Vibrio Harveyi Strain Research Articles

Molecular Cloning and Bioinformatics Analysis of T3SS Inner Membrane Ring HrpQ from <i>Vibrio harveyi</i>

In this study, Vibrio harveyi strain HY99 was isolated from a diseased Epinephelus coioides . A full-length HrpQ gene of the bacteria was cloned and the amino acid sequence analyzed. The length of HrpQ gene sequence was 1,302 bp and coded 433 Amino acids. HrpQ relative molecular weight of theoretical prediction and isoelectric point were 48.002 kDa and 5.08 respectively. This protein was hydrophilic and there was one transmembrane region. There were three N-glycosylation sites. Structural analysis showed that the protein belonged to the FHA, Yop-YscD ppl superfamily. Secondary structure was composed of 31.41% α-helices, 21.71% extension chains, 7.16% beta turns and 39.72% random curls. The 3D structure of HrpQ protein was predicted to be a monomer similar to the 3D structure of the YscD putative type III secretion protein confirming that HrpQ is a T3SS protein and can be activated in vivo. This study provides a theoretical basis for further study on the function of HrpQ protein.

The high prevalence of pathogenic Vibrio harveyi with multiple antibiotic resistance in scale drop and muscle necrosis disease of the hybrid grouper, Epinephelus fuscoguttatus (♀) × E. lanceolatus (♂), in China.

Scale drop and muscle necrosis disease with high mortality widely occurred recently in the hybrid grouper (Epinephelus fuscoguttatus ♀×E.lanceolatus ♂), a crucial cultured marine fish species in China. In this study, 30 Harveyi clade isolates of 27 Vibrio harveyi strains were isolated from diseased hybrid groupers in the south-east and north-east coastal areas of China. A total of 22 V.harveyi strains were determined to be pathogenic, and most challenged fish died within 2days of infection; surviving individuals exhibited scale drop and deep dermal lesions as naturally diseased fish. Although five typical virulence genes, including luxR, toxRVh , chiA, serine protease and vhh widely existed in V.harveyi, no obvious correlation was established between virulent strains and virulence genes harboured in them. Furthermore, multiple antibiotic resistance was widely exhibited in Harveyi clade strains, particularly for penicillins, polypeptides, lincomycins, acetylspiramycin, streptomycin, metronidazole and bacitracin. And the multiple antibiotic resistance indices were gradually decreased from southern to northern areas of China. This study demonstrated that the pathogenic V.harveyi with multiple antibiotic resistance is highly prevalent in hybrid grouper in China, which requires particular attention.

In Vitro Biotransformation, Safety, and Chemopreventive Action of Novel 8-Methoxy-Purine-2,6-Dione Derivatives

Metabolic stability, mutagenicity, antimutagenicity, and the ability to scavenge free radicals of four novel 8-methoxy-purine-2,6-dione derivatives (compounds 1–4) demonstrating analgesic and anti-inflammatory properties were determined. Metabolic stability was evaluated in Cunninghamella and microsomal models, mutagenic and antimutagenic properties were assessed using the Ames and the Vibrio harveyi tests, and free radical scavenging activity was evaluated with 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. In the Cunninghamella model, compound 2 did not undergo any biotransformation; whereas 3 and 4 showed less metabolic stability: 1–9 and 53–88% of the parental compound, respectively, underwent biotransformation reactions in different Cunninghamella strains. The metabolites detected after the biotransformation of 3 and 4 were aromatic hydroxylation and N-dealkylation products. On the other hand, the N-dealkylation product was the only metabolite formed in microsome assay. Additionally, these derivatives do not possess mutagenic potential in microbiological models (Vibrio harveyi and Salmonella typhimurium) considered. Moreover, all compounds showed a strong chemopreventive activity in the modified Vibrio harveyi strains BB7X and BB7M. However, radical scavenging activity was not the mechanism which explained the observed chemopreventive activity.

Draft Genome Sequence of a Vibrio harveyi Strain Associated with Vibriosis in Pacific White Shrimp (Litopenaeus vannamei).

ABSTRACTVibrio harveyi is a Gram-negative bacterium associated with vibriosis in penaeid shrimp. Here, we report the draft genome sequence of a V. harveyi strain isolated from Pacific white shrimp (Litopenaeus vannamei) during a vibriosis outbreak. The availability of this genome will aid future studies of vibriosis in shrimp aquaculture.

Transferable chloramphenicol resistance determinant in luminous Vibrio harveyi from penaeid shrimp Penaeus monodon larvae

Antibiotic-resistant luminous Vibrio harveyi strains isolated from Penaeus monodon larvae were screened for the possession of transferable resistance determinants. All the strains were resistant to chloramphenicol and the determinant coding for chloramphenicol resistance was transferred to Escherichia coli at frequencies of 9.50x10-4 to 4.20x10-4. The results probably suggest the excessive use of chloramphenicol in shrimp hatcheries to combat luminous vibriosis.

