Virions proteins of an RSIV-type megalocytivirus from spotted knifejaw Oplegnathus punctatus (SKIV-ZJ07).

Megalocytiviruses have three main genotypes, which are represented by ISKNV, RSIV, and TRBIV. To date, the virion-associated proteins of RSIV and TRBIV are still unknown. The spotted knifejaw iridovirus (SKIV) is a newly characterized RSIV-type megalocytivirus. In this study, the virion-associated proteins of SKIV were identified by systemic one-dimensional gel electrophoresis-based proteomic approaches. A total of 49 viral proteins and 33 cellular proteins were associated with the SKIV virions by LC MS/MS, including 18 highly abundant structural proteins that were detected by MALDI TOF/TOF-MS. One highly abundant structural protein of interest was identified as the virus-inducible stress protein (VISP) and further characterized as an envelope protein. However, knockdown of mVISP by siRNA method showed no effect in virion production. The current study is the first to present detailed information on the virion-associated proteins of an RSIV-type megalocytivirus and to identify a novel cellular envelope protein of this virus.