Vertical Transmission of White Spot Syndrome Virus (WSSV) under Different Salinities in Experimental Conditions
Perumalla Papaiah
Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Pathology Division, Annamalai University, Parangipettai - 608 502, Tamil Nadu, India.
Arundathy Anandanatesan
Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Pathology Division, Annamalai University, Parangipettai - 608 502, Tamil Nadu, India.
Yuvaraj Prabhu
Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Pathology Division, Annamalai University, Parangipettai - 608 502, Tamil Nadu, India.
IyyapanTamil Selvan
Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Pathology Division, Annamalai University, Parangipettai - 608 502, Tamil Nadu, India.
Vijayanand Packiaraj *
Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Pathology Division, Annamalai University, Parangipettai - 608 502, Tamil Nadu, India.
Abdul Malik Jainulapudheen
Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Pathology Division, Annamalai University, Parangipettai - 608 502, Tamil Nadu, India.
Ayyaru Gopalakrishnan
Centre of Advanced Study in Marine Biology, Faculty of Marine Sciences, Pathology Division, Annamalai University, Parangipettai - 608 502, Tamil Nadu, India.
Inayathullah Neyasudeen
Sophisticated Biosciences Laboratory Chennai, Tamil Nadu, India.
*Author to whom correspondence should be addressed.
Abstract
White Spot Syndrome Virus (WSSV) remains one of the most destructive pathogens in shrimp aquaculture, yet the influence of environmental salinity on its transmission dynamics and disease progression is not fully understood. This study aimed to evaluate the effect of salinity on the vertical transmission and mortality patterns of WSSV in Litopenaeus vannamei through cohabitation with naturally infected Scylla olivacea. A total of 420 WSSV-free shrimp and 35 naturally WSSV-positive crabs were used in a controlled cohabitation experiment across seven salinity treatments (0, 5, 15, 20, 25, 30, and 35 ppt). For each salinity, six tanks were maintained: one control tank containing only shrimp and five replicate exposure tanks, each stocked with 10 shrimp and one infected crab, resulting in 42 experimental tanks. Shrimp were monitored for 24 days for clinical signs, mortality, and WSSV infection, which was confirmed using gross pathology and PCR analysis. Kaplan–Meier survival analysis revealed a strong salinity-dependent response, with rapid and early mortality occurring at low salinities (0–5 ppt), while salinities ≥20 ppt significantly delayed disease onset and reduced mortality rates. Intermediate survival patterns were observed at 15 ppt. Statistical comparisons confirmed significantly lower survival at low salinities compared with higher salinity treatments. Overall, the study demonstrates that although WSSV transmission occurs across all salinity conditions, higher salinities markedly suppress disease progression and delay mortality. These findings highlight salinity as a critical environmental regulator of WSSV pathogenesis and provide practical insights for disease management strategies in shrimp aquaculture, particularly in estuarine and seasonally fluctuating salinity regimes.
Keywords: White Spot Syndrome Virus (WSSV), salinity, vertical transmission, Litopenaeus vannamei, Scylla olivacea