Subsequently, Tan et al. also published work on competitive PCR assay quantification of WSSV in tissues, using P. monodon as the study species [10]. Li et al. reported that infection

of the crayfish Procambarus clarkii with 103–105 WSSV copies resulted in a mortality of 100% after 10 days, whereas administration of 1.06 × 106 virus copies resulted in 100% mortality after 3–7 days [3]. Recently, viral loads measured in shrimp were 109–1010 copy Paclitaxel molecular weight numbers/g of tissue at the onset of mortality [11]. White spot syndrome virus outbreaks coincide with the onset of the monsoon in Malaysia, when intense rainfall decreases the salinity of aquaculture ponds [12]. It has been suggested that acute salinity find more changes over a particular range weaken the immune systems of shrimp, making them highly vulnerable to pathogens. In shrimp culture, few studies have been performed on environmental influences over disease susceptibility and the influence of salinity on immune variables that affect disease outbreaks [13]. Fenneropenaeus indicus is one of the major commercial species. Changes in environmental factors such as salinity may regulate (both positively

and negatively) this species’ immune and biochemical variables, which could lead to greater susceptibility to, and increased mortality from, WSSV. Accordingly, we carried out the present study to investigate the role of salinity on the susceptibility of F. indicus to WSSV and the influence of WSSV on relevant metabolic and immune variables. We here report inducing acute variations in rearing salinity and their impact on biochemical and immune variables of hemolymph of F. indicus challenged with WSSV. White spot syndrome virus-free F. indicus (confirmed by WSSV PCR assay) produced Rutecarpine from specific pathogen-free brooders were collected from a shrimp farm at Tuticorin, Tamil Nadu, India and acclimatized

in the laboratory for 2 weeks before experimentation. The animals were kept in tanks with sand beds supplied with a flow-through system of sand-filtered, ozone-treated sea water at 28 ± 0.5°C. The animals were fed with commercial crumbled feed at 5% of body weight per day before and during the experiment. F. indicus in the intermolt stage were used for the study. The molt stage was identified by finding partial retraction of the epidermis on examination of the uropods [15]. The shrimp ranged from 14.7 to 20.3 g (mean ± standard deviation, 17.75 ± 3.60 g) with no significant size differences among the treatments. Before starting the experiment, the disease-free status of randomly selected samples of the experimental shrimp was screened by PCR for WSSV infection. WSSV-free F. indicus maintained at 25 g/L were selected for further studies. White spot syndrome virus inoculums were prepared from WSSV-infected shrimp (Fenneropenaeus indicus) with prominent white spots collected from shrimp farms in Tuticorin, Tamil Nadu, India.