Short communication Studies on the inactivation of white spot syndrome virus of shrimp by physical and chemical treatments, and seaweed extracts tested in marine and freshwater animal models G Balasubramanian, R Sudhakaran, S Syed Musthaq, M Sarathi and A S Sahul Hameed Aquaculture Biotechnology Division, Department of Zoology, C. Abdul Hakeem College, Melvisharam, Tamil Nadu, India Keywords: disinfectants, inactivation, pH, tempera- ture, UV, white spot syndrome virus. White spot syndrome of penaeid shrimp, charac- terized by the appearance of white spots in the exoskeleton with high mortality, was first reported in early 1994 in Thailand as an accidental infection in laboratory reared shrimp (Takahashi, Itami, Maeda, Fujii, Tomonaga, Supamattaya & Boonyar- atpalin 1994; Wongteerasupaya, Vickers, Sriuraira- tana, Nash, Akarajamorn, Boonsaeng, Panyim, Tassanakajon, Withyachumnaarnkul & Flegel 1995). The causative organism of white spot syndrome is an enveloped, non-occluded and rod- shaped baculovirus, white spot syndrome virus (WSSV). This virus is responsible for severe losses to global shrimp aquaculture (Lightner 1996) and the losses in India alone have been estimated at several million dollars per year (Anonymous 1996). WSSV has been isolated and characterized from Indian shrimp, Penaeus indicus (Sahul Hameed, Anil Kumar, Stephen Raj & Kunthala 1998). Treating viral infection with common che- motherapeutants is ineffective and the development and use of virus-resistant species is time-consuming. Therefore, prevention is a logical strategy for controlling the virus, including the use of physical or chemical disinfectants in commercial shrimp farming. The inactivation of various aquatic viruses, including shrimp viruses, by physical and chemical agents have been reported by various authors (Elliott & Amend 1978; Momoyama 1989; Le Blanc & Overstreet 1991; Chen, Chang & Kou 1992; Arimoto, Sato, Maruyama, Mimura & Furusawa 1996; Chang, Chen & Wang 1998; Maeda, Itami, Furumoto, Hennie, Imamura, Kondo, Hirono, Aoki & Takahashi 1998) who determined the effects of heat, ultraviolet light, pH, desiccation and chemical disinfectants on the inactivation of baculoviral mid-gut gland necrosis virus (BMNV) and WSSV. Marine plants are used in folk and in ayurvedic (herbal) medicines. Some Indian marine plants showed antiviral activity against Newcastle disease virus, anti-vaccinia virus, Semliki forest virus, human immunodeficiency virus, hepatitis B virus, encephalomyocarditis virus (Premanathan, Chan- dra, Bajpai & Kathiresan 1992; Premanathan, Kathiresan, Chandra & Bajpai 1993; Premanathan, Kathiresan & Chandra 1994a,b, 1995; Premana- than, Nakashima, Kathiresan, Rajendran & Yama- moto 1996) and Herpes simplex virus I (Siamopoulou, Bimplakis, Iliopoulou, Vagias, Cos, Van den Berghe & Roussis 2004). In the present study, the efficacy of various physical and chemical agents, and seaweeds with previously reported antiviral activity against other viruses, for the inactivation of WSSV was investigated. The efficacy was assessed by an infectivity assay in marine and freshwater animal models, as the virus maintains infectivity in fresh water, and the Journal of Fish Diseases 2006, 29, 569–572 Correspondence A S Sahul Hameed, Aquaculture Biotechno- logy Division, Department of Zoology, C.Abdul Hakeem College, Melvisharam 632 509, Vellore Dist., Tamil Nadu, India (e-mail: cah_sahul@hotmail.com) 569 Ó 2006 Blackwell Publishing Ltd