Incidence of Macrobrachium rosenbergii nodavirus (MrNV) in Thailand by using RT-nested PCR detection method

Objective: Macrobrachium rosenbergii is one of the most important and economically farmed prawn species in Thailand. The major farming areas are situated in the central Thailand, especially southwest of the ChaoPhaya River Basin. One of the major constraints for culturing this species is white tail disease (WTD), which caused by Macrobrachium rosenbergii nodavirus (MrNV).Occurrence of this disease in several countries such as Taiwan, French West Indies, China and India has been reported. We are interested in exploring the incidence of MrNV infection in giant freshwater prawn farms in the central Thailand. Method & Materials: A PCR test kit, titled Ezee-Gene MrNV RT-nested PCR (MrNV test kit), was developed to detect MrNV infections in freshwater prawns (Thai partial patent number 0803000211). This test kit has the ability to differentiate the level of MrNV infection i.e. severe, moderate and light infection, which is indicated by the number of bands on gel electrophoresis. A total of 131 prawns were randomly collected from hatcheries and ponds in central Thailand from September 2007 to July 2008 and checked for the MrNV infection using the above test kit. Results & Conclusion: Forty-nine samples (37.40%) were MrNV positive. This included 8 broodstock samples and 15 post-larvae that showed a light MrNV infection, whereas 26 juvenile samples had severe MrNV infection. There were no gross signs associated with WTD in both post-larvae and broodstock with light MrNV infection. However, only a few post-larvae with MrNV infection survive in grow out ponds.This study confirmed the incidence of MrNV disease outbreaks in the freshwater prawn farms in central Thailand. The information obtained from this study will be used to develop a quarantine method and to disseminate information on suitable farm management practices to farmers.

کلیدواژه ها:

Incidence ، MrNV ، giant freshwater prawn