IJA Volume 61, Issue 3, 2009

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    Herbal Extract Effects on White Spot Syndrome Virus (WSSV) in Shrimp (Penaeus monodon)
    (Israeli Journal of Aquaculture - BAMIGDEH, 2009) Loan, Ly T.T. ; Uyen, Nguyen H.P. ; Phuong, Vo H. ; Cuong, Doan V. ; Anh, Pham V.N. ; Hanh, Nguyen N. ; Anh, Le T.T.
    Synthetic drugs and chemicals used in aquaculture cause disadvantageous side effects, while medicines made from medicinal herbs are non-toxic, easy to use, and pollution- free. Many medicinal herbs have potent antiviral properties. The extract of Phyllanthus amarus is a lignan composed of the compounds: niranthin, phyllanthin, and hypophyllanthin which have an impact on the white spot syndrome virus (WSSV) in the shrimp, Penaeus monodon. The virucidal activities of the three substances were tested by mixing them with WSSV, followed by injection into healthy shrimp. The quantity of WSSV DNA on the gills of tested shrimp was measured before and seven days after injecting the mixture. The quantity decreased significantly after injection. Anti-virucidal activities were also assessed by observation of the mortality rates of injected shrimp. The lignan compound inactivated the virus when injected in P. monodon at a dose of 100 mg per kilogram body weight. The survival rate of the lignan injected shrimp was 96.67% , compared to the positive control in which it was only 3.33% .
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    Infectious Myonecrosis Virus (IMNV) in Pacific White Shrimp (Litopenaeus vannamei) in Indonesia
    (Israeli Journal of Aquaculture - BAMIGDEH, 2009) Taukhid ; Nur’aini, Yani Lestari
    Penaeid shrimp culture has become a leading export fishery in Indonesia. The Pacific white shrimp (Litopenaeus vannamei) was unofficially intro- duced to Indonesia in 1999, and received government approval in 2001. By the end of 2007, the Pacific white shrimp was cultured in over 17 provinces. The main constraints of shrimp culture have always been diseases, espe- cially those caused by viral agents. Taura syndrome (TS) disease was detected in Indonesia in 2002 and the disease currently affects at least ten provinces. Infectious myonecrosis (IMN) is an emerging L. vannamei dis- ease, first detected in Indonesia in May-June 2006. IMN disease causes significant mortality in growout ponds and is characterized by acute onset of gross signs: focal to extensive whitish necrotic areas in the striated mus- cle, especially of the distal abdominal segments and the tail fan. The white necrotic areas redden, similar to the color of cooked shrimp. The outbreak results in elevated mortality that was initially associated with a chronic course of persistent low level mortality. To date, IMN has been detected in East Java, Bali, and West Nusa Tenggara provinces. This paper reviews studies of IMN disease of Pacific white shrimp in Indonesia: outbreaks, sur- veillance, diagnosis, and control measures.
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    Study on the Pathogenesis of the White Spot Syndrome Virus (WSSV) on Juvenile Penaeus monodon in Vietnam
    (Israeli Journal of Aquaculture - BAMIGDEH, 2009) Doan, Cuong Van ; Pham, Anh Thi Tuyet ; Ngo, Tuyen Xuan ; Le, Phuoc Hong ; Nguyen, Hao Van
    The white spot syndrome virus (WSSV) causes disease and mortality in cul- tured and wild Penaeus monodon. In this study, specific pathogen-free P. monodon were injected with WSSV to determine in which primary organs the virus replicates and to analyze viral spread. Shrimps were injected with a low SID50 endpoint (shrimp infectious dose resulting in 50% infected shrimp) of 101.5 or a high SID50 of 104 of the virus. Six shrimps per treat- ment were collected at 0, 3, 6, 9, 12, 15, 18, 21, 24, 30, 36, 42, 48, 54, and 60 h post injection (hpi) for detection of the virus in tissues from 10 organs by immunohistochemistry. In shrimps injected with the low dose, WSSV- infected cells were first detected in the heart and antennal gland 12 hpi, then in the foregut, stomach, and gills at 18 hpi. The integument was infect- ed 24 hpi and the hematopoietic tissue, lymphoid organ, midgut, and con- nective tissues 36 hpi. In shrimps that received the high dose, the heart, antennal gland, stomach, gill, and connective and hematopoietic tissues were WSSV-positive 12-15 hpi while the foregut and cuticular epithelium were positive 18 hpi and the lymphoid organ and midgut were positive 21 hpi. The present study confirmed the replication of WSSV in P. monodon heart, antennal gland, foregut, stomach, gills, cuticular epithelium, hematopoietic tissue, connective tissue, and lymphoid organ.
