Study of Koi Herpesvirus Persistent Infection Mechanism

• Main Authors: Mu-Jung Tu, 杜牧融
• Other Authors: 陳媺玫
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/49153165328792509344

碩士 === 國立臺灣大學 === 獸醫學研究所 === 101 === Koi herpesvirus (KHV) infection cause severe financial losses. KHV is a member of Alloherpesviridae, and newly designated species Cyprinid herpesvirus 3. The virion have an outer envelope and an icosahedral capsid contains a single, linear, double-stranded DNA of 295 kbp. Common carp (Cyprinus carpio carpio) and Koi carp(Cyprinus carpio koi) are the only species known to be affected by KHV. The survivors will become carrier fishes, but persistent infection mechanism of KHV is not clear. One of the unique features of Herpesviridae is latency which had been confirmed in Channel catfish virus and Cyprinid herpesvirus infection model. KHV can become latent in the peripheral white blood cells and various tissues, and will reactivation while temperature shifting, or been forced. The aim of this study is trying to find out persistent infection mechanism of KHV. Persistent infection mechanism in tissue culture includes interferon, intranuclear episome, viral DNA insertion, or virus producing latency-associated transcripts. We established two KHV persistently infected cell lines from carrier fishes through primary cell culture. Persistent infection cells characteristics such as growth rate and chromosome analysis are different from healthy cells. These two cells do not accept superinfection of virus from aquatic sources. The virus titer of persistently infected cells is fluctuation, and have no ability to induce fish mortality. The results of in situ hybridization showed the KHV positive signals in gill and kidney. In this study, virus produced by the two persistently infected cells are compared to the wild KHV, such as virus titer and organ distribution. Current results showed that the mechanism of KHV persistent infection is relate to interferon releasing and virus genome insertion.