Experimental transmission and tissue tropism of Macrobrachium rosenbergii nodavirus (MrNV) and its associated extra small virus (XSV)

Department of Zoology, C. Abdul Hakeem College, Melvisharam 632 509, Vellore District, Tamil Nadu, India.
Diseases of Aquatic Organisms (Impact Factor: 1.59). 01/2005; 62(3):191-6. DOI: 10.3354/dao062191
Source: PubMed

ABSTRACT White tail disease (WTD) was found to be a serious problem in hatcheries and nursery ponds of Macrobrachium rosenbergii in India. The causative organisms have been identified as M. rosenbergii nodavirus (MrNV) and its associated extra small virus (XSV). Experimentally transmitted to healthy animals, they caused 100% mortality in post-larvae but failed to cause mortality in adult prawns. The RT-PCR assay revealed the presence of both viruses in moribund post-larvae and in gill tissue, head muscle, stomach, intestine, heart, hemolymph, pleopods, ovaries and tail muscle, but not in eyestalks or the hepatopancreas of experimentally infected adult prawns. The presence of these viruses in ovarian tissue indicates the possibility of vertical transmission. Pleopods have been found to be a suitable organ for detecting these viruses in brooders using the RT-PCR technique.

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Available from: A S Sahul Hameed, Feb 20, 2015
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    • "MrNV has been placed in the family of Nodaviridae based on characteristics and genome sequences of the virus (Sahul Hameed et al. 2004; Sri Widada & Bonami 2004). MrNV is a small, icosahedral, non-enveloped virus, 26–27 nm in diameter, exhibiting a density of 1.27–1.28 "
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    ABSTRACT: Macrobrachium rosenbergii nodavirus (MrNV) that causes white tail disease (WTD) is an emerging disease that contributes to serious production losses in Macrobrachium hatcheries worldwide. Mosquito cell lines (C6/36) have been reported to support the growth of MrNV and used to observe the cytopathic effects (CPE) in infected cells. This study determined the susceptibility of C6/36 mosquito cells to the Australian isolate of MrNV in order to use fewer animals in further investigations. Different staining methods were used to observe MrNV viral activity in C6/36 cells. Typical cytopathic effects such as vacuolation and viral inclusion bodies were observed in infected C6/36 cells with H&E and Giemsa staining. With acridine orange, it was easier to detect presumptive MrNV messenger ribonucleic acid in the infected cells. Using neutral red staining to measure mitochondrial activity showed light absorption of infected cells maximized at day 4 (O.D. = 0.6) but was significantly lower (chi-square = 41.265, df = 1, P < 0.05) than control groups (O.D. = 2) which maximized at day 12. Using trypan blue staining to count the number of cells with disrupted cell membranes, the maximum number of presumptively dead cells at day 8 (4 × 10(5) cells) in infected treatments was higher than the control treatment at day 10 (1.8 × 10(5) cells). However, TaqMan real-time PCR did not confirm the replication of MrNV in the cells over 14 days. The mean viral copies and mean cycle times of positive samples were stable at 2.07 × 10(4) and 24.12, respectively. Limited evidence of viral replication was observed during four serial passages. This study determined the mortality of the C6/36 cell line to the Australian isolate of MrNV but suggests limited patent replication was occurring. Trying different cell lines or adapting the virus to the C6/36 cells may be necessary to successfully replicate Australian MrNV in cell lines.
    Journal of Fish Diseases 11/2012; 36(4). DOI:10.1111/j.1365-2761.2012.01414.x · 1.51 Impact Factor
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    • "MrNV has been placed in the family of Nodaviridae (Alphanodavirus) based on its characteristics and genome sequences (Bonami and Sri Widada, 2011; Sahul Hameed et al., 2004). MrNV is a small icosahedral non-enveloped virus, 26 to 27 nm in diameter. "
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    ABSTRACT: White tail disease (WTD) caused by Macrobrachium rosenbergii nodavirus (MrNV) has been found in the giant freshwater prawn (Macrobrachium rosenbergii) and has recently been the cause of high mortalities in many countries such as India, China, Taiwan and Thailand. In mid 2004, the index case of WTD in Australia presented in adult broodstock M. rosenbergii from Flinders River in western Queensland. In order to understand the phylogenetic relationship of the Australian recognizate of MrNV to other MrNV recognizates, the complete sequences of the Australian MrNV (RNA1 and RNA2) were determined. Nucleotide and phylogenetic analysis revealed that the Australian strain of MrNV (RNA1) was between 94% and 97% identical to Malaysian, the French West Indies, Chinese and the Thai recognizates. Also, the nucleotide sequence of the Australian MrNV (RNA2) was 92% identical to the French West Indies, Chinese and the Thai recognizates. The nucleotide comparison of protein B2 showed a different relationship between MrNV and fish nodaviruses. However, the phylogenetic tree of protein B2 determined that some fish nodaviruses are closely related to insect nodavirus. These results can be used to develop effective diagnostic tests and design specific RNA interference (RNAi) against protein B2 to control other nodaviruses in the future.
    Aquaculture 11/2012; 366/367:98-104. DOI:10.1016/j.aquaculture.2012.08.049 · 1.83 Impact Factor
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    ABSTRACT: Post-larvae of Macrobrachium rosenbergii infected with white tail disease were collected from hatcheries and nursery ponds in India. The causative organisms have been identified as Macrobrachium rosenbergii nodavirus (MrNV) and extra small virus (XSV). A one-step multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) has been developed to detect these viruses simultaneously in naturally and experimentally infected prawns. Several parameters were assayed in order to optimize the protocol for simultaneous detection. Naturally and experimentally infected prawns showed two prominent bands of 681 and 500 bp for MrNV and XSV, respectively, as in separate RT-PCR assays. Experimentally infected adult prawns showed two bands for these two viruses in all the organs, except hepatopancreas and eyestalk, as seen in normal RT-PCR. The sensitivity test carried out on the primer sets of MrNV and XSV revealed that these primers could simultaneously detect the two viruses at a level of 25 fg of total RNA prepared from infected samples using this multiplex RT-PCR protocol.
    Journal of Fish Diseases 03/2005; 28(2):65-9. DOI:10.1111/j.1365-2761.2004.00606.x · 1.51 Impact Factor
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