Transferable chloramphenicol resistance determinant in luminous Vibrio harveyi from penaeid shrimp Penaeus monodon larvae

Antibiotic-resistant luminous Vibrio harveyi strains isolated from Penaeus monodon larvae were screened for the possession of transferable resistance determinants. All the strains were resistant to chloramphenicol and the determinant coding for chloramphenicol resistance was transferred to Escherichia coli at frequencies of 9.50x10-4 to 4.20x10-4. The results probably suggest the excessive use of chloramphenicol in shrimp hatcheries to combat luminous vibriosis.

Identification of pathogenicity, investigation of virulent gene distribution and development of a virulent strain-specific detection PCR method for Vibrio harveyi isolated from Hainan Province and Guangdong Province, China

A collection of 46 Vibrio harveyi strains were isolated from Epinephelus spp., Lutjanus erythopterus, and other maricultured fish in coastal areas of Hainan Province and Guangdong Province, China, between 2011 and 2013. Eighteen strains were determined to be pathogenic via artificial infection of healthy Epinephelus coioides at 107 colony-forming units (CFU) mL−1. Mortality occurred within 2 to 6h after injection. Genotypic assays of the 46 strains by enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) revealed a similar genotype profile, referred to as the ERIC-1 profile, for all 18 pathogenic strains. This finding indicates that pathogenic V. harveyi strains in south China have similar genetic backgrounds and might be representative pathogenic strains of this region. All 46 strains were screened for the presence of virulence genes typical of V. harveyi, of zoonotic Vibrio species such as V. cholerae, V. parahaemolyticus, and V. vulnificus and of the aquatic pathogen V. anguillarum. Virulence genes were amplified by PCR using specific primers, and five typical virulence genes of the Harveyi clade, luxR, toxRvh, chiA, serine protease and vhh, were detected in all pathogenic isolates. Non-pathogenic strains carried only 1 to 4 of these genes, indicating that these five genes might be the main virulence genes of ERIC-1 strains. Strain-specific PCR primers were designed based on the sequences of distinct ERIC-PCR bands for the 18 pathogenic strains. Species-specific primers exhibited high specificity and sensitivity. This study demonstrates that bacteria that are highly important to mariculture could be specifically detected using ERIC-PCR fingerprint-based amplification.

Seasonal variation in the antivibrio activity of two organic extracts from two red seaweed:Palmaria palmataand the introducedGrateloupia turuturuagainst the abalone pathogenVibrio harveyi

The wide polarity range and highly polar compounds of two selected red seaweed, Grateloupia turuturu and Palmaria palmata were extracted using two different types of solvent, dichloromethane/methanol and methanol/water. Monthly in vitro antibacterial activities were studied using the microplate method against the marine bacteria Vibrio harveyi strain ORM4, known to infect abalone. Inhibition, slowdown and delay of Vibrio harveyi growth were investigated. Polar compounds of seaweed showed an activity against the abalone pathogen. The best activity was recorded from P. palmata collected in spring, with an inhibition of 7.9% of the bacterial growth. Preliminary 1H NMR profiles identified the differences between the extracts.

Assessment of mutagenic, genotoxic, and cytotoxic potential of water samples of Harike wetland: a Ramsar site in India using different ex vivo biological systems.

Harike is a wetland of international importance under the Ramsar Convention. The present study entails the investigation of mutagenic, genotoxic and cytotoxic effect of surface water samples collected from five different areas of the Harike wetland by using the histidine reversion point mutation assay in Salmonella typhimurium (TA98 and TA100) strain with or without S9, bioluminescence mutagenicity assay using Vibrio harveyi (A16) strain, plasmid-nicking assay using pBR322 and 3(4,5-dimethyl-thiazol-2-yl)2,5-diphenyl-tetrazolium bromide assay as well as confocal imaging studies using Chinese hamster ovarian cell line, respectively. It was observed that although, the water sample of all the areas of wetland demonstrated mutagenic, genotoxic as well as cytotoxic activity, the effect was quite significant with the water samples from River Satluj and Khatan area (i.e. reservoir mainly contains Satluj water). The metal analysis of water samples was also conducted with atomic absorption spectrophotometer. The mutagenicity, genotoxicity and cytotoxicity of water samples emerged to be correlated with metal concentration. The source of toxic components seems to be associated with various industrial effluents and agricultural run-off. The results of the present study carry great importance in documenting the water quality monitoring data of the wetland.

