Contemporary methods of koi herpesvirus diagnostics [in cyprinid fish species]. [Doctoral dissertation] | Savremene metode dijagnostike Koi herpesviroze ciprinida. Doktorska disertacija

Herpesvirus infection can lead to major losses in carp aquaculture. Since 1999, when it was first isolated, a large number of methods for detection of koi herpesvirus are described. Given that the virus isolation is difficult, polymerase chain reaction (PCR) has proved to be an efficient tool for the detection of viral DNA in different organs of infected fish. At least 7 different PCR tests are used for diagnosis of KHV in laboratories worldwide. Better understanding of mechanisms involved in transmission of the virus and identification of species susceptible to KHV increase the sustainability of the production of carp and koi carp. It is important to determine whether KHV cause disease in other cyprinid and non-cyprinid fish species. In this dissertation an investigation of the sensitivity of different KHV detection methods, susceptibility of carp and other species on KHV infection and disease, the possibility koi herpesvirus infection without clinical symptoms and the possibility of influence of various factors on the spread of virus by asymptomatic carriers, was carried out. Our study confirmed that KHV could cause latent infection of KHV-infected fish without clinical symptoms, as well as the possibility of virus reactivation of the virus by stress and transmission of KHV to naive carp. In the study is found that the koi herpes virus has more hosts than is typical for herpesviruses and demonstrated susceptibility of tench, grass carp, prussian carp, goldfish and silver carp to KHV. All these species transferred KHV to naive carp. Comparison of different PCR methods showed a significant influence of primers and polymerase to the sensitivity of KHV PCR detection methods. It was found that the sensitivity of KHV LAMP with HNB is equal to KHV LAMP test with SYBR green. KHV LAMP test with the HNB has demonstrated several advantages over the LAMP test with SYBR green, and they are reflected primarily in reducing the risk of contamination due to the fact that the indicator is added before the reaction, and the ability to alleviate the assessment of positive-negative reactions found by naked eye, whereby the sensitivity of detection is equal to the test with SYBR green. The results of stress experiments showed that the stress has a significant role in spread of koi herpesvirus, in the reactivation of the virus as well as, often asymptomatic, appearance of virus excretion.