded amino acid sequences with higher similarity to proteins of the gammaherpesviruses Epstein-Barr virus (EBV) and herpesvirus saimiri (HVS) than to the homologous products of the alphaherpesviruses varicella-zoster virus and herpes simplex virus type 1 or the betaherpesvirus human cytomegalovirus. The genome organization of BHV-4 had also an overall colinearity with that of the gammaherpesviruses EBV and HVS. Furthermore, the BHV-4 genes content and arrangement were more similar to those of HVS than to those of EBV, suggesting that BHV-4 and HVS are evolutionarily more closely related to each other than either are to EBV. BHV-4 DNA sequences were generally deficient in CpG dinucleotide. This CpG deficiency is characteristic of gammaherpesvirus genomes and suggests that the BHV-4 latent genome is extensively methylated. Despite several biological features similar to those of betaherpesviruses, BHV-4 displays the molecular characteristics of the representative members of the gammaherpesvirinae subfamily.