Seasonal antibacterial activity of two red seaweeds,PalmariapalmataandGrateloupia turuturu, on European abalone pathogenVibrio harveyi

Vibrio harveyi is the main pathogen of the European abalone Haliotis tuberculata, and recently caused important mortalities at the production sites of this marine gastropod in France. In the present work, the monthly an- tibacterial activity of two red seaweed species from the French Atlantic coast, the native Palmaria palmata and the intro- duced Grateloupia turuturu, were investigated against the abalone pathogen Vibrio harveyi strain ORM4. Water-soluble extracts were screened using the microplate method. Grateloupia turuturu showed an antibacterial activity with a max- imal growth inhibition in spring of around 16%. In contrast, Palmaria palmata was inactive, as further growth of the bacteria was observed. Preliminary one-dimensional proton nuclear magnetic-resonance ( 1 H NMR) profiles identified the differences between the two water-soluble extracts.

In vitro biofilm forming capacity on abiotic contact surfaces by outbreak-associated Vibrio harveyi strains

Objective: To evaluate the in vitro biofilm forming capacity on abiotic food contact surfaces by Vibrio harveyi (V. harveyi) strains. Methods: Thirty six Gram-negative V. harveyi strains were isolated from various street vended seafood outlets in a food processing line and evaluated for their ability to produce mucoid biofilms on food contact surfaces using a microplate assay. Phenotypic characterization of mucoid biofilm producing V. harveyi strains were screened on Congo red agar, thiosulfate-citrate-bile salts-sucrose agar and tryptic soy agar, respectively. Results: Only five V. harveyi strains (14%) were mucoid biofilm producers characterized by formation of black colonies, whereas the remaining 31 strains (86%) were not capable of producing biofilm characterized by formation of red colonies or pinkish-red colonies with darkening at the centre. The morphological, physiological and biochemical characteristics of these isolates were studied using standard protocols. Strain identification was confirmed by polymerase chain reaction targeted to species-specific polymerase chain reaction primers VH-1 and VH-2 corresponding to variable regions of V. harveyi 16S rRNA sequence. All the biofilm-forming strains showed resistance to at least three antimicrobial compounds tested. V . harveyi strains isolated from various seafood were able to form biofilms of different capacity, and the strains VB267, VB238 and VB166 isolated from cat fish, shrimp and eel fish exhibited significantly greater biofilm forming ability compared to other isolates. Conclusions: It can be concluded from the present study that the strain VB166 was able to better attach and form subsequent biofilms on glass and stainless steel compared to high density polyethylene. These properties allow these bacteria to survive, proliferate and persist in street vended seafood outlets.

Single or combined effects of Lactobacillus sakei and inulin on growth, non-specific immunity and IgM expression in leopard grouper (Mycteroperca rosacea)

The aim of this study was to evaluate the single or combined effects of Lactobacillus sakei with inulin suitable for immunological in vivo studies in farmed fish. By in vitro assays, L. sakei strain 5-4 showed antibacterial activities against all assayed fish pathogens (except the Vibrio harveyi strain CAIM-1793). L. sakei was able to survive at high fish bile concentrations. Fermentation of the agave inulin resulted in a large increase in number of lactobacilli. For the in vivo study, fish were fed for 8 weeks four practical diets: control diet (control), L. sakei 5-4 (10(7) CFU/g), inulin (1% or 10 g/kg) and L. sakei + inulin (10(7) CFU/g + 10 g/kg). The weight gain showed clearly the synergistic effect of L. sakei 5-4 and inulin at 6 and 8 weeks of treatments. Leopard grouper fed with L. sakei alone or combined with inulin have significantly increased the assayed physiological and humoral immune parameters. By real-time PCR assays, the mRNA transcripts of immunoglobulin M (IgM) were found to be higher expressed in intestine, head kidney, mucus, gill, spleen and skin. Moreover, mRNA expression levels of IgM in head kidney and anterior intestine were measured by real-time PCR. L. sakei 5-4 and L. sakei + inulin supplemented diet up-regulated the expression of IgM at week 4 and 8 in intestine and head kidney, respectively. These results support the idea that the L. sakei 5-4 alone or combined with agave inulin improved growth performance and stimulates the immune system of leopard grouper.

