Development of new PCR primers for detection of Koi Herpes Virus (KHV)

Abstract

Outbreaks of a new disease responsible for mass mortality in common carp (Cyprinus carpio) and koi carp (Cyprinus carpio koi) may have occurred as early as 1996 (Haenen et al., 2004). First scientific report on the disease appeared in 1998 and the disease-causing agent was termed as koi herpes virus (KHV). Therefore, this virus was first reported as the cause of mass mortality among koi carps from Germany, Israel and USA in 1998 (Bretzinger et al., 1999; Hedrick et al., 2000). Since then, outbreaks of KHV disease have been regularly reported from Europe, South Africa, USA and Asia. In Asia, KHV has been reported from Israel, Indonesia, Taiwan, China (Hong Kong), Thailand, Japan and Malaysia. KHV is also called as carp interstitial nephritis and gill necrosis virus or cyprinid herpesvirus-3. The disease is temperature dependent, occurring at water temperatures between 16-25 °C. The disease causes severe financial losses and the mortality rates have consistently been more than 80% in affected populations. The genome of KHV is a double stranded DNA sequence of 295 kbp belonging to family of Alloherpesviridae. Entire genome sequencing of three KHV strains from Japan, USA and Israel has been completed (Aoki et al., 2007). Molecular methods such as DNA hybridization, polymerase chain reaction (PCR) and enzyme linked immunosorbent assay have been used for detection of KHV in fish (Gray et al., 2002; Bercovier et al., 2005; Adkison et al., 2005). The objective of the study was to design specific and sensitive PCR primers for detection of major capsid protein (MSP) gene of KHV in koi and common carps