RAPID DIAGNOSIS AND INFECTION STATUS OF WSSV, AHPND AND EHP DISEASES IN POST LARVAE AND FARM REARED Penaeus vannamei BY INSULATED ISOTHERMAL PCR METHOD

Introduction

Aquaculture production is increased every year due to compensate the global food demand. Because of the intensive aquaculture practices, new diseases are emerged as well as increase the virulence of existing pathogen due to the stressful and crowded condition. Shrimp farmers wants to diagnose the post larvae and farm reared shrimp quickly before stocking. Hence, the insulated isothermal PCR method is an alternate techniques suitable to diagnose the shrimp disease in accurate and quickly to fulfill the farmers need.  

Materials and methods

Shrimp post larvae and farm reared P. vannamei shrimps were collected from hatcheries located in the East Coast of TamilNadu and farms located in the maritime districts of TamilNadu. Shrimps tissues were aseptically collected and DNA was isolated as per the manufacturer instruction (Genetics, Taiwan). One ul  of DNA was transferred to the PCR premix specific to each disease and placed in the PCR machine to run for 35 minutes. The result was confirmed (+) or (-) on the PCR display after completion of the reaction.

Results and Discussion

The WSSV, AHPND and EHP infection percentage were measured from April 2016 to March 2017 from the East Coast hatcheries and farm samples total of 186 from TamilNadu states. Among that, the highest infection percentage of WSSV was found to be 66% during the month of February 2017 and the percentage of EHP infection was 62% during the month of June 2016. The WSSV infection rate was higher during the month of February due to the low temperature which depress the immune system of the shrimp (Gunalan et al., 2010). The EHP infection was gradually reduced during the year of 2017 because the hatchery owners fed the brooders by cultured polychaete worms instead of wild collection.

Conclusion:

Specific pathogen free (SPF) shrimp seeds are sometimes exposed with dreadful diseases because of the improper maintenance. The insulated isothermal PCR is highly useful to the farmers to diagnose the shrimp PL and farm reared animal within an hour.