Biology subjects

Thaiue, D.

Publications and source records attributed to Thaiue, D..

3 recordsLinked to original sources

bioRxiv2022

Wenzhou shrimp virus 8 (WZV8) diagnosis by unique inclusions in shrimp hepatopancreatic E-cells and by RT-PCR

The genome sequence of Wenzhou shrimp virus 8 (WzSV8) (GenBank record KX883984.1) was described in 2015 from wide screening for RNA viruses in aquatic animals. A closely related sequence (GenBank record OK662577.1) from the whiteleg shrimp Penaeus vannamei was deposited in 2021 under the name Penaeus vannamei picornavirus (PvPV). In 2022 another closely related sequence (GenBank accession: OP265432) was submitted under the name Penaeus vannamei solinvivirus (PvSV). In 2021, prior to the publication of PvPV and PvSV, we used an RT-PCR method devised from the sequence of KX883984.1 (described herein) to screen for WzSV8 in specimens of cultivated shrimp. Samples that gave positive RT-PCR results were subsequently tested by in situ hybridization (ISH) analysis to identify virus target tissues. Several tissues gave positive ISH results within morphologically normal nuclei. Thus, these tissues were of no use for diagnosis of WzSV8 by normal histological analysis. However, unique basophilic, cytoplasmic inclusions within vacuoles in the hepatopancreatic E-cells were also found in the same WzSV8-positive shrimp specimens, sometimes accompanied by a smaller eosinophilic inclusion. We call these Lightner double Inclusions (LDI) that can be considered pathognomonic for diagnosis of WzSV8 infection when detected using the light microscope. Although no current proof of WzSV8 is the cause of disease, it is important to investigate new viruses and related tissue anomalies, even from normal cultivated shrimp, to determine whether they may have any relationship to significant negative effects on the production of cultivated shrimp.

zoology↗

bioRxiv2020

Infectious myonecrosis virus (IMNV) and decapod iridescent virus 1 (DIV1) detected in Penaeus monodonfrom the Indian Ocean

Infectious myonecrosis virus (IMNV) was first discovered in the Americas in 2004 as a new lethal pathogen of cultivated whiteleg shrimp Penaeus vannamei, but infections were not lethal for the giant tiger shrimp Penaeus monodon. In 2007, it was reported in diseased P. vannamei cultivated in Indonesia but, until recently, not from other countries in Asia. Decapod iridescent virus (DIV1) was first reported from China in 2016 and is lethal for the crayfish Cherax quadricarinatus and Procambarus clarkii, for the penaeid shrimp P. vannamei and P. chinensis and for the palaemonid shrimp Macrobrachium rosenbergii and Exopalaemon carinicauda. It has not yet been reported from other Asian countries. Here we describe the occurrence of positive test results for IMNV and DIV1 using polymerase chain reaction (PCR) technology during screening of grossly normal, broodstock-size, wild P. monodon captured from the Indian Ocean and held in a biosecurity facility for screening. Amplicons for each virus were obtained from two widely separated targets in the relevant viral genomes listed at GenBank, and sequencing revealed 99-100% identity to the targets for each virus. Based on these results, the captured specimens were destroyed. The results raised the possibility that grossly normal, captured P. monodon might serve as potential vehicles for introduction of IMNV and/or DIV1 to shrimp hatcheries and farms. Thus, we recommend that appropriate precautions be taken to avoid this possibility.

zoology↗

bioRxiv2020

Potential universal PCR method to detect decapod hepanhamaparvovirus (DHPV) in crustaceans

Parvoviruses that infect the hepatopancreas (HP) of the penaeid shrimp Penaeus chinensis, P. monodon, and P. merquiensis were previously called hepatopancreatic parvoviruses (HPV). They are now classified in the family Parvoviridae, sub-family Hamaparvovirinae as members of the same genus called Hepanhamaparvovirus and referred to as decapod hepanhamaparvovirus, designated here as DHPV. However, a virus that causes similar lesions in the HP of the giant river prawn Macrobrachium rosenbergii resembles hepanhamaparvoviruses by microscopy and histochemistry. Unfortunately, no genome information is yet available and PCR detection methods that work for DHPV in P. monodon do not work with M. rosenbergii. For hatchery samples of M. rosenbergii in Thailand with DHPV-like lesions, we hypothesized it might be possible to design primer pairs from 8 full DHPV genome sequences at GenBank for use in PCR detection of DHPV in M. rosenbergii. Using this strategy, we successfully designed a new set of primers and a PCR protocol called the DHPV-U method that gave an amplicon with DNA extracts from larvae of M. rosenberigii samples that showed DHPV-like lesions, while extracts from normal larvae gave none. DNA extracts from P. monodon infected with DHPV also gave amplicons. At the same time, the normal PCR method for DHPV in P. monodon gave no amplicon with the M. rosenbergii DNA extracts. The DHPV-U amplicons from P. monodon and M. rosenbergii shared 99% sequence identity, and in situ hybridization (ISH) assays using the DIG-labeled amplicon gave positive histochemical results in the HP tissue of both P. monodon and M. rosenbergii. The DHPV-U method is now being used in Thailand for detection of DHPV in both P. monodon and M. rosenbergii. Overall, the results support the proposal that the HP virus in M. rosenbergii is also a hepanhamaparvovirus. Based on 100% sequence identity of the target region in the currently published DHPV sequences at GenBank, the DHPV-U method may also work for detection of other DHPV isolates.

molecular biology↗