OIE《水生动物疫病诊断手册》病毒性脑病和视网膜病 2018版 第2.3.12章只用条款4.3.1.2.3.pdfVIP

C H A P T E R 1 . 1 . 1 . V I R A L E N C E P H A L O P A T H Y A N D R E T I N O P A T H Y 1. Scope1 For the purpose of this chapter, viral encephalopathy and retinopathy (VER) otherwise known as viral nervous necrosis (VNN) is considered to be a serious disease of several marine fish species, characterised by significant losses associated to vacuolating lesions of the central nervous system and the retina. 2. Disease information 2.1. Agent factors 2.1.1. Aetiological agent, agent strains The causative agent of VER or VNN was first identified as a new member of the family Nodaviridae following purification of brain tissues from affected striped jack larval, and the name striped jack nervous necrosis virus (SJNNV) was adopted (Mori et al., 1992). Subsequently other agents of VER/VNN were purified from some diseased fish species (Chi et al., 2001; Comps et al., 1994). The current taxonomy classifies the viruses into the genus Betanodavirus within the family Nodaviridae (Schneemann et al., 2005). Betanodaviruses are non-enveloped, spherical and approximately 25 nm in diameter. The genome consists of two molecules of positive-sense ssRNA: RNA1 (3.1 kb) encodes the replicase (110 kDa) and RNA2 (1.4 kb) encodes the coat protein (42 kDa). Complete nucleotide sequences of RNA1 and RNA2 were reported for SJNNV and others (Iwamoto et al., 2001; Iwamoto et al., 2004; Sommerset Nerland, 2004; Tan et al., 2001). On the basis of the phylogenetic analysis of the T4 variable region of RNA1, betanodaviruses have been preliminarily clustered into four major ge