The Study of Persistent Infection with Piscine Nodavirus

• Main Authors: Cheng Tsun-Ming, 鄭存明
• Other Authors: Chi Shao-Chi
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/14111340443668439465

碩士 === 國立臺灣大學 === 動物學研究所 === 89 === Viral nervous necrosis disease, VNN disease, is one of the most important marine diseases affecting finfish. Nervous necrosis virus, NNV, which belongs to Nodaviridae is the causative agent of VNN disease. This study was focused on persistent infection with NNV. The results suggested that groupers (Epinephelus sp.) surviving VNN outbreak could be persistently infected by nodavirus. Infectious NNV particles were released via feces by these carrier groupers. Carrier groupers are therefore a possible reservoir of NNV. NNV was located in various tissues, including nervous tissues and many visceral organs. Death could be induced among carrier groupers by superinfection with NNV. Progression of VNN disease was described. NNV persistently infected cell line (BB cell line) was established. BB cell line released low levels of NNV detectable at each subculture. Experiments were performed to characterize the nature of persistent infection in BB cell line, and the possible mechanisms of maintenance of persistent infection were discussed. Infectious virus was detected in BB cell culture supernatant, and the titers of different subcultures fluctuated below 106 TCID50/0.1 ml. NNV coat protein gene was detected in BB cell line by RT-PCR. NNV antigens could be found in small portion of BB cells by immunostain using GNNV-specific antiserum. Viral persistence in BB cells was not affected by shifting incubation temperature, so temperature and temperature sensitive virus mutants are probably not involved. BBNNV, NNV isolated from BB cell line, had unique variation in coat protein gene when compared with other strains of piscine nodavirus. The difference of antigenicity of BBNNV from GNNV was shown by ELISA using GNNV-specific monoclonal antibodies. This characteristic was a candidate for further investigation of persistent infection.