Spectroscopic Studies of Infectious Pancreatic Necrosis Virus, Its Major Capsid Protein, and RNA

Infectious pancreatic necrosis virus (IPNV) causes the severe disease of salmonid fishes (trout, salmon, etc.) The IPNV virion consists of a double-stranded viral RNA surrounded by a protein capsid. The aim of the work is to determine the role of IPNV virion constituents (capsid proteins and viral RNA) in the formation of spectral properties of the whole IPNV virions. We have measured the UV-Vis absorption, fluorescence, fluorescence excitation, phosphorescence and phosphorescence excitation spectra of IPNV virions, major capsid protein (MCP), and viral RNA dissolved in different buffers. It is shown that the UV absorption of IPNV virions is caused by the absorption of both capsid proteins and viral RNA. The fluorescence of IPNV MCP and virions may be attributed to tyrosine and tyrosine + tryptophan, respectively. The low-temperature phosphorescence of virions can be attributed to that of capsid proteins, rather than viral RNA. The IPNV RNA phosphorescence spectrum exhibits the electronic-vibrational structure and may be due to the emission of adenine links.