Detection and Co-interaction of White Sport Syndrome Virus (WSSV) and Laem-Singh Virus (LSNV) in Black Tiger Shrimp

Objective: Black tiger shrimp, Peneaus monodon is important in aquaculture sector in Thailand. White spot syndrome virus (WSSV) has caused great losses to the global shrimp industry. In 2005, the Laem-Singh virus (LSNV) was first reported in Thailand, which is associated with monodon slow growth syndrome (MSGS). In a primary observation we found that infected shrimps with Laem Sing virus could be also infected with WSSV. This study was aimed to detect WSSV and LSNV in shrimps and to determine the co-interaction between them. Method & Materials: A total of 70 samples were randomly collected from black tiger shrimp farms in November 2007 to May 2008. Those samples consisted of 48 samples in the Eastern Thailand and 22 samples from another area and were detected WSSV and LSNV using Ezee-Gene Nested PCR commercial kit (SBBU, Thailand). Results & Conclusion: The result showed that 36 out of 70 samples (51.43%) were WSSV positive, while 28 out of 70 samples (40.00%) showed LSNV positive. Interestingly, the samples of severe WSSV infection also showed severe LSNV infection at 57.15% (16 out of 28 LSNV infected samples), whereas the negative WSSV samples showed light LSNV infection. Nevertheless, there was no sign of disease associated with the presence of severe LSNV and WSSV infection. Our study demonstrated the evidence of disease caused by WSSV infection had co-interacted to LSNV infection. It is possibly that there was indirect association such occur, but it remains open the question of the disease transmission. The best way is that farmers should maintain the environment factors, which affected to shrimps physiology in cultured system and also frequently monitor during culture to protect disease outbreak.