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The presence of endogenous viral elements (EVE) in the penaeid shrimp genome has been recently reported and suggested to be involved in the host recognition of viral invaders. Our previous report of a search for EVE of infectious hypodermal and haematopoietic necrosis virus (IHHNV‐EVE) in the Thai Penaeus monodon whole genome sequence project (GenBank accession no. JABERT000000000) confirmed the presence of three clusters of EVE derived from IHHNV in the shrimp genome. This study aimed to compare an immunohistochemistry method (IHC) and a PCR method to detect infectious IHHNV infection in shrimp. First, specimens collected from farms were checked for IHHNV using three PCR methods; two methods were recommended by WOAH (309 and 389 methods), and a newly established long‐range PCR for IHHNV (IHHNV‐LA PCR) targeting almost the whole genome (>90%) of IHHNV. Among 29 specimens tested, 24 specimens were positive for WOAH methods (at least one method). Among 24 WOAH‐positive specimens (WOAH+), there were 18 specimens with positive IHHNV‐LA PCR method (WOAH+/LA+), six specimens with negative IHHNV‐LA PCR method (WOAH+/LA−). Six specimens were negative for all methods (WOAH−/LA−). The positive signals detected by IHC method were found only in the specimens with WOAH+/LA+. The results suggest that the WOAH+/LA− specimens were not infected with IHHNV, and the positive WOAH method might result from the EVE‐IHHNV. The study recommends combining the IHHNV‐LA PCR method and IHC with positive PCR results from WOAH's recommended methods to confirm IHHNV infection. [ABSTRACT FROM AUTHOR]

Keywords: biosecurity; disease; indonesia; production; records; shrimp aquaculture EN biosecurity disease indonesia production records shrimp aquaculture 1231 1236 6 07/15/22 20220801 NES 220801 INTRODUCTION Shrimp production yields and survival are affected by many factors, including environmental, farming methods and infectious diseases. Our study identified early emergence of production and salinity patterns related to clinical disease, and trends of pathogen detection and production indices related to biosecurity practices. Nevertheless, the results of this study can provide valuable guidance for future refinements of farm records in order to thoroughly investigate pertinent biosecurity practices for disease risk mitigation and enhanced production outcomes (Ali et al., 2018; Lotz, 1997; Munasinghe et al., 2010). [Extracted from the article]

Shrimps were intramuscularly injected with PBS, A. hydrophila, prestimulated with As-Cathelicidin4 and 24 hr later injected with A. hydrophila, or treated with As-Cathelicidin4 24 hr after infection with A. hydrophila. Keywords: antimicrobial peptides (AMPs); Cathelicidin; Exopalaemon modestus; host defence peptide; immune EN antimicrobial peptides (AMPs) Cathelicidin Exopalaemon modestus host defence peptide immune 743 754 12 04/08/22 20220501 NES 220501 INTRODUCTION An increase in antibiotic resistance has led to a pressing demand for an alternative strategy to fight infections. Shrimps were intramuscularly injected with PBS, A. hydrophila, prestimulated with As-Cathelicidin4 and 24 hr later injected with A. hydrophila, or treated with As-Cathelicidin4 24 hr after infection with A. hydrophila. Shrimps were intramuscularly injected with PBS, A. hydrophila, prestimulated with As-Cathelicidin4 and 24 hr later injected with A. hydrophila, or treated with As-Cathelicidin4 24 hr after infection with A. hydrophila. [Extracted from the article]

Vibriosis caused by luminous Vibrio species is one of the biggest challenges to shrimp industry in Bangladesh. This study aimed to characterize whole microbial communities from Vibrio‐infected black tiger shrimp (Penaeus monodon) using 16S rRNA‐based amplicon sequencing. A total of 36 disease‐free and infected shrimp were collected from six different hatcheries in Bagerhat, Bangladesh. A final pool of 12 samples (n = 6) was created by homogenization of the hepatopancreas samples from three shrimps collected from each hatchery for the same group. The amplicon sequencing data revealed significant (p <.05) decrease of alpha diversity measurements and subsequent effects (p <.05) on the hepatopancreas microbiota in the infected group, compared to control shrimp. Proteobateria and Aeromonas were the most dominant bacteria at phylum and genus level in both groups and identified as core microbiota in the community. Two bacterial groups at phyla level and eight at genus level were found associated with the alteration of hepatopancreas microbial communities and associated gene functions in vibriosis‐infected shrimp, revealed by differential abundance and KEGG pathway analysis. The overwhelming abundance of Citroibacter, Shewanella and Candidatus lineages in vibriosis‐infected shrimp needs further investigations. [ABSTRACT FROM AUTHOR]