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    Viral Infections of Macrobrachium spp.: Global Status of Outbreaks, Diagnosis, Surveillance, and Research
    (Israeli Journal of Aquaculture - BAMIGDEH, 2009) Hameed, A.S. Sahul
    Macrobrachium rosenbergii, a global and economically important cultured freshwater prawn, is farmed on a large scale in many countries. Compared to penaeid shrimps, M. rosenbergii is a moderately disease-resistant species. However, viruses such as Macrobrachium hepatopancreatic parvo-like virus (MHPV), Macrobrachium muscle virus (MMV), infectious hypodermal and hematopoietic necrosis virus (IHHNV), white spot syn- drome virus (WSSV), Macrobrachium rosenbergii nodavirus (MrNV), and extra small virus-like particle (XSV) have been reported and are responsi- ble for economic losses to freshwater prawn culture. MrNV and XSV, the causes of white tail disease (WTD), have been reported as dangerous viruses to M. rosenbergii, resulting in 100% mortality in postlarvae and juve- niles within five days of infection. Clinical signs of WTD include lethargy and opaqueness of the abdominal muscle. Various aspects of WTD are dis- cussed in this paper, including tissue tropism of the causative viruses, host range, virus structure, vertical transmission, pathogenicity, and the possibil- ity of multiplying MrNV and XSV in a mosquito cell line.
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    Current Status of Viral Diseases in Asian Shrimp Aquaculture
    (Israeli Journal of Aquaculture - BAMIGDEH, 2009) Flegel, T.W.
    The giant or black tiger shrimp, Penaeus monodon, was formerly the dom- inant cultured shrimp species in Asia. Since approximately 2002, it has been essentially replaced by the domesticated American whiteleg shrimp P. vannamei. The change in dominant species has affected disease concerns. For both species, white spot syndrome virus (WSSV) and yellow head virus (YHV) are the most lethal. For P. monodon, the next most important dis- eases are hepatopancreatic parvovirus (HPV) and monodon baculovirus (MBV). For P. vannamei, they are taura syndrome virus (TSV) and infec- tious hypodermal and hematopoietic necrosis virus (IHHNV). TSV was introduced to Asia in 1998 by careless importation of shrimp stocks for aquaculture but has not been reported to cause problems with local crus- tacean species. IHHNV, which is endemic in Asia, is harmless to P. mon- odon but poses a constant threat to IHHNV-free stocks of P. vannamei if they are hatched and reared in Asia under non-biosecure conditions. An emerging disease for P. monodon is monodon slow growth syndrome (MSGS), a component of which seems to be Laem-Singh virus (LSNV). Infectious myonecrosis virus (IMNV) is a P. vannamei disease, first report- ed from Brazil but now reported in Indonesia where it was probably intro- duced by careless importation of shrimp aquaculture stocks. So far, IMNV has not been reported in other Asian countries. Penaeus vannamei nodavirus (PvNV) is a new pathogen first reported from Belize in 2004 with gross and histological signs that are indistinguishable from those of IMNV. The disease has not yet affected Asian culture. A more recent disease of P. vannamei in Asia is abdominal segment deformity disease (ASDD), possi- bly caused by a yet unknown local virus.
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    Hemorrhage Disease of Cultured Tra Catfish (Pangasianodon hypophthalmus) in Mekong Delta (Vietnam)
    (Israeli Journal of Aquaculture - BAMIGDEH, 2009) Ly, Loan Thi Thanh ; Nguyen, Du Ngoc ; Vo, Phuong Hong ; Doan, Cuong Van
    This study investigated hemorrhage disease in cultured tra catfish (Pangasianodon hypophthalmus) from An Giang, Ben Tre, Can Tho, and Vinh Long provinces in the Mekong Delta (Vietnam). The disease is characterized by internal organ necrosis, white (spot) nodules in the liver, kidney, and spleen, and petecchial hemorrhages on the tail, fins, and abdomen. Some fish have exophthalmus (pop eye), a reddish and swollen anus, and yellowish fluid in the peritoneal cavity. Moribund fish lose their appetite and swim at the sur- face. Bacteria isolated from the diseased fish consisted of Aeromonas hydrophila (38.8%), A. sobria (4.1%), A. caviae (2.0%), Edwardsiella ictaluri (4.1%), and a gram positive, anaerobic bacteria, Clostridium sp. (40.8%). Histological analyses showed necrotic cells and intranuclear, randomly- arranged, straight rod cells (1.0-1.5 x 3.0-4.0 μm) concentrated in the ulcers. Challenge test with A. hydrophila induced external signs of hemorrhagic dis- ease. Challenge test with Clostridium sp. confirmed the presence of the bac- teria in infected tissues with development of white nodules similar to those in naturally-infected fish. Fish challenged with E. ictaluri exhibited gas bubbles in the stomach and gut with a foul smell. Reovirus-like particles were seen by transmission electron microscopy. Further study is needed to determine the role of each pathogen alone and together with others in the pathogenesis of hemorrhage disease of tra catfish.