Deciphering Bacterial Universal Language by Detecting the Quorum Sensing Signal, Autoinducer-2, with a Whole-Cell Sensing System

Bacteria communicate with neighboring bacteria of the same species or of other species by means of chemical signaling molecules. The concentration of such signaling molecules is proportional to the bacterial population size; upon reaching a threshold concentration, corresponding to a threshold cell density, certain specialized genes are expressed. This system of communication among bacteria is known as quorum sensing (QS). QS regulates diverse behaviors, such as formation of biofilms and production of pathogenic factors. Autoinducer-2 (AI-2) is a QS signaling molecule that is used for interspecies communication by both Gram-positive and Gram-negative bacteria. Bacteria are known to play an important role in many diseases, from infections to chronic inflammation. Therefore, QS is involved in a variety of disorders of bacterial origin or where bacteria play a crucial pathogenic role. One such condition is inflammatory bowel disease (IBD), a chronic inflammation of the gastrointestinal (GI) tract that includes debilitating diseases, such as ulcerative colitis (UC) and Crohn's disease (CD). To date, noninvasive methods are unavailable for the diagnosis and monitoring of IBD. We hypothesized that detection of QS molecules in physiological samples, specifically saliva and stool specimens, would provide with a method for the noninvasive, early diagnosis and monitoring of IBD conditions. To that end, we developed and optimized a whole-cell sensing system for AI-2, which is based on Vibrio harveyi strain BB170. Furthermore, we standardized and applied the biosensing system for the quantitative detection of AI-2 in saliva, stool, and intestinal samples from IBD patients.

English

Vibrio harveyi strains were isolated from the water samples of low salinity.  Isolates were confirmed by both the presence of vhh gene using polymerase chain reaction and bio-chemical tests.  V. harveyi was grown in LB medium and its spent culture was treated with ethyl acetate. The organic layer was pooled and dried by Roto - Vapour with vacuum at 30ËšC. The dried residues were dissolved with 50 % acetonitrile and water. The presence of N-acyl homoserine lactones (AHL) compounds from the residues of crude extract and the standard “3 - Oxo hexanoyl homoserine lactone” were analyzed separately using Liquid chromatography and mass spectrometry (LC-MS). Different peaks were detected and peaks corresponding to 214.4 m/z were identified as N- (3-oxohexanoyl)-L-homoserine lactones in the sample. Different unknown peaks were also identified.  Aqueous extracts of 47 terrestrial plants were evaluated against luminescence disease causing V. harveyi, through “Agar well diffusion assay”. Ten plant extracts showed zone of inhibition (5 to 7 mm) on V. harveyi. Extracts from Phyllanthus niruri and Cynodon dactylon showed the highest zone of inhibition (8.3 mm) against V. harveyi followed byCalotropis gigantean and Costus speciosus (7.3 mm). Plant extracts were reported for the presence of alkanes, alkenes, aromatics, primary and secondary amines etc, byFourier transform infra red spectroscopy (FT-IR). The antagonistic activity may be due to by the presence of these functional compounds in the extracts. Therefore, terrestrial plants could be used to control aquatic bacterial pathogens, which can also be extended to control human bacterial pathogens.   Key words: V. harveyi, extraction of N-acyl homoserine lactones (AHL), analysis by Liquid chromatography and mass spectrometry (LC-MS), terrestrial plants, antagonism,Fourier transform infra red spectroscopy.

Characterization of abalone Haliotis tuberculata–Vibrio harveyi interactions in gill primary cultures

The decline of European abalone Haliotis tuberculata populations has been associated with various pathogens including bacteria of the genus Vibrio. Following the summer mortality outbreaks reported in France between 1998 and 2000, Vibrio harveyi strains were isolated from moribund abalones, allowing in vivo and in vitro studies on the interactions between abalone H. tuberculata and V. harveyi. This work reports the development of primary cell cultures from abalone gill tissue, a target tissue for bacterial colonisation, and their use for in vitro study of host cell-V. harveyi interactions. Gill cells originated from four-day-old explant primary cultures were successfully sub-cultured in multi-well plates and maintained in vitro for up to 24days. Cytological parameters, cell morphology and viability were monitored over time using flow cytometry analysis and semi-quantitative assay (XTT). Then, gill cell cultures were used to investigate in vitro the interactions with V. harveyi. The effects of two bacterial strains were evaluated on gill cells: a pathogenic bacterial strain ORM4 which is responsible for abalone mortalities and LMG7890 which is a non-pathogenic strain. Cellular responses of gill cells exposed to increasing concentrations of bacteria were evaluated by measuring mitochondrial activity (XTT assay) and phenoloxidase activity, an enzyme which is strongly involved in immune response. The ability of gill cells to phagocyte GFP-tagged V. harveyi was evaluated by flow cytometry and gill cells-V. harveyi interactions were characterized using fluorescence microscopy and transmission electron microscopy. During phagocytosis process we evidenced that V. harveyi bacteria induced significant changes in gill cells metabolism and immune response. Together, the results showed that primary cell cultures from abalone gills are suitable for in vitro study of host-pathogen interactions, providing complementary assays to in vivo experiments.

Autoinducers Act as Biological Timers in Vibrio harveyi

Quorum sensing regulates cell density-dependent phenotypes and involves the synthesis, excretion and detection of so-called autoinducers. Vibrio harveyi strain