| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2005: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2004: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
Betanodaviruses are the causative agents of a highly destructive disease of hatchery-reared larvae and juveniles of a variety of marine fish. The viruses can be classified into four types (SJNNV,BFNNV,TPNNV,RGNNV) based on similarities in the partial viral RNA sequences. This project seeks to identify a putative betanodavirus receptor that the viruses need to enter into host cells. It is postulated that a viral receptor that is displayed on the surface of a host cell should interact with the virion surface comprised of the coat proteins (CPs). Thus, we screened RGNNV CP-interacting proteins from the cultured fish cells (E-11 cells) using Yeast Two-Hybrid System and obtained three receptor candidates, designated CPIP5,CPIP41, and CPIP320. According to BlastP searches for CPIP5,CPIP41, and CPIP320 homologs against the Gen Bank database, the candidates were homologous to three kinds of proteins involved in defense systems of hosts. Interactions of these candidate proteins with the CP may lead to prevention of defense systems in hosts. These features are unique as compared with those of known viral receptors. Therefore, to evaluate the biological importance of CPIP5,CPIP41, and CPIP320, we tested binding ability of these proteins with SJNNV and BFNNV CPs as well as RGNNV CP. The three proteins interacted with all the CPs tested and are suggested to play important roles in betanodavirus infections of host fish. Furthermore, CPIP5 and RGNNV CP were co-localized in the nuclei of infected E-11 cells. These results indicate that CPIP5 and RGNNV CP interact with each other and play some roles in the nucleus to promote viral infections. More experiments are required to confirm that all or some of the candidates are components of a viral receptor even though the proteins are biologically important.
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