Sequencing and characterization of the full-length gene encoding the single-stranded DNA binding protein of a novel Chelonian herpesvirus

Through 4 consecutive genomic walks employing a recently modified inverse polymerase chain reaction technique, a 4,054-bp DNA fragment of a newfound green turtle herpesvirus (GTHV) was obtained from tumor tissues of a green turtle with fibropapillomas. This newly identified viral DNA fragment contains two non-overlapping open reading frames (ORF) oriented in the 3′ to 5′ direction. The first ORF is 59% G+C rich and contains the full-length genomic sequence of the DNA binding protein (DBP) gene (3,585 bp) encoding a protein of 1,195 amino acid residues in length. The second ORF encodes a partial peptide of the UL28 gene. Phylogenetic analysis of the GTHV DBP gene confirmed and substantiated that this novel Chelonian herpesvirus is closely related to the subfamily Alphaherpesvirinae. Examination of the translated amino acid sequence further supports this categorization since GTHV DBP comprises a highly conserved zinc finger motif (CXLCX4RX2C) and a putative DNA binding domain, and exhibits high sequence homology to other alphaherpesviruses. Cloning and sequencing the genome of this putative herpesvirus will facilitate current understanding of its role in causing GTFP and the development of molecular- and immuno-based methods for the diagnosis and prevention of this devastating disease of green turtles.