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    Surveillance of Emerging Fish Viral Pathogens in Some Southeast Asian Countries
    (Israeli Journal of Aquaculture - BAMIGDEH, 2009) Lio-Po, Gilda ; Amar, Edgar ; Peña, Leobert de la ; Orozco, Zenith Gaye ; Faisan, Joseph ; Suarnaba, Vonie ; Tubo, Delia Belle
    Preventing the transboundary movement of fish viral pathogens in a global environment requires active surveillance. This study examined the presence of three emerging viral pathogens among koi, common, grass, and silver carp in Cambodia, Lao PDR, Myanmar, Philippines, and Vietnam. The stud- ied viruses included koi herpesvirus (KHV), spring viremia of carp virus (SVCV), and grass carp reovirus (GCRV). Detection methods consisted of virus isolation by cell culture, infection assay in naive fish, polymerase chain reaction (PCR), and reverse-transcriptase PCR (RT-PCR). Tissues were collected and pooled from 193 fish samples in Dec. 2004 to Feb. 2005, 406 in Sep. 2005 to Feb. 2006, and 1302 in Oct. 2006 to Feb. 2007. For cell cul- ture, tissue filtrates were prepared from pooled spleens, kidneys, livers, and gills and inoculated onto koi fin (KF-1), grass carp kidney (GCK), and fat head minnow (FHM) cells. For infection assay, tissue filtrates were injected intraperitoneally to healthy, naive common carp. No virus was detected after three cell culture passages and the infection bioassays. One-step and nest- ed-step PCR was used to detect KHV in gills of fish samples. One-step and semi-nested RT-PCR was used to detect SVCV and GCRV in the spleens, kidneys, and livers of fish samples. Samples from all three years from all five countries yielded negative results for all three viruses, indicating that KHV, SVCV, and GCRV were not present in these five countries during the period of the study although KHV outbreaks had been detected in Indonesia, Taiwan, Japan, Thailand, China, and Malaysia.
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    Current Knowledge on Viral Nervous Necrosis (VNN) and its Causative Betanodaviruses
    (Israeli Journal of Aquaculture - BAMIGDEH, 2009) Nakai, T. ; Sugaya, T. ; Nishioka, T. ; Mushiake, K. ; Yamashita, H.
    Viral nervous necrosis (VNN) or viral encephalopathy and retinopathy (VER) caused by betanodaviruses (Nodaviridae) has seriously damaged global marine aquaculture since its first appearance in the late 1980s. In the past two decades, more than 100 papers have been published on the dis- ease. Although information is still limited, we now have more knowledge on the taxonomic position and molecular characteristics of betanodaviruses, and on the diagnosis, control, and infection mechanisms of the disease. This paper briefly reviews studies on VNN and betanodaviruses.
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    Hemorrhagic Disease of Grass Carp: Status of Outbreaks, Diagnosis, Surveillance, and Research
    (Israeli Journal of Aquaculture - BAMIGDEH, 2009) Jiang, Yulin
    Hemorrhagic disease of grass carp is the most serious infectious disease of grass carp and causes significant losses of fingerlings. The main clinical signs are external and internal hemorrhage. The disease is caused by aquareovirus and has several serotypes. The optimal epidemic temperature of this disease is 25-28°C. The disease can be transmitted by water or par- asite bite. Susceptible hosts are grass and black carp. Other cyprinids are only carriers. Vaccination can control hemorrhagic disease of grass carp. An inactivated vaccine prepared from organs of sick fish is simple and easy to produce with good efficacy. In China, hemorrhagic disease of grass carp was prevalent but has been controlled by wide application of the vaccine. In other Southeast Asian countries, it is a new disease. For surveillance and diagnosis of hemorrhagic disease of grass carp, isolation of the virus using carp kidney (CK) cells and reverse transcriptase polymerase chain reaction (RT-PCR) are the main methods of detection.
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    Spring Viremia of Carp Virus (SVCV): Global Status of Outbreaks, Diagnosis, Surveillance, and Research
    (Israeli Journal of Aquaculture - BAMIGDEH, 2009) Goodwin, Andrew E.
    The spring viremia of carp virus (SVCV) is an OIE-listed rhabodovirus his- torically responsible for losses of cultured fish in Europe. Acute disease is associated with high mortality, especially in common carp Cyprinus carpio during their first spring season when water temperatures are 10-15°C. Mortality has been reported in other cyprinids and in the Wels catfish Siluris glanis. The disease is characterized by hemorrhages on the skin and bloody mucus in the intestine, clinical signs shared by other diseases including bacterial infections. In 2002, SVCV was detected on a large koi farm in the USA. The USA isolate was 98% identical to isolates associated with koi and goldfish imported from China, but distantly related to European strains. In spring 2002, a major SVCV kill of common carp occurred in Cedar Lake, Wisconsin. This isolate was also of the Asian type, as were subsequent isolates from wild and cultured fish in several states. In the USA, all infected farmed populations were destroyed and no additional iso- lates have been detected since 2004. One of the most critical aspects of SVCV diagnosis is to differentiate the disease from the koi herpesvirus (KHV). The most obvious difference is that KHV generally occurs in tem- peratures of 20-28°C while SVCV disease occurs below 18oC and com- monly at 10-15°C.