The bunyavirus Mourilyan virus (MoV) occurs commonly in Black tiger (Penaeus monodon) and kuruma shrimp (Penaeus japonicus) farmed in eastern Australia. There is circumstantial evidence of MoV causing mortalities among P. japonicus moved from farm ponds to tanks for rearing as broodstock. To directly assess its pathogenic potential, independent cohorts of pond‐ (n = 24) or tank‐reared juvenile (n = 21) P. japonicus were challenged intramuscularly with a cephalothorax tissue homogenate of P. monodon containing high loads of MoV (1.48 ± 0.28 × 108 MoV RNA copies/µg total RNA). In each trial, mortalities accumulated gradually among the saline‐injected controls. Mortality onset occurred 12–14 days earlier in the pond‐reared shrimp, possibly due to them possessing low‐level pre‐existing MoV infections. Despite the time to onset of mortality differing, Kaplan–Meier survival analyses confirmed mortality rates to be significantly higher in both the pond‐ (p =.017) and tank‐reared shrimp (p =.031) challenged with MoV. RT‐qPCR data on shrimp sampled progressively over each trial showed high loads of MoV to establish following challenge and discounted GAV and other endemic viruses from contributing to mortality. Together, the data show that acute MoV infection can adversely compromise the survival of juvenile P. japonicus. [ABSTRACT FROM AUTHOR]

White spot syndrome virus ( WSSV), an enveloped double-stranded DNA virus, is the causative agent of a disease that has led to severe mortalities of cultured shrimps in Taiwan and many other countries. In the previous study, Penaeus monodon chitin-binding protein ( CBP) and glucose transporter 1 (Glut1), two cell membrane proteins, were found to at least interact with other 10 WSSV envelope proteins including VP51B. These envelope proteins might form a protein complex. According to the known information, VP51B was used to identify its role in the protein complex. Western blotting of the intact viral particles and fractionation of the viral components confirmed that VP51B is one of WSSV envelope proteins. In this study, the protein-protein interaction between VP51B and other WSSV envelope proteins was identified by far-western blot experiment and VP51B was found to interact with VP24, VP31, VP32, VP39B and VP41A. Furthermore, the in vivo neutralization experiment using recombinant VP51B plus with VP39B showed the best inhibition. These data indicate that VP51B participates in the WSSV protein complex and plays an important role in WSSV infection. [ABSTRACT FROM AUTHOR]

This study was conducted to test the effect of DnaK on priming immune responses in Penaeid shrimp. Juvenile-specific pathogen-free (SPF) P. vannamei shrimp were injected with 0.05 i g recombinant DnaK. One hour post-DnaK priming, a non-lethal dose of Vibrio campbellii (105 CFU shrimp- 1) was injected. Other treatments include only DnaK or V. campbellii injection or control with blank inocula. The haemolymph of three shrimp from each treatment was collected at 1.5, 6, 9 and 12 h post- DnaK priming (hpp). It was verified that injection with DnaK and V. campbellii challenge affected the transcription of 3 immune genes, transglutaminase- 1 (TGase-1), prophenoloxidase-2 (proPO-2) and endogenous HSP70 (lvHSP70). In P. monodon, shrimp were first injected with DnaK at a dose of 10 i g shrimp- 1 and one hour later with 106 CFU of V. harveyi (BB120) shrimp- 1 . Shrimp injected with DnaK showed a significant increase in proPO expression compared to the control (P < 0.05). Yet a double injection (DnaK and Vibrio) seemed to cause an antagonistic response at the level of expression, which was not equalled at the level of PO activity. Those results suggest that DnaK is able to modulate immune responses in P. vannamei and P. monodon. [ABSTRACT FROM AUTHOR]

The article discusses mortality in farmed oriental river prawn, Macrobrachium nipponense, in China related new reovirus isolation and identification. Topics include reportings about reovirus affecting marine crabs in China, crustacean reovirus affecting shrimp and prawns including white shrimp Penaeus vannamei, tiger prawn Penaeus monodon, and shrimp Palaemon elegans, and a combination of pathogenic, nutritional, physiological and environmental factors causing diseases in freshwater prawns.

