Radical thermal therapy against infection with decapod iridescent virus 1 (DIV1)

Abstract

Decapod iridescent virus 1 (DIV1) is a newly found double-stranded DNA virus that can cause huge losses to the aquaculture industry. The potential of thermal therapy to treat and cure the disease, namely infection with DIV1 (iDIV1), in white leg shrimp Penaeus vannamei, was evaluated in this study with the thermal treatment and temperature restoration (TT/TR) protocol. After being challenged with DIV1 strain SHIV20141215 via intramuscular injection, the shrimp in different groups received a 15-day TT from 28 °C to 38 °C, respectively, and then 15-day TR at 28 °C. All shrimp in groups with TT below 32 °C died rapidly within 5 d post-infection (dpi) with confirmatory iDIV1 by TaqMan qPCR, histopathological H&E staining and ISDL, and cytopathological TEM. The development of iDIV1 was suppressed at 34 °C but revived after TT to 28 °C. Elimination of DIV1 at 36 °C was confirmed with the same survival curve of the unchallenged control group, no replication of DIV1 DNA copies, and negative results of clinical signs, histopathology, ISDL, and TEM during the TT/TR process. The reproducibility validation of TT/TR at 36 °C verified the elimination of DIV1 from the challenged shrimp. This is the first report of radical thermal therapy from the emerging disease iDIV1 using TT at 36 °C, which provides an innovative measure to cure the fatal viral infection, especially for the larvae and broodstock of shrimp varieties with special genetic properties.