Conjugative Transfer of Acute Hepatopancreatic Necrosis Disease-Causing pVA1-Type Plasmid Is Mediated by a Novel Self-Encoded Type IV Secretion System.

The pathogenic pVA1-type plasmids that carry toxin genes are the genetic basis for to cause acute hepatopancreatic necrosis disease (AHPND), a lethal shrimp disease posing an urgent threat to shrimp aquaculture. Emerging evidence also demonstrate the rapid spread of pVA1-type plasmids across species. The pVA1-type plasmids have been predicted to encode a self-encoded type IV secretion system (T4SS).

Complete Genome Sequence of Macrobrachium rosenbergii Golda Virus (MrGV) from China.

In a meta-transcriptome study of the giant freshwater prawn sampled in 2018 from a hatchery, we identified a variant of Macrobrachium rosenbergii golda virus (MrGV) in postlarvae without clinical signs. The virus belongs to the family , and the genome of this MrGV variant, Mr-18, consisted of 28,957 nucleotides, including 4 open reading frames (ORFs): (1) ORF1a, encoding a 3C-like protein (3CLP) (4933 aa); (2) ORF1b, encoding a replicase polyprotein (2877 aa); (3) ORF2, encoding a hypothetical nucleocapsid protein (125 aa); and (4) ORF3, encoding a glycoprotein (1503 aa). ORF1a overlaps with ORF1b with 40 nucleotides, where a -1 ribosomal frameshift with slippage sequence 5'-GGGUUUU-3' produces the pp1ab polyprotein.

A Novel Bunyavirus Discovered in Oriental Shrimp ().

Herein, we describe a novel bunyavirus, oriental wenrivirus 1 (OWV1), discovered in moribund oriental shrimp () collected from a farm in China in 2016. Like most bunyaviruses, OWV1 particles were enveloped, spherical- to ovoid-shaped, and 80-115 nm in diameter. However, its genome was found to comprise four segments of (-)ssRNA.

Natural infection of covert mortality nodavirus affects Zebrafish (Danio rerio).

Covert mortality nodavirus (CMNV), a novel aquatic pathogen, causes viral covert mortality disease (VCMD) in shrimps and also known to infect farmed marine fish. To date, there has no report regarding the ability of this virus to infect freshwater fish. In this study, we screened and discovered CMNV-positive freshwater zebrafish individuals by reverse transcription-nested PCR (RT-nPCR).

A Novel Virus of Associated with Sexual Precocity in .

Since 2010, sexual precocity, a typical sign of the iron prawn syndrome (IPS), resulting in the reduced size of farmed giant freshwater prawns , has caused substantial production losses. However, the cause of IPS was not clear. We ran tests for eight major shrimp pathogens, but none were detected from IPS-affected prawns.

The Complete Genome of an Endogenous Nimavirus () From the Pacific Whiteleg Shrimp () .

White spot syndrome virus (WSSV), the lone virus of the genus under the family , is one of the most devastating viruses affecting the shrimp farming industry. Knowledge about this virus, in particular, its evolution history, has been limited, partly due to its large genome and the lack of other closely related free-living viruses for comparative studies. In this study, we reconstructed a full-length endogenous nimavirus consensus genome, (279,905 bp), in the genome sequence of () breed Kehai No.

Quantification of (EHP) in Penaeid Shrimps from Southeast Asia and Latin America Using TaqMan Probe-Based Quantitative PCR.

We developed a qPCR assay based on the -tubulin gene sequence for the shrimp microsporidian parasite (EHP). This assay reacted with the hepatopancreas (HP) of EHP-infected shrimps, and the highest copy numbers were found in HP and feces samples from Southeast Asian countries (10-10 copies mg), while HP samples from Latin America, , and EHP-contaminated water showed lower amounts (10-10 copies mg or mL of water). No false positive was found with the normal shrimp genome, live feeds, or other parasitic diseases.

Conjugative Transfer of the pVA1-Type Plasmid Carrying the Genes Results in the Formation of New AHPND-Causing .

Acute hepatopancreatic necrosis disease (AHPND) has caused sharp declines in aquaculture industries of whiteleg shrimp in Asia and the Americas since 2010. , and have been proved to cause AHPND. However, the mechanisms underlying the burgeoning number of species that cause AHPND is not known.

Infection of covert mortality nodavirus in Japanese flounder reveals host jump of the emerging alphanodavirus.

Interspecies transmission of viruses, where a pathogen crosses species barriers and jumps from its original host into a novel species, has been receiving increasing attention. Viral covert mortality disease, caused by covert mortality nodavirus (CMNV), is an emerging disease that has recently had a substantial impact on shrimp aquaculture in Southeast Asia and Latin America. While investigating the host range of CMNV, we found that this virus is also capable of infecting populations of the farmed Japanese flounder Paralichthys olivaceus, a vertebrate host.

Phage Application for the Protection from Acute Hepatopancreatic Necrosis Disease (AHPND) in .

Acute hepatopancreatic necrosis disease (AHPND) caused by has been one of the most problematic diseases in marine shrimp aquaculture throughout Southeast Asia and Latin America. To evaluate the effectiveness of a bacteriophage (phage) treatment for AHPND, a series of bioassays were carried out in a marine shrimp () model using an AHPND- strain that is highly pathogenic to shrimp. We monitored the mortality and histopathological changes during phage treatment.

Complete Genome Sequence of Acute Hepatopancreatic Necrosis Disease-Causing LA16-V1, Isolated from Cultured in a Latin American Country.

We report here the complete genome sequence of , isolated from cultured in a Latin American country. The Tn-like transposon and genes were encoded on the plasmid pLA16-2. These data support the geographical variations in the virulence plasmid found among acute hepatopancreatic necrosis disease (AHPND)-causing isolates from Latin America and Asia.

Aquaculture genomics, genetics and breeding in the United States: current status, challenges, and priorities for future research.

Advancing the production efficiency and profitability of aquaculture is dependent upon the ability to utilize a diverse array of genetic resources. The ultimate goals of aquaculture genomics, genetics and breeding research are to enhance aquaculture production efficiency, sustainability, product quality, and profitability in support of the commercial sector and for the benefit of consumers. In order to achieve these goals, it is important to understand the genomic structure and organization of aquaculture species, and their genomic and phenomic variations, as well as the genetic basis of traits and their interrelationships.

Dense populations of the microsporidian Enterocytozoon hepatopenaei (EHP) in feces of Penaeus vannamei exhibiting white feces syndrome and pathways of their transmission to healthy shrimp.

White feces syndrome (WFS) is an emerging problem for penaeid shrimp farming industries in SE Asia countries, Thailand, Malaysia, Vietnam, Indonesia, China, and in India. This occurrence of this syndrome is usually first evidenced by the appearance of white fecal strings floating on surface of the shrimp ponds. The gross signs of affected shrimp include the appearance of a whitish hindgut and loose carapace, and it is associated with reduced feeding and growth retardation.

Detection of a new microsporidium Perezia sp. in shrimps Penaeus monodon and P. indicus by histopathology, in situ hybridization and PCR.

Samples of microsporidia-infected shrimps exhibiting clinical signs of cotton shrimp disease were collected from Madagascar, Mozambique, and the Kingdom of Saudi Arabia from 2005 to 2014. The tails of the infected shrimps appeared opaque and whitish; subsequent histological examination revealed the presence of cytoplasmic inclusions and mature spores in tissues of the muscle, hepatopancreas, gills, heart, and lymphoid organ. PCR analysis targeting the small subunit rDNA (SSU rDNA) from infected samples resulted in the amplification of a 1.

Genotyping of virulence plasmid from Vibrio parahaemolyticus isolates causing acute hepatopancreatic necrosis disease in shrimp.

Acute hepatopancreatic necrosis disease (AHPND) has caused severe mortalities in farmed penaeid shrimp throughout SE Asia and Mexico. The causative agent of AHPND is the marine bacterium Vibrio parahaemolyticus, which secretes PirA- and PirB-like binary toxin that caused deterioration in the hepatopancreas of infected shrimp. The genes responsible for the production of this toxin are located in a large plasmid residing within the bacterial cells.

Development of in situ hybridization and PCR assays for the detection of Enterocytozoon hepatopenaei (EHP), a microsporidian parasite infecting penaeid shrimp.

A microsporidian parasite, Enterocytozoon hepatopenaei (abbreviated as EHP), is an emerging pathogen for penaeid shrimp. EHP has been found in several shrimp farming countries in Asia including Vietnam, Thailand, Malaysia, Indonesia and China, and is reported to be associated with growth retardation in farmed shrimp. We examined the histological features from infected shrimp collected from Vietnam and Brunei, these include the presence of basophilic inclusions in the hepatopancreas tubule epithelial cells, in which EHP is found at various developmental stages, ranging from plasmodia to mature spores.

Extended genome sequences of penaeid shrimp infectious myonecrosis virus strains from Brazil and Indonesia.

New sequencing studies of the nonsegmented dsRNA genome of penaeid shrimp infectious myonecrosis virus (IMNV), a tentatively assigned member of the family Totiviridae, identified previously unread sequences at both genome termini in three previously analyzed IMNV strains, one from Brazil (the prototype strain of IMNV) and two from Indonesia. The new sequence determinations add >600 nt to the 5' end of the genomic plus strand of each strain, increasing the length of the 5' nontranslated region to at least 469-472 nt and the length of the upstream open reading frame (ORF1) translation product by at least 48 aa. These new findings are similar to recent ones for two other IMNV strains (GenBank KF836757.

Photorhabdus insect-related (Pir) toxin-like genes in a plasmid of Vibrio parahaemolyticus, the causative agent of acute hepatopancreatic necrosis disease (AHPND) of shrimp.

The 69 kb plasmid pVPA3-1 was identified in Vibrio parahaemolyticus strain 13‑028/A3 that can cause acute hepatopancreatic necrosis disease (AHPND). This disease is responsible for mass mortalities in farmed penaeid shrimp and is referred to as early mortality syndrome (EMS). The plasmid has a GC content of 45.

Homologues of insecticidal toxin complex genes within a genomic island in the marine bacterium Vibrio parahaemolyticus.

Three insecticidal toxin complex (tc)-like genes were identified in Vibrio parahaemolyticus 13-028/A3, which can cause acute hepatopancreatic necrosis disease in penaeid shrimp. The three genes are a tcdA-like gene (7710 bp), predicted to code for a 284-kDa protein; a tcdB-like gene (4272 bp), predicted to code for a 158-kDa protein; and a tccC3-like gene (2916 bp), predicted to encode a 107-kDa protein. All three predicted proteins contain conserved domains that are characteristic of their respective Tc proteins.

Novel, closely related, white spot syndrome virus (WSSV) genotypes from Madagascar, Mozambique and the Kingdom of Saudi Arabia.

White spot syndrome virus (WSSV) is highly pathogenic to penaeid shrimp and has caused significant economic losses in the aquaculture industry around the world. During 2010 to 2012, WSSV caused severe mortalities in cultured penaeid shrimp in Saudi Arabia, Mozambique and Madagascar. To investigate the origins of these WSSV, we performed genotyping analyses at 5 loci: the 3 open reading frames (ORFs) 125, 94 and 75, each containing a variable number of tandem repeats (VNTR), and deletions in the 2 variable regions, VR14/15 and VR23/24.

A histological variant of white spot syndrome virus (WSSV) from the Kingdom of Saudi Arabia.

White spot syndrome virus (WSSV) is highly pathogenic to penaeid shrimp. The major targets of WSSV infection are tissues of ectodermal and mesodermal embryonic origin, predominantly the cuticular epithelium and subcuticular connective tissues. Recently, we discovered a WSSV variant in Penaeus indicus that heavily infects the subcuticular connective tissue, with very slight indications in the cuticular epithelium.

New genotypes of white spot syndrome virus (WSSV) and Taura syndrome virus (TSV) from the Kingdom of Saudi Arabia.

White spot syndrome virus (WSSV) and Taura syndrome virus (TSV) are highly pathogenic to penaeid shrimp and have caused significant economic losses in the shrimp culture industry around the world. During 2010 and 2011, both WSSV and TSV were found in Saudi Arabia, where they caused severe mortalities in cultured Indian white shrimp Penaeus indicus. Most outbreaks of shrimp viruses in production facilities can be traced to the importation of infected stocks or commodity shrimp.

Protection from yellow head virus (YHV) infection in Penaeus vannamei pre-infected with Taura syndrome virus (TSV).

Pacific white shrimp Penaeus vannamei that were pre-exposed to Taura syndrome virus (TSV) and then challenged with yellow head virus (YHV) acquired partial protection from yellow head disease (YHD). Experimental infections were carried out using specific-pathogen-free (SPF) shrimp which were first exposed per os to TSV; at 27, 37 and 47 d post infection they were then challenged by injection with 1 × 104 copies of YHV per shrimp (designated the TSV-YHV group). Shrimp not infected with TSV were injected with YHV as a positive control.

Histopathological characterization and in situ detection of Callinectes sapidus reovirus.

A reovirus (tentatively designated as Callinectes sapidus reovirus, CsRV) was found in the blue crabs C. sapidus collected in Chesapeake Bay in 2005. Histological examination of hepatopancreas and gill from infected crabs revealed eosinophilic to basophilic, cytoplasmic, inclusions in hemocytes and in cells of connective tissue.