The article discusses identification of the yellow head virus genotype 3 (YHV-3) in Penaeus monodon. Topics discussed include impact of the yellow head disease (YHD) on shrimp industry in China, usage of the Polymerase chain reaction (PCR) for detection and the diagnosis of acute hepatopancreatic necrosis disease.

The article presents a histopathological findings which reveals the innate response of white spot disease (WSD) among penaeus monodon shrimps under a semi-intenseive culture. It outlines the health damages of white spot syndrome virus (WSSV) including encapsulation, cell agglutination and nodule formation among crustaceans. It highlights the molecular information on the presence of clotting mechanism in shrimp cause by WSSV during the infection.

An attempt was made to determine the replication efficiency of hepatopancreatic parvo-like virus ( HPV) of shrimp in different organs of freshwater rice-field crab Paratelphusa hydrodomous ( Herbst) using bioassay, PCR, RT- PCR, ELISA, Western blot and q- PCR analyses. Another attempt was made to use this crab as an alternative to penaeid shrimp for the large-scale production of HPV. This crab was found to be highly susceptible to HPV by intramuscular injection. The systemic HPV infection was confirmed by PCR and Western blot analyses in freshwater crab. The expression of capsid protein gene in different organs of infected crab was revealed by RT- PCR analysis. Indirect ELISA was used to quantify the capsid protein in different organs of the crab. The copy number of HPV in different organs of the infected crab was quantified by q- PCR. The results revealed a steady decrease in CT values in different organs of the infected crab during the course of infection. The viral inoculum that was prepared from different organs of the infected crab caused significant mortality in post-larvae of tiger prawn, Penaeus monodon ( Fabricius). The results revealed that this rice-field crab could be used as an alternative host for HPV replication and also for large-scale production of HPV. [ABSTRACT FROM AUTHOR]

White spot disease ( WSD) caused by white spot syndrome virus ( WSSV) creates severe epizootics in shrimp aquaculture industry worldwide. Despite several efforts, no such permanent remedy was yet developed. Selective breeding using DNA markers would be a cost-effective strategy for long-term solution of this problem. In the present investigation, out of 30 random primers, only one primer produced a statistically significant ( P < 0.01) randomly amplified polymorphic DNA ( RAPD) marker of 502 bp, which provided a good discrimination between disease resistant and disease susceptible populations of Penaeus monodon from three geographical locations along the East coast of India. Because RAPD markers are dominant, a sequence characterized amplified region ( SCAR) marker was developed by cloning and sequencing of 502 bp RAPD fragment, which generates a single 457 bp DNA fragment after PCR amplification only in the disease resistant shrimps. Challenge experiment was also conducted to validate this 457 bp SCAR marker, and the results suggested that the WSSV loads were 2.25 × 103 fold higher in disease susceptible than that in disease resistant shrimps using real-time PCR. Therefore, this 457 bp DNA SCAR marker will be very valuable towards the development of disease-free shrimp aquaculture industry. [ABSTRACT FROM AUTHOR]

