38th Annual Meeting of the Society for Invertebrate Pathology

The eukaryotic enzyme, poly(A) polymerase catalyzes addition of adenosine (A) residues to the 3’ end of mRNA. All viruses of the Poxviridae family, including the entomopoxvirus from Amsacta moorei, (AMEV) transcribe mRNAs in the cytoplasm from the viral DNA template. The viral cytoplasmic transcriptional apparatus includes a poly(A) polymerase. The poly(A) polymerase from vaccinia virus (VV), is a heterodimer consisting of a large subunit (E1) and a small subunit (J3). The multifunctional J3 subunit confers processivity to the poly(A) addition initiated by the E1 subunit resulting in longer poly(A) tails. J3 also possesses 2’O-methyltransferase activity and functions as a positive transcription elongation factor. Unlike VV, AMEV encodes two small subunits, AMEV060 and AMEV115 both with similarity to VV J3. AMEV060, like VV J3 is expressed early, prior to DNA replication, whereas AMEV115 is expressed as a late gene. We show that AMEV060, like J3 possesses 2’O-methyltransferase activity. Surprisingly, AMEV060 can be deleted without effects on virus growth in cell culture. Experiments are underway to attempt deletion of AMEV115. The effects of deleting the small subunit genes on mRNA synthesis and mRNA poly(A) addition is being evaluated. Interactions of each AMEV small subunit with the large subunit are being explored.