The thymidylate synthase gene of Hz-1 virus: A gene captured from its lepidopteran host

The sequence analysis of a thymidylate synthase gene was identified in the Hz-1 virus HindIII-D fragment. The viral thymidylate synthase gene encodes a protein of 295 amino acids, and is closely related to that of insect, mam mals and herpesvirus. The thymidylate synthase gene identified was a genuin e viral gene in that it was only detected in cells infected with Hz-1 virus but not in the mock infected cells, by Southern blot analysis and by RT-PC R. Results of phylogenetic analysis based on non-synonymous and amino acid distances suggested that the TS gene of Hz-1 virus was grouped closely with that of Bombyx mori. High bootstrap values confirmed that the thymidylate synthase of Hz-1 virus was acquired by a capture event from its lepidoptera n host. Results of both sequence divergences and phylogenetic analysis sugg ested that TS genes in insect viruses, Hz-1, CIV, and MsEPV may have a diff erent history or originated from different capture events.