A flow-through immunoassay ( FTA), an improved version of immunodot, was developed using a nitrocellulose membrane baked onto adsorbent pads enclosed in a plastic cassette to detect white spot syndrome virus ( WSSV) in shrimp. Sharp purple dots developed with WSSV against the white background of the nitrocellulose membrane. The detection limits of WSSV by the FTA and immunodot were 0.312 and 1.2 μg mL−1 crude WSSV protein, respectively. The FTA could be completed in 8-10 min compared with 90 min for immunodot. The FTA was 100 times more sensitive than 1-step polymerase chain reaction ( PCR) and in between that of the 1- and 2-step PCR protocol recommended by the Office of International Epizootics ( OIE). In experimental, orally infected shrimp post-larvae, WSSV was first detected 14, 16 and 18 h post-infection (hpi) by FTA, immunodot and one-step PCR, respectively. The FTA detected WSSV 2 and 4 h earlier than immunodot and one-step PCR, respectively. The FTA was more sensitive (25/27) than one-step PCR (23/27) and immunodot (23/27) for the detection of WSSV from white spot disease outbreak ponds. The reagent components of the FTA were stable giving expected results for 6 m at 4-8 °C. The FTA is available as a rapid test kit called 'RapiDot' for the early detection of WSSV under field conditions. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated the link between an experimental evidence for white spot syndrome virus (WSSV) and a microsatellite DNA marker in the giant black tiger shrimp Penaeus monodon (Fabricius). The researchers monitored mortality and WSSV propagation. A significantly higher mortality among disease susceptible shrimps was found.

A survey on the presence of the viruses of two economically significant diseases, white spot syndrome virus ( WSSV) and monodon baculovirus ( MBV) in wild-collected Penaeus monodon broodstock, was conducted during different seasons of the year in two major coastal areas of southeast India. The broodstock were collected along the coast of Tamil Nadu and Andhra Pradesh during summer, premonsoon, monsoon and post-monsoon seasons for three consecutive years. A total of 7905 samples were collected and subjected to MBV screening, and 6709 samples that were screened as MBV negative were diagnosed for WSSV. MBV was detected using rapid malachite green staining and WSSV by nested polymerase chain reaction. Prevalence data of the viruses were analysed using the Epi Calc 2000 program at 95% confidence interval. Samples collected from the Andhra Pradesh coast displayed a slightly higher prevalence of WSSV and MBV infection than those collected from Tamil Nadu, although this difference was not statistically significant ( P > 005). In addition, it was found that the prevalence of both WSSV and MBV infections fluctuated according to season. Data on prevalence of these viruses in broodstock would be useful to develop strategies for shrimp health management along the southeast coast of India. [ABSTRACT FROM AUTHOR]

White spot syndrome virus ( WSSV) is the most important pathogen in shrimp farming systems worldwide including the Mekong Delta, Vietnam. The genome of WSSV is characterized by the presence of two major 'indel regions' found at ORF14/15 and ORF23/24 ( WSSV-Thailand) and three regions with variable number tandem repeats ( VNTR) located in ORF75, ORF94 and ORF125. In the current study, we investigated whether or not the number of repeat units in the VNTRs correlates with virus outbreak status and/or shrimp farming practice. We analysed 662 WSSV samples from individual WSSV-infected Penaeus monodon shrimp from 104 ponds collected from two important shrimp farming regions of the Mekong Delta: Ca Mau and Bac Lieu. Using this large data set and statistical analysis, we found that for ORF94 and ORF125, the mean number of repeat units ( RUs) in VNTRs was significantly lower in disease outbreak ponds than in non-outbreak ponds. Although a higher mean RU number was observed in the improved-extensive system than in the rice-shrimp or semi-intensive systems, these differences were not significant. VNTR sequences are thus not only useful markers for studying WSSV genotypes and populations, but specific VNTR variants also correlate with disease outbreaks in shrimp farming systems. [ABSTRACT FROM AUTHOR]

Shrimp cell lines are yet to be reported and this restricts the prospects of investigating the associated viral pathogens, especially white spot syndrome virus (WSSV). In this context, development of primary cell cultures from lymphoid organs was standardized. Poly- l-lysine-coated culture vessels enhanced growth of lymphoid cells, while the application of vertebrate growth factors did not, except insulin-like growth factor-1 (IGF-1). Susceptibility of the lymphoid cells to WSSV was confirmed by immunofluoresence assay using monoclonal antibody against the 28 kDa envelope protein of WSSV. Expression of viral and immune-related genes in WSSV-infected lymphoid cultures could be demonstrated by RT-PCR. This emphasizes the utility of lymphoid primary cell culture as a platform for research in virus-cell interaction, virus morphogenesis, up and downregulation of shrimp immune-related genes, and also for the discovery of novel drugs to combat WSSV in shrimp culture. [ABSTRACT FROM AUTHOR]

