Virulence Factor In Aquaculture

Aquaculture is an important food-producing sector, and it provides much needed protein, employment, income and livelihood support to many people in the world (Bestha L 2013). Shrimp, in particular, is a high value commodity that is mainly produced in Asia, especially targeting for export purpose, and brings a wealth of revenue to many developing countries (N. Kalaimani 2013). However, the major problem faced by the aquaculture industry worldwide is diseases caused due to bacterial diseases and has been cited as the single largest source of economic loss in the aquaculture industry.

Of all the bacterial diseases vibriosis is considered to be one of the foremost disease in the shrimp aquaculture (Karunasagar, Sugumar et al. 1995). Vibriosis

Virulence factor toxin T1, responsible for the virulence of V. harveyi in Penaeus monodon under quorum sensing control (Manefield, Harris et al. 2000). Other phenotypes or virulence factors which were shown to be linked to the quorum sensing in Vibrio harveyi are siderophore production, type III secretion, chitinase production, polysaccharide production, metalloprotease, bioluminescence, cysteine protease caseinase, gelatinase, lipase, phospholipase and haemolysins production (Lilley and Bassler 2000; Manefield, Harris et al. 2000; Zhang 2000; Defoirdta, Boona et al. 2004; Henke and Bassler 2004; Defoirdt, Darshanee Ruwandeepika et al. 2010; Natrah, Defoirdt et al. 2011; Kalia 2013). Thus, given the importance of QS in virulence development, it is particularly interesting to target this pathway for preventing and managing vibriosis in the aquaculture

Antipathogenic drugs target key regulatory systems in bacterial pathogens that regulate the expression of virulence factors. The fact that antipathogenic compounds are unlikely to pose a selective pressure for the development of resistance towards them, makes this concept highly attractive as a sustainable biocontrol strategy (Rasmussen and Givskov 2006). Inhibitors of quorum sensing (QS) process are also called quorum quenchers (QQs) or quorum sensing inhibitors (QSI). Quorum sensing inhibitors (QSI) are non-bacteriostatic organisms/molecules that can control the virulence of pathogens through interference with quorum sensing, enabling the host to use its own protection mechanisms to control the pathogen (Hentzer, Eberl et al. 2003; Rasmussen and Givskov 2006; Dong, Wang et al. 2007; Wang, Morohoshi et al. 2008; Galloway, Hodgkinson et al.