Biologics that Inhibiting White Spot Syndrome Virus and Their Application in Shrimp Farming

Abstract

The shrimp farming industry and related entities did not only have great economic value but also make a huge social impact in many developing countries. However, the World Bank estimated that the epidemic of several shrimp-related viral diseases that arose in the 1990s has resulted in an annual global loss, direct and indirect, of around US$3 billion. The white spot syndrome virus (WSSV) causes the most devastating disease for farmed shrimps around the world. Taiwan was once recognized as “the tiger prawn kingdom,” with a peak annual production of nearly 95,000 metric tons (MT). Production had dipped to 624 MT by 2012, with the harvest mostly dependent on polyculture with fish. The shrimp farming industry in Taiwan has been at the brink of total collapse since then. Transcending Biotechnologies, Inc. (TBI) is a biotechnology company registered in the US (est. in 2001) with expertise in antibody engineering and recombinant protein production. TBI has developed several biologics (including AP-1 and its improved secondary generation, AP-2) that have been demonstrated to inhibit the infectivity of WSSV in the laboratory. After the efficacy of AP-1 was confirmed by Dr. Lightner’s laboratory at the University of Arizona, TBI decided—mainly due to the Texas Law prohibiting farming tiger prawns for domestic shrimp species protection—to establish a subsidiary company, Taiwan Leading Biotech, Inc. (TLB; est. in 2005), in Taiwan to continue the development of AP-1. TLB’s immediate focus then was on the field tests for hatchery and grow-out culture of tiger prawn (Penaeus monodon) and greasyback shrimp (Marsupenaeus ensis) to prove that AP-1-treated fries were WSSV-free and could grow to marketable sizes. From 2005 to 2011, TLB had several key breakthroughs in the field tests involving AP-1 hatchery treatment procedures, improved shrimp fry feeds, and grow-out farming methods. At the TLB field test site, several batches of AP-1- treated tiger prawn were harvested at average size larger than 30g per shrimp, while most of the untreated prawns died in the early culture stage. Since 2008, TLB agreed to extend the field tests and joined a multiple-site testing program launched by the Center of Excellence for the Oceans (also known as the Center of Marine Bioscience and Biotechnology) of National Taiwan Ocean University in collaboration with National Taiwan University, to evaluate whether or not AP-1 treated P. monodon fry could grow at different locations in Taiwan and in various kinds of culture ponds. The data collected from several years of tests demonstrated that vertically transmitted WSSV could be effectively prevented by AP-1. All batches of shrimp fry were free of the disease during the first 60 days after stocking in culture ponds. However, some farming sites with poor environments and management have failed harvests due to various diseases. The data clearly indicated that AP-1 could significantly decrease the amount of WSSV in broodstock and fry (preventing the vertically transmitted disease), thus greatly improving the quality of shrimp fry. The prevention of WSSV transmission in the environment (horizontal transmission) is currently under study, as well as efforts to lower AP-1 production cost so that it can be applied in feeds.