Gill-associated virus (GAV) was found to be associated with decreased prawn, Penaeus monodon, production when prawns from three farms ( n = 45 ponds, 1800 prawns) were monitored for GAV over the production season using a graded RT-nPCR. The grading system used was a visualization of either the outer or inner nested PCR products. Prevalence and loading of GAV were associated with disease severity. Ponds with a higher initial prevalence and a larger increase in GAV load over the production period suffered disease outbreaks. Ponds with low initial prevalence of GAV but a larger increase in prevalence and large increase in load over the production period suffered chronic disease with no disease outbreak identified, yet low production. However, the ponds with moderate to low initial prevalence of GAV with a low increase in prevalence and load of GAV over the production period incurred no disease outbreak and comparatively high production. Ponds with GAV prevalence greater than 75% at 1 month post-stocking should be considered for termination as they have a high probability (95%) of having a disease outbreak. Emergency harvest when a disease outbreak occurs will significantly limit mortality losses. [ABSTRACT FROM AUTHOR]

White spot disease is caused by a highly virulent pathogen, the white spot syndrome virus (WSSV). The disease is usually triggered by changes in environmental parameters causing severe losses to the shrimp industry. This study was undertaken to quantify the relative WSSV load in shrimp exposed to ammonia, using a TaqMan-based real-time PCR, and their subsequent susceptibility to WSSV. Shrimp were exposed to different levels of total ammonia nitrogen (TAN) (8.1, 3.8 and 1.1 mg L−1) for 10 days and challenged with WSSV by feeding WSSV-positive shrimp. WSSV was detected simultaneously in haemolymph, gills and pereopods at four hours post-infection. The TaqMan real-time PCR assay showed a highly dynamic detection limit that spanned over 6 log10 concentrations of DNA and high reproducibility (standard deviation 0.33-1.42) and small correlation of variability (CV) (1.89-3.85%). Shrimp exposed to ammonia had significantly higher ( P < 0.01) WSSV load compared to the positive control, which was not exposed to ammonia. Shrimp exposed to 8.1 mg L−1 of TAN had the highest ( P < 0.01) WSSV load in all three organs in comparison with those exposed to 3.8 and 1.1 mg L−1 of TAN. However, haemolymph had significantly higher ( P < 0.01) viral load compared to the gills and pereopods. Results showed that shrimp exposed to ammonia levels as low as 1.1 mg L−1 (TAN) had increased susceptibility to WSSV. [ABSTRACT FROM AUTHOR]

To detect genomic variation of white spot syndrome virus (WSSV) isolates from different geographical regions of India, the variable number of the tandem repeat (VNTR) region of the ORF 94 (Thailand WSSV isolate – GeneBank Accession No. ) was analysed using five specific sets of primers. Analysis of 70 WSSV-positive samples showed the presence of 14 different genotypes of WSSV with VNTRs ranging from 2 to 16 tandem repeats with the majority (85.47%) having 6–12 tandem repeats. Occurrence of different genotypes of WSSV was found to be neither correlated to any specific geographical region nor to the different growth stage of the tiger shrimp, Penaeus monodon. Pathogenicity studies conducted with 25 isolates of WSSV revealed the presence of virulent and avirulent strains of WSSV in Indian shrimp farms. However, an unambiguous link could not be established between the different genotypes and their virulence. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented relating to a study on clinical white spot disease status in Penaeus monodon.

Apoptosis is proposed to be a major cause of death in shrimp viral infections. From our previous study, an apoptosis-related gene, Pm-Alix, was identified from the black tiger shrimp. Its expression was high in defence-related tissues including haemocytes and the lymphoid organ. To clarify its possible role in shrimp, we used Pm-Alix as bait in a yeast two-hybrid analysis to search for Alix interacting proteins in shrimp. Two cDNA sequences discovered had homology to a predicted ubiquitin C of the purple sea urchin, Strongylocentrotus purpuratus, and to a guanylyl cyclase of the red swamp crayfish, Procambarus clarkii. In vitro pull-down assays confirmed positive interaction between Pm-Alix and both proteins. Tissue distribution analysis revealed that Pm-Alix and the two binding partners were widely expressed in various tissues but more highly expressed in haemocytes. However, no significant positive or negative correlation was found in the expression of these genes as shrimp approached morbidity and death after challenge with white spot syndrome virus. Thus, the results suggested that Alix and its interacting partners did not play a direct role related to shrimp death. [ABSTRACT FROM AUTHOR]

