White spot syndrome virus (WSSV) transmission risk through infected cooked shrimp products assessed by polymerase chain reaction (PCR) and bio-inoculation studies

The aim of the study was to evaluate the resistance of white spot syndrome virus (WSSV) in shrimps (Penaeus monodon) to the process of cooking. The cooking was carried out at 1000C six different durations 5, 10, 15, 20, 25 and 30 min. The presence of WSSV was tested by single step and nested polymerase chain reaction (PCR). In the single step PCR, the primers 1s5 & 1a16 and IK1 & IK2 were used. While in the nested PCR, primers IK1 &IK2 – IK3 & IK4 were used for the detection of WSSV. WSSV was detected in the single step PCR with the primers 1s5 and 1a16 and the nested PCR with the primers IK1 and IK2 – IK3 & IK4 from the cooked shrimp samples. The cooked shrimps, which gave positive results for WSSV by PCR, were further confirmed for the viability of WSSV by conducting the bio-inoculation studies. Mortality (100%) was observed within 123 h of intra-muscular post injection (P.I) into the live healthy WSSV-free shrimps (P. monodon). These results show that the WSSV survive the cooking process and even infected cooked shrimp products may pose a transmission risk for WSSV to the native shrimp farming systems.

Rapid detection of white spot syndrome virus (WSSV) of Penaeus monodon by latex agglutination test using monoclonal antibodies

Latex beads were sensitized with monoclonal antibodies (MAb) rose against VP28 of WSSV. The optimum concentration of MAb required to sensitize the latex beads was 125 µg/ml. The sensitized latex beads were used to detect WSSV from PCR-positive stomach tissue homogenates obtained from infected shrimp. Stomach tissue homogenates from WSSV-infected shrimp agglutinated the sensitized latex beads within 10 minutes, while uninfected samples did not produce any agglutination, although non-specific agglutinations were observed in some samples. The analytical sensitivity, analytical specificity, diagnostic sensitivity and diagnostic specificity of the (LAT) agglutination test were assessed. The analytical sensitivity of the test was 40 ng of purified WSSV (2 µg/ml). The sensitized latex beads did not agglutinate with normal shrimp tissue or MBV-infected tissue homogenate. The test has a diagnostic sensitivity of 70 and 45%, respectively, compared to single-step and nested PCR. The diagnostic specificity of the test was 82%. This test is a simple and rapid on-farm test which can be used to corroborate clinical signs for the detection of WSSV in grow-out ponds.

Experimental pathogenecity of white spot syndrome virus (WSSV) in Litopenaeus vannamei

The pathogenecity of white spot syndrome virus (WSV) was studied experimentally with challenge exposure of two hundred shrimp with average weight 10 to 12 grams of Litopenaeus vannamei. The shrimp L. vannamei before introducing examined with IQ 2000 detection Kit for WSV. The Fenneropenaeus indicus that showed the clinical sign and PCR positive of white spot disease (WSD) was used the source of WSV. The challenge exposures were accomplished by feeding minced tissue of F. indicus for 24 hours. The result showed L. vannamei after three days revealed the clinical sign of WSV, the PCR examined was positive and all shrimp died after ten days. The shrimp that showed sign of disease were collected for histpathology in Davidson fixator and a part of samples preserved in Ethyl alcohol %75to %90 for PCR. The histopathology showed the effect of virus and cowdly type A inclusion body can see in all tissue except hepatopancreas. The PCR also indicate the virus infected the shrimp Litpeneaus vannamei after 3 days. The SOI and ROI determined the severity of infection and rate of infection in different tissue.

Protection of white leg shrimp (Litopenaeus vannamei) against white spot disease virus using oral recombinant bioencapsulated VP28

Aquaculture, is perceived as having the greatest potential to meet the growing demand for aquatic food. Crustaceans form one of the main value added components in aquaculture and among them, shrimp aquaculture is the predominant one. Industrial shrimp fanning, in combination with poor management in shrimp aquaculture, has quickly led to severe pollution in shrimp ponds, thereby creating a suitable environment for development of bacterial and virus diseases. White spot disease is one of the most deadly diseases that are caused heavy loss in all Penaeid shrimps family. In Iran during 2002 to 2004 in the Kuzestan province and in 2005 in Bushehr province, the most ponds and farms infected with white spot and the entire industry was facing threat of closure. Owing to the impact of WSSV infection to shrimp aquaculture, there is an urgent need to develop suitable strategies to protect cultured shrimps and make aquaculture more sustainable. Therefore, this study aimed to examine the possibility of protecting shrimp against white spot syndrome virus using bioencapsulated Anemia with E. coil containing the recombinant protein VP28, designed. Virus genome was extracted from naturally infected Litopenaeus vannamei in the Choebdch farms and VP28 gene by designed primers was amplified, extracted, purified and cloned in E. coli TGI. Protein expression evaluated and inactivated bacteria containing recombinant protein encapsulated in Artemia nauplii. White shrimp post larvae stage 5 were fed for 5 days with recombinant nauplii and twice on days 7 and 25 after feeding with Artemia nauplii were challenged with white spot virus. The results of the first experiment revealed that cumulative mortality percent in the group receiving the bacteria containing recombinant plasmid (pMal + VP28) was %14.44±1.11 and the relative percent survival %80.30±1.51. In this group the mortality rates in the various repetitions varied from the 13.33% to 16.66% and relative percent survival of 77.27% to 81.81%. in the Non-recombinant plasmid group (pMal) Mean percent mortality was% 33.33±3.84 and the Relative Percent Survival %54.54±5.24 and in the group that received bacteria contained no recombinant plasmid the Mean cumulative mortality percent was%48.88 ± 5.87 and Relative Percent Survival%33.33± 8.01.

Study of white spot disease in four native species in Persian Gulf by histopathology and PCR methods

After serious disease outbreak, caused by new virus (WSV), has been occurring among cultured penaeid shrimps in Asian countries like China since 1993 and then in Latin American countries, during June till July 2002 a rapid and high mortality in cultured Penaeus indicus in Abadan region located in south of Iran with typical signs and symptoms of White Spot Syndrome Virus was confirmed by different studies of Histopathology, PCR, TEM, Virology. This study was conducted for the purpose of determination of prevalence(rate of infection)/ROI and grading severity (SOI) of WSD to five species: 150 samples of captured shrimps and 90 samples of cultured ones; Penaeus indicus, P. semisulcatus, P. merguiensis, Parapenaopsis styliferus, and Metapenaeus affinis in 2005. 136 of 240 samples have shown clinical and macroscopical signs & symptoms including; white spots on carapase (0.5-2 mm), easily removing of cuticule, fragility of hepatopancreas and red color of motility limbs. Histopathological changes like specific intranuclear inclusion bodies (cowdry-type A) were observed in all target tissues (gill, epidermis, haemolymph and midgut) but not in hepatopancreas, among shrimps collected from various farms in the south and captured ones from Persian Gulf, even ones without clinical signs. ROI among species estimated, using the NATIVIDAD & LIGHTNER formula(1992b) and SOI were graded, using a generalized scheme for assigning a numerical qualitative value to severity grade of infection which was provided by LIGHTNER(1996), in consideration to histopathology and counting specific inclusion bodies in different stages(were modified by B. Gholamhoseini). Samples with clinical signs, showed grades more than 2. Most of the P. semisulcatus and M. affinis samples showed grade of 3, in the other hand in most of P. styliferus samples grade of 4 were observed, which can suggest different sensitivity of different species. All samples were tested by Nested PCR method with IQTm 2000 WSSV kit and 183 of 240 samples were positive and 3 1evel of infection which was shown in this PCR confirmed our SOI grades, but they were more specified.

White spot viral disease in penaeid shrimp: a review

The white spot viral disease in penaeid shrimp affects the development of the global shrimp industry. This paper reviews the viruses that cause the disease, the transmission of the virus, diagnosis and preventive measures.

Detection of viral diseases in shrimp Litopenaeus vannamei in Iran with emphasis on white spot disease prevention by using marine alga extract

Nowadays, following was expanded shrimp breeding and culture; viral diseases have been main problem which threatened shrimp industry in the country. Therefore, shrimp samples were obtained from different stages of Litopenaeus vannmei life cycle (larval, post larval, juveniles, adults and broodstocks) based on clinical signs in the breeding center and shrimp farming from Bushehr, Khozestan and Sistan and Baluchestan provinces. Viral diseases were detected by PCR (Polymerase Chain Reaction), histopathology and transmission electron microscopy (TEM) methods. Results of the PCR were indicated present white spot virus (WSV) in juveniles, sub adults and adults shrimp with medium intensity from three provinces, but it was not showed in larval and post larval stages. Histopathological sections were indicated hypertrophy and basophilic Cowdry type A formation in nucleus cells of gill, haematopoietic, lymphoid and epithelial's cuticles and intestinal tissues which was associated with small vacuoles increased in B cells of hepatopancreas tissue of infection shrimps. Transmission electronic microscopic studies were demonstrated that the length and diameter virus was detected, respectively, 300 ± 20 nm and 75 ± 5 nm. Considerable, results of the PCR were only displayed IHHNV in juvenile, adult and broodstock shrimps from breeding and farming center of Bushehr province. The main lesion pathology was formed eosinophilic Cowdry type A in nucleus cells of gill, haematopoietic, lymphoid and epithelial's cuticles and intestinal tissues. Whereas penaeid shrimps are lack specific immune system, hence, in the present study was used of marine alga (Lurensia snideria) collected from along costal Persian Gulf of Bushehr province for viral diseases were prevented. Powder alga extract were added with a ratio of 1 % to shrimp diet. Total haemocyte count (THC) and total protein plasma (TPP) were increased after 5 days of oral administration diets. When shrimps were infected by with spot virus experimentally, THC and TPP gradually were increased in both two groups (shrimps fed with diet containing alga extract and without alga extract) after 48h. Nevertheless; THC, TPP and survival of shrimp fed with diet containing alga extract were more than shrimp control in 15 days. So, oral administration Lurensia snideria extract was capable prevention infected L. vannamei via stimulant specific immune system.

Environmental parameters and incidence of white spot disease in Penaeus monodon (Fab.) farming

An investigation was carried out to monitor management practices and to find out whether there is any relationship with occurrence of deadly white spot disease and environmental parameters. Three semi-intensive and a improved traditional shrimp farms were selected in which mass mortality of shrimp (Penaeus monodon) by white spot disease occurred previously. The farms were situated at two different geographical locations. Two ponds from each farm at random were selected for the study. Out of eight investigated ponds, 6 ponds in three farms were affected by the disease during investigation period. The non-affected ponds had relatively lower stocking density, lightly different management practice and were located at different geographical area. There was no significant variation in water quality parameters among the affected and non-affected ponds. No significant variations were recorded in pond preparation, source of Post Larvae (PL), water and feed management among the affected and non-affected ponds. The observation indicated that pond micro-organisms in a farm may not the only cause of the disease but some external factors also might be responsible for the outbreak of this disease.

Pathogens after shrimp: A rogue's gallery of the industry's four most destructive adversaries

The paper discusses the four most destructive shrimp pathogens, such as MBV, the monodon baculovisrus, IHHNV, the infectious hypodermal and hematopoietic necrosis virus, Vibrio harveyi, the luminous bacteria, and WSBV, the white spot syndrome-associated baculovirus. The effects, detection method and treatment for the four pathogens were also briefly discussed.

Culture of prawn in rotation with shrimp

A progressive farmer in Tamil Nadu state, India experimented with crop rotation and successfully cultured Penaeus monodon during the dry season and Macrobrachium rosenbergii during the wet season. The details of M. rosenbergii culture are discussed in this article. Rotation with M. rosenbergii did help the farmer overcome the disease problem since farmers who exclusively cultured P. monodon in the nearby areas during the same season suffered losses due to white spot disease.

Disease problems in shrimp sector in Khulna district of Bangladesh: a question of sustainability

Disease is the main restraining factor for the development of shrimp sector in Bangladesh. Both brackish water shrimp bagda (Penaeus monodon) and freshwater prawn golda, (Macrobrachium rosenbergii) farming in Bangladesh have been facing disease problem. A study on disease outbreak in both brackish water and freshwater small-scale shrimp farms (gher) in Khulna district was carried out through interviewing randomly selected 3-5% of shrimp farmers with a structured questionnaire during March to December, 2002. The study showed that 97% bagda farming ghers and 80% golda farming ghers were affected by disease. White spot disease was the severe disease for bagda, whereas, antenna rot was the main disease for freshwater prawn. Change of water and liming were carried out as control measures of disease for bagda shrimp farming, while it was only liming for golda farming. A small number of shrimp farmers (15%) used chemicals for treatment of shrimp diseases. Development of suitable farming technology to prevent disease contamination and innovation of proper treatments for diseases are required to overcome the disease problems for sustainable shrimp farming in Bangladesh.

Health and disease status of Thai pangas, Pangasius hypophthalmus cultured in rural ponds of Mymensingh, Bangladesh

Thai pangas, Pangasius hypophthalmus is one of the important aquaculture species in Bangladesh. Over the last few years spectacular development has been taking place in Thai pangas farming in Mymensingh district. Due to availability of easy breeding and culture techniques as well as quick return, more and more people are converting their rice fields into pangas farms overnight. The present study was carried out to examine health and disease status of Thai pangas mainly through clinical, histopathological and bacteriological techniques. In addition, for collecting primary data on disease and health status of Thai pangas and the resultant socioeconomic impacts on rural households, questionnaire interview and participatory rural appraisal tools were used with selected farming households in three upazilas of Mymensingh district. The most prevalent diseases as reported by the farmers were red spot, followed by anal protrusion, tail and fin rot, pop eye, dropsy and gill rot. Other conditions like cotton wool type lesion, ulceration and white spot were reported but with lower incidence. Four isolates of Aeromonas hydrophila were recovered from kidney and lesion of diseased fish. Hemorrhage over the body especially near mouth and caudal region was noticed in the fishes associated with aeromonad infection. Internally, kidney, liver and spleen became swollen and enlarged. The isolates varied with their pathogenicity. All the four isolates were sensitive to Nitrofurantoin, Cotrimoxazole and Tetracycline but were resistant to Amoxycilline. An attempt was made to treat diseased fish with extracts from neem leaf, garlic and turmeric. Recovery of infection was monitored through mortality and histopathology. General histopathological changes of different organs were also studied. Extract from neem (Azadirachta indica) leaf gave better result. Telangiectasis, lamellar hypertrophy and hyperplasia hemorrhage, lamellar fusion, necrosis of lamellar epithelial cells, presence of parasites and their cysts were the major pathology of gills. Hemorrhagic lesion, pyknotic nuclei and melanomacrophage centers (MMC) were found in the liver of fish. Major pathologies in kidney of fish included presence of MMC, necrotic and ruptured kidney tubules, severe haemopoietic necrosis, and hemorrhage. The economic loss due to disease in Thai pangas farming was estimated from the difference between expected production and actual production. On an average, Thai pangas farmers of Mymensingh incur a loss of Tk. 23,104/ha/cycle due to fish disease (3.6% of expected total production). The loss, however, varied with location and size of farms, type of farmers and management practices. The study also highlighted fish health management related problems and recommended further work for the development of user-friendly farmer-oriented fish health management packages.

Southeast White Oak River shellfish restoration project

The 42-mile-long White Oak River is one of the last relatively unblemished watery jewels of the N.C. coast. The predominantly black water river meanders through Jones, Carteret and Onslow counties along the central N.C. coast, gradually widening as it flows past Swansboro and into the Atlantic Ocean. It drains almost 12,000 acres of estuaries -- saltwater marshes lined with cordgrass, narrow and impenetrable hardwood swamps and rare stands of red cedar that are flooded with wind tides. The lower portion of the river was so renowned for fat oysters and clams that in times past competing watermen came to blows over its bounty at places that now bear names like Battleground Rock. The lower river is also a designated primary nursery area for such commercially important species as shrimp, spot, Atlantic croaker, blue crabs, weakfish and southern flounder. But the river has been discovered. The permanent population along the lower White Oak increased by almost a third since 1990, and the amount of developed land increased 82 percent during the same period. With the growth have come bacteria. Since the late 1990s, much of the lower White Oak has been added to North Carolina’s list of impaired waters because of bacterial pollution. Forty-two percent of the rivers’ oyster and clam beds are permanently closed to shellfishing because of high bacteria levels. Fully two-thirds of the river’s shellfish beds are now permanently off limits or close temporarily after a moderate rain. State monitoring indicates that increased runoff from urbanization is the probable cause of the bacterial pollution. (PDF contains 4 pages)