Double-stranded RNA treatment for SPF shrimp stocks of a newly discovered viral infection

Using post-larvae derived from specific pathogen free (SPF) stocks in penaeid shrimp farming has led to a dramatic increase in production. At the same time, new pathogens of farmed shrimp are continually being discovered. Once a new shrimp viral pathogen is discovered, the stock must be checked for freedom of that pathogen even if it has never shown any gross signs of that disease. If the SPF stock is found to be positive for the newly discovered pathogen, serious problems can arise. The stock developers are faced with destroying their existing stock which has been developed over a long period at considerable cost and starting the whole stock development process anew with the newly discovered pathogen added to the SPF list. An alternative option requiring less time and cost is in need.

SPF shrimp

Researchers hypothesized that injection of complementary double-stranded RNA (dsRNA) into viral-infected broodstock prior to mating might inhibit replication of the target virus sufficiently to reduce or eliminate its transmission to their offspring. Subsequent selection of uninfected offspring would allow for post-clearing of the new virus from the existing stock and for conversion of the stock free of the new virus. This hypothesis was tested using the stock infected with Laem Singh virus (LSNV). The transmission was substantially reduced in several treated broodstock compared to much higher transmission in buffer-injected broodstock. Based on these results, the model is proposed for post-clearing of SPF stocks using dsRNA treatment. The model may also be applicable to post-clearing of exceptional, individual performers from grow-out ponds for return to a nucleus breeding center.

This study was a collaborative effort between the Shrimp Molecular Biology and Biotechnology Laboratory, Center of Excellence for Shrimp Molecular Biology and Biotechnology and Mahidol University.

Ref.: Saksmerprome V, Charoonnart P, Flegel TW. (2017) Feasibility of dsRNA treatment for post-clearing SPF shrimp stocks of newly discovered viral infections using Laem Singh virus (LSNV) as a model. Virus Research, 235, 73–76.

 

Posted on 19 April 2018.