Yellow head virus (YHV) is known as a major pathogen in the black tiger shrimp, Penaeus ( Penaeus) monodon. It can also cause serious mortality in farmed whiteleg shrimp, Penaeus ( Litopenaeus) vannamei. However, there is no published information on the economic and/or production impact of the disease in P. vannamei. Shrimp with gross signs of YHV disease (faded body colour and 60–70% mortality) were observed in 20 study farms rearing P. vannamei in the central part of Thailand from the end of 2007 through early 2008. The estimated economic loss for these farms according to the Thai Animal Aquaculture Association was approximately US$3 million. Detailed sequence analysis of RT-PCR amplicons from shrimp in all the study ponds revealed the presence of YHV Type 1b (YHV-1b) alone (characterized by a 162-bp deletion in the ORF3 region encoding the structural gene for gp116) and the absence of YHV Type 1a (YHV-1a), the original YHV type reported from Thailand. Despite the large 162-bp deletion (= 54 deduced amino acids) in the gp116 structural gene, histopathology of YHV-1b infections was identical to that of YHV-1a infections, and electron microscopy revealed that YHV-1b virions were morphologically indistinguishable from those previously reported for YHV-1a. In addition, an existing commercial RT-PCR detection kit and an immunochromatographic test strip for the detection of YHV were proven to have been valid tests for both YHV-1b and YHV-1a. The source of the virus for these outbreaks was unlikely to have been the post-larvae used to stock the ponds, as they were derived from domesticated specific pathogen-free stocks free of YHV. Thus, it is possible that they originated from an unknown, natural reservoir. [ABSTRACT FROM AUTHOR]

A bacterium was isolated from the mid-gut of healthy black tiger shrimp, Penaeus monodon, based on a large zone of inhibition in mixed culture on solid medium. The isolate was a Gram-positive, motile spore former, with an optimum pH range for growth in tryptone soya broth containing 2% NaCl of between pH 6 and 9. The bacterium was highly salt tolerant with concentrations between 0% and 8% having no detrimental effect on growth. The isolate was identified as Bacillus pumilus based on physiological capabilities using the API50CHB and Biolog systems. Amplification and sequencing of the 16S rRNA gene followed by phylogenetic analysis confirmed its identity. The Bacillus pumilus isolate was strongly inhibitory against the marine bacterial pathogens Vibrio alginolyticus, V. mimicus and V. harveyi, and weakly inhibitory against V. parahaemolyticus in cross-streaking assays on solid medium. The organism was marginally self-inhibitory, and inhibited B. licheniformis and B. subtilis. The suitability of the B. pumilus isolate for use as a probiotic in farmed shrimp was further supported by the absence of any of the known B. cereus enterotoxin genes. Based on these in vitro results, in vivo safety and efficacy trials are underway to determine suitability of the novel strain as a commercial probiotic. [ABSTRACT FROM AUTHOR]

The article offers information on a research carried out on the fitness and virulence of different strains of White Spot Syndrome Virus (WSSV). As reported, WSSV is the only member of the monotypic family Nimaviridae and genus Whispovirus. It causes an epidemic among farmed shrimps as it has the ability to cause 100 percent mortality among them within 3-10 days. WSSV is a double-stranded DNA virus with a large circular genome which is said to be the largest genomes among animal viruses.

The article presents a study which proves that artemia is not a vector for monodon baculovirus (MBV) transmission to Penaeus monodon. MBV of penaeid shrimp has been associated with high mortalities in hatchery-reared larval, post-larval and early juvenile stages of Penaeus monodon and is believed to have originated in Taiwan. It is stated that MBV is pathogenic to several species of shrimp including Penaeus monodon Fabricius and Penaeus penicillatus. Furthermore, the principal clinical sign of MBV is the presence of single or multiple, generally spherical occlusion bodies in the midgut epithelial cells and hepatopancreas.

