White spot syndrome virus (WSSV) prevalence in wild crustaceans in the Bohai Sea

Abstract

The impacts of mariculture on coastal ecosystems are increasingly raising attention recently. To study the prevalence of white spot syndrome virus (WSSV) in wild crustaceans, a pathogenic agent of cultured shrimps, continuous and large-scale surveys in the Bohai Sea were firstly conducted from 2016 to 2018. A total of 820 samples were collected from 59 sampling sites. The results of loop-mediated isothermal amplification (LAMP) assay showed that 11 of the 19 wild species were identified to be WSSV positive. Among them, Alpheus distinguendus had the highest WSSV-positive rate at 21.9%. The percentage of WSSV positive sampling sites was 76.7%, 55.0%, 43.7% in 2016, 2017, 2018, respectively. The percentage of WSSV positive samples was 17.4%, 12.2% and 7.8%, respectively. The multiple sequence alignment and phylogenetic tree analysis showed that the WSSV VP26 gene cloned from the wild crustaceans was consistent with those from WSSV strains previously reported in India, China, Brazil, Thailand, as well as Mexico, which was clustered tightly into one branch. The presence of WSSV virions in the epithelial cells of wild southern rough shrimp Trachypenaeus curvirostris was confirmed by TEM assay, which further verifying the occurrence of WSSV infection in wild crustaceans. The results of present study demonstrated that WSSV had colonized in the populations of offshore wild crustaceans in the Bohai Sea, and the potential negative impact of WSSV prevalence on the wild crustacean populations together with marine ecosystem deserved close attention and further investigation.