S R Krupesha Sharma

Epitope analysis of white spot syndrome virus of Penaeus monodon by in vivo neutralization assay employing a panel of monoclonal antibodies

A panel of six monoclonal antibodies (MAbs) against the major envelope proteins VP18, VP26 and VP28 of white spot syndrome virus (WSSV) was evaluated for neutralization of the virus in vivo in Penaeus monodon. WSSV stock diluted to 1 x 10⁻⁶ resulting in 100% mortality on 12 day post injection (dpi) was used as optimum infectious dose of virus for challenge. Constant quantity (100 μg/ml) of MAbs C-5, C-14, C-33, C-38, C-56 and C-72 was incubated separately with WSSV (1 x 10⁻⁶ dilution) at 27 °C for 90 min and injected to shrimp. WSSV infection was neutralized by the MAbs C-5, C-14 and C-33 with a relative percent survival (RPS) of 60, 80 and 60 on 12 dpi, respectively compared to 100% mortality in positive control injected with WSSV alone. MAbs C-38, C-56 and C-72 could neutralize WSSV infection with RPS on 12 dpi of 40, 30 and 30, respectively. Shrimp injected with WSSV (1 x 10⁻⁶ dilution) incubated with panel of the MAbs at 100 μg/ml separately were subjected to nested PCR analysis at 0, 8, 12, 24, 36, 48 and 72 hour post injection (hpi) to provide further evidence for neutralization. MAbs C-5, C-14 and C-33 showed delay in WSSV positivity by 24 and 48 hpi by 2nd and 1st step PCR, respectively. MAbs C-38, C-56 and C-72 showed WSSV positivity by 12 and 24 hpi by 2nd and 1st step PCR, respectively. Shrimp injected with WSSV alone showed WSSV positivity by 8 and 12 hpi by 2nd and 1st step PCR, respectively. The study clearly shows that infectivity of WSSV could be delayed by MAbs C-14, C-5 and C-33.

First report of isolation and characterization of Photobacterium damselae subsp. damselae from cage-farmed cobia (Rachycentron canadum).

Cobia (Rachycentron canadum) has been considered as a potential species for aquaculture because of its fast growth and commercial value. As a consequence of successful spawning and seed production, there has been a significant demand for cage farming of cobia in India (Philipose et al. 2013). Not many reports are available on diseases of cage-farmed cobia. Globally, mortality due to pasteurellosis in cage-cultured cobia caused by Photobacterium damselae subsp. piscicida has been reported (Liu, Lin & Lee 2003). Vibriosis caused by Vibrio alginolyticus, V. harveyi, V. parahemolyticus and V. vulnificus has also been responsible for mortalities in cage-cultured cobia (Rajan et al. 2001; Liu et al. 2004). Photobacterium damselae subsp. damselae was originally isolated from the skin lesions of damsel fish, Chromis punctipinnis (Love et al. 1981). Subsequently, diseases caused by this pathogen have been reported in several cultivable fish species like seabream (Vera, Navas & Fouz 1991), eel (Ketterer & Eaves 1992), turbot (Fouz et al. 1992), ovate pompano (Zhao et al. 2009) and Asian seabass (Kanchanopas-Barnette et al. 2009). Infection caused by P. damselae subsp. damselae has also been recorded in marine mammals like dolphins (Fujioka et al. 1988) and several wild fish species (Han et al. 2009). Pathogenicity of this bacterium in several marine fish species and humans has been reviewed (Rivas, Lemos & Osorio 2013a). There have been no reports on mortality caused by this pathogen in cobia. This study was envisaged with the objectives to describe the disease epizootic caused by P. damselae subsp. damselae in cage-farmed cobia and characterize the pathogen.

Histopathological findings on innate responses of white spot disease positive Penaeus monodon (Fabricius) under semi-intensive culture

1 Fish Pathology and Biotechnology Laboratory, Department of Aquaculture, College of Fisheries, Karnataka Veterinary, Animal and Fishery Science University, Mangalore, India 2 Central Inland Fisheries Research Institute, Barrackpore, Kolkata, West Bengal, India 3 University of Pittsburgh School of Medicine, Pittsburgh, PA, USA 4 Network of Aquaculture Centres in Asia Pacific (NACA), Kasetsart University Campus, Bangkok, Thailand 5 Central Marine Fisheries Research Institute KARWAR, Karnataka, India 6 Aquaculture Program and Spices Production, IDH, The Sustainable Trade Initiative, Hanoi, Vietnam