This study reports the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy between a reverse transcriptase-nested polymerase chain reaction (RT-nPCR) and an enzyme-linked immunosorbent assay (ELISA) for the detection of gill-associated virus (GAV) from a sample of 120 Penaeus monodon. Subsequently, the same comparisons were applied to the ELISA and haemagglutination (HA) assays for detection of GAV from a second 120 prawns. The optical density (OD) or dilution cut-off point had a direct influence on the tested parameters. The cut-off OD of 0.5–0.6 with the ELISA produced a sensitivity of 98% compared with RT-nPCR. However, these OD produced the lowest accuracy (85.8% and 86.7%, respectively). The OD cut off of 0.75 resulted in the highest accuracy (91.7%) and NPV (81.3%) while it had the second highest sensitivity (97%) and PPV (93.3%). However, the OD cut off of 0.9 had the highest specificity (80%). With regards to HA, the titre cut off at 8 resulted in the highest sensitivity, specificity and NPV (94%, 100% and 100%, respectively) compared with the ELISA, while the HA titre of 16 gave the highest accuracy (73%) and the second highest specificity (75%). A HA titre of 64 gave the highest PPV (81%). Using the RT-nPCR as the gold standard, the ELISA had an accuracy of 91.7% when using a cut off >0.75 as a positive result. When compared with the ELISA, the HA had an accuracy of 73% when using an HA titre cut off greater than 16 as a positive result. These results indicate that alternative tests for GAV (ELISA and HA) can be used to explore multiple questions about the disease status of P. monodon stocks in a cost-effective manner. [ABSTRACT FROM AUTHOR]

Fusarium incarnatumwas isolated from gill lesions of cultured black tiger shrimp,Penaeus monodon, in every crop during 2000–2002 in Nghe An province, Vietnam. Infected shrimps showed typical signs of black gill disease and mortalities about a month prior to harvest. Detailed morphological examinations, as well as molecular phylogenic analyses based on partial nucleotide sequences of ribosomal DNA, were made on the isolates. An artificial infection of kuruma prawn,Penaeus japonicus, using two selected isolates was also conducted and their pathogenicity determined. [ABSTRACT FROM AUTHOR]

The VP28 gene of white spot syndrome virus (WSSV) was cloned into pRSET B expression vector. The VP28 protein was expressed as a protein with a 6-histidine taq inEscherichia coliGJ1158 with NaCl induction. Antiserum was raised against this recombinant-VP28 protein in rabbits and it recognized VP28 protein in naturally and experimentally WSSV-infected shrimp, marine crabs, freshwater prawns and freshwater crabs. The antiserum did not recognize any of the other known WSSV structural proteins. Various organs such as eyestalks, head muscle, gill tissue, heart tissue, haemolymph, tail tissue and appendages were found to be good materials for detection of WSSV using the antiserum and detection of WSSV was successful in experimentally infectedPenaeus monodonandP. indicusat 12 and 24 h post-infection (p.i.), respectively. The antiserum was capable of detecting WSSV in 5 ng of total haemolymph protein from WSSV-infected shrimp. [ABSTRACT FROM AUTHOR]

White spot syndrome virus (WSSV) isolated from Penaeus monodon was found to be highly infective for the western Mediterranean shrimp, Palaemon sp. Using polymerase chain reaction (PCR), it was demonstrated that such shrimp are not naturally carriers of WSSV. Following challenge with virus, mortality reached 100% 3.5–4 days after injection at 22 °C. Incubation of infected shrimp at 10 °C totally suppressed the mortality which rapidly developed when shrimp were returned to 18 or 22 °C. Preincubation of WSSV with mature synthetic mytilin significantly reduced shrimp mortality with a 50% efficient dose of about 5 μ m. Survival of shrimp was not due to the development of an active mechanism of defence as re-injection of WSSV produced the same mortality pattern. Mortality was probably due to WSSV replication as dot blot failed to detect viral DNA in the injection sample but was positive 1 day post-injection. Protection by mytilin was by interaction at the virus level, preventing replication as no WSSV nucleic acid was detected by PCR even after 7 days in shrimp injected with WSSV preincubated with 10 or 50 μ m mytilin. [ABSTRACT FROM AUTHOR]

Abstract The pathogenicity of white spot syndrome virus (WSSV) was tested with different developmental stages of Penaeus monodon , i.e. nauplius, protozoeae, mysis, early post-larvae (PL1-10), late post-larvae (PL11-20) and juveniles. WSSV challenge was done by immersion and oral routes. No disease occurred in the larvae and early post-larvae but they were positive for WSSV by nested polymerase chain reaction (PCR) assay. Significant mortality was observed in late post-larvae and juveniles and both single and nested PCR assays gave positive results with these samples. The results demonstrated that WSSV virulence in P. monodon increases with advancing stages of development and that WSSV infection does not result in disease for larvae and post-larvae younger than PL10. [ABSTRACT FROM AUTHOR]

White spot syndrome virus (WSSV) has been a major pathogen of cultured Penaeus monodon Fabricius in Malaysia since 1994. As quantitative study on the replication of WSSV is in its infancy, competitive polymerase chain reaction (PCR) was used for quantitative study of an experimental WSSV infection per os in growout P. monodon. Gills, abdominal integument and abdominal muscle were selected for viral quantification. Infection was detectable as early as 14 h postinfection (h p.i.) in both gills and integument, but the infection in muscle was only detected at 24 h p.i. Gill tissue had the highest viral load, followed by integument and muscle. Typical viral growth curves were obtained for all organs with distinct phases of eclipse (0–24 h p.i.), logarithmic (24–48 h p.i.) and the plateau (48–120 h p.i.). Cumulative mortality rapidly increased from 48 h p.i. and reached 100% at the end of the plateau phase at 120 h p.i. Gross signs of white spots and reddish discoloration were also obvious in moribund individuals from the plateau phase. Based on the three phases of viral growth, WSSV infection was classified into light, moderate and heavy infection stages. [ABSTRACT FROM AUTHOR]

Three hybridoma clones secreting monoclonal antibodies (MAbs) were produced from mouse myeloma and spleen cells immunized with white spot syndrome virus (WSSV) isolated and purified from Penaeus monodon (Fabricius), collected from north-eastern Taiwan. By sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE), the protein profile of this isolate contained four major proteins with sizes of approximately 35 (VP35), 28 (VP28), 24 (VP24), and 19 kDa (VP19). Western blot analysis revealed that two MAbs (1D7 and 6E1) recognized epitopes on VP28 and one MAb (3E8) recognized an epitope on VP19. The MAb 6E1 isotyped to the IgG1 class was used in both an indirect immunofluorescence assay (IFA) and in an immunochemical staining protocol for successful identification and localization of WSSV in infected shrimp tissues. Antigenic similarity of isolates from Indonesia and Malaysia to the Taiwan isolate was illustrated by IFA with MAb 6E1. A MAb (2F6) which bound specifically to two shrimp proteins, 75 and 72 kDa, and reacted to the healthy and non-target tissues of WSSV in infected shrimp, such as hepatopancreas, is also described here and shows the necessity for specific identification of antibodies. [ABSTRACT FROM AUTHOR]

The article discusses a study on the infection of cultured cells from the lymphoid organ of Penaeus monodon Fabricus and other penaeid shrimps by monodon-type baculovirus (MBV). Topics include the histopathological observation of MBV-infected shrimps, the susceptibility of culture cells to MBV, and research on the subcultivation in vitro of lymphoid tissue cells for the development of suitable cell lines for MBV culture.

This article presents a study of a reo-like virus observed in the tiger prawn, Penaeus monodon Fabricius, from Malaysia. In the spring and early summer of 1986, significant morbidity and mortality occurred among juvenile prawns, Penaeus monodon Fabricius, cultured in brackishwater grow-out ponds in the State of Johore, Malaysia. During the investigation specimens and tissue samples were taken for histopathology and electron microscopy. Hepatopancreas in semi-thin sections appeared vacuolated and contained a lot of pigment.