Disinfection of Perinereis aibuhitensis eggs with peroxymonosulfate to eliminate covert mortality nodavirus (CMNV)

Abstract

Perinereis aibuhitensis is an essential bait for prompting ovarian development and sexual maturation in aquaculture shrimp broodstock. It is common for shrimp to become infected with pathogens by ingesting feed containing potential viruses. To prevent P. aibuhitensis being live feeds for shrimp broodstock from transmitting pathogens, we evaluated the disinfection effect of peroxymonosulfate (PMS) against covert mortality nodavirus (CMNV) by carrying out Oryzias melastigma (marine medaka) challenge assay and testing CMNV-exposed P. aibuhitensis eggs. In the marine medaka injected with PMS (15 and 20 ppm (ppm))-inactivated CMNV, no CMNV was detected at 6 and 12 days post-infection (d.p.i.) by using quantitative reverse transcription PCR (RT-qPCR). As well, no CMNV probe positive signal and pathological signs caused by CMNV in these marine medaka were present in situ hybridization (ISH) and histopathology assays. CMNV was not detected in the nectochaeta larvae originated from CMNV-exposed P. aibuhitensis eggs treated with PMS (5, 10, 15 and 20 ppm) for 1 min. In addition, nereids treated with 15 ppm PMS for 1 min had higher hatchability. Even at low concentrations of PMS-treated eggs, the hatchability was higher than that of the no-PMS-treated group, and no adverse effects on larval development after hatching were observed. Our study showed that disinfection of CMNV-exposed eggs by PMS is feasible. Disinfection of P. aibuhitensis eggs with PMS could reduce the risk of transmission of CMNV. Within acceptable limits for hatchery spawn losses, the recommended disinfection dose of PMS is 15 ppm for 1 min. This study laid the foundation for the culture of specific pathogen-free P. aibuhitensis and to provide biological baits with no pathogenic risk to farmed shrimp.