Cloning and Sequence Analysis of the Genome Unique Long Region of Pseudorabies Virus Ea Strain

A 3.76 kb genome DNA fragment, containing the complete coding sequences of UL31, UL32, UL33 and UL34 genes and the partial coding sequences of UL30 and UL35 genes of Pseudorabies virus (PRV) Ea strain, was amplified by PCR and sequenced. The results show that the G+C contents of UL31, UL32, UL33 and UL34 genes are varied from 69.5% to 73.4%, and the amino acid composition is skewed to codons rich in Gs and Cs nucleotides, especially the third codon is Cs or Gs. The three most common amino acids (Ala, Leu and Arg) comprise 36.4% of the total residues. Both the nucleotide and amino acid sequences identities of UL31 and UL32 genes of PRV Ea strain and PRV Ka strain are more than 98.2%, whereas the amino acid identities of UL33 and UL34 genes are 95.7% and 94.8%, respectively. The UL31 gene is highly conserved among alphaherpesviruses, and the homology of UL31 gene of PRV and Equine herpesvirus 4 (EHV-4) is higher than others. The amino acid sequence identitie of UL32, UL33 and UL34 genes of PRV and Bovine herpesvirus 1 (BHV-1) are higher than others. Protein kinase C phosphorylation sites and casein kinase II phosphorylation sites are found in all the amino acid sequences of UL31, UL32, UL33 and UL34 genes, which suggests that all the four genes are possibly phosphoproteins.