Parvo-like virus in the hepatopancreas of freshwater prawns Macrobrachium rosenbergii cultivated in Thailand

Abstract

A survey of cultivated giant freshwater prawns Macrobrachium rosenbergii from Thailand revealed the presence of unusual spherical to ovoid inclusions in nuclei of hepatopancreas tubule epithelial cells. These began as small eosinophilic inclusions that became more basophilic as they increased in size. They were present in both R-cells and E-cells but were largest and deeply basophilic only in the E-cells. Confocal laser microscopy revealed that stained nucleic acid fluorescence from the inclusions was lost by treatment with DNase I specific for double-and single-stranded DNA and also lost or reduced by treatment with mungbean nuclease specific for single-stranded nucleic acids. Transmission electron microscopy (TEM) revealed that the inclusions contained tightly packed, unenveloped, viral-like particles of approximately 25 to 30 nm diameter, resembling those produced by shrimp parvoviruses. However, PCR, in situ hybridization and immunohistochemical tests for shrimp parvoviruses previously reported from Thailand were all negative. These results suggested that the inclusions contained a parvo-like virus, not previously reported from M. rosenbergii in Thailand. KEY WORDS: Macrobrachium rosenbergii · Hepatopancreas · Parvo-like virus · Histopathology · Electron microscopy Resale or republication not permitted without written consent of the publisherDis Aquat Org 85: [167][168][169][170][171][172][173] 2009 natural infections of M. rosenbergii is similar to the one known as hepatopancreatic parvovirus (HPV) in penaeid shrimp (Anderson et al. 1990, Lightner et al. 1994) based on histopathology (Bonami et al. 1995, Lightner 1996. A recent proposal to the International Committee on Taxonomy of Viruses (Tijssen 2008) recommends that these penaeid shrimp parvoviruses be included in a new genus, Hepanvirus, in the sub-family Densovirinae of the family Parvoviridae as Penaeus monodon densovirus (PmDNV), Penaeus merguiensis densovirus (PmergDNV) and Penaeus chinensis densovirus (PchinDNV). These differ in genome size and organization and target tissue from another penaeid shrimp parvovirus also included in the sub-family Densovirinae, but in the genus Brevidensovirus, as Penaeus stylirostris densovirus (PstDNV) (Tattersall et al. 2005). PstDNV was formerly called infectious hypodermal and hematopoeitic necrosis virus (IHHNV) (Lightner 1996). The newly recommended names (Tattersall et al. 2005, Tijssen 2008) will be used in this manuscript, as will the ICTV method of naming shrimp viruses with non-italicized host species names and abbreviations (Fauquet et al. 2005).For successful specific pathogen free (SPF) stock development, diagnostic methods would be required for all of the pathogens included in any specific list of pathogens for M. rosenbergii. For this species, highly sensitive RT-PCR methods are available for MrNV and XSV (Romestand & Bonami 2003, Sri Widada et al. 2003, Yoganandhan et al. 2005, Pillai et al. 2006. However, for other viral pathogens, such as the parvo-like virus described above, no molec...

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

“…From 2016-2018, a project to develop specific pathogen free (SPF) M. rosenbergii contacted our research unit to diagnose the cause of unexpected mortality in larvae from a screening program to select a founder stock. The affected larvae showed typical DHPV-like lesions, as had previously been reported (Anderson, et al, 1990;Gangnonngiw, et al, 2009). At the same time, several full sequences of DHPV had accumulated at GenBank, and we hypothesized that, if the virus in M.…”

A Novel RNA Virus, Macrobrachium rosenbergii Golda Virus (MrGV), Linked to Mass Mortalities of the Larval Giant Freshwater Prawn in Bangladesh

“…Other viruses causing mortalities include Macrobrachium rosenbergii Taihu Virus (MrTV), a novel dicistrovirus associated with larval mortalities in China [ 15 ], Infectious Hypodermal and Haematopoietic Necrosis Virus (IHHNV) [ 16 ], and Decapod Iridescent Virus (DIV1) [ 17 ]. Other pathogens have been identified to infect M. rosenbergii without large mortalities including: Macrobrachium Parvo-like Virus (MPV) [ 18 ] and White Spot Syndrome Virus (WSSV) [ 19 , 20 ]. With the lack of immortal shrimp cell lines, disease challenges can be used to identify pathogenic agents infecting M. rosenbergii .…”

A novel RNA virus,Macrobrachium rosenbergiiGolda virus (MrGV), linked to mass mortalities of the larval giant freshwater prawn in Bangladesh

“…Other viruses causing mortalities include Macrobrachium rosenbergii Taihu Virus (MrTV), a novel dicistrovirus associated with larval mortalities in China (Pan et al, 2016), Infectious Hypodermal and Haematopoietic Necrosis Virus (IHHNV) (Hsieh et al, 2006), and Decapod Iridescent Virus (DIV1) (Qiu et al, 2019). Other pathogens have been identified to infect M. rosenbergii without large mortalities including: Macrobrachium Parvo-like Virus (MPV) (Gangnonngiw et al, 2009) and White Spot Syndrome Virus (WSSV) (Sahul Hameed, Charles and Anilkumar, 2000;Sarathi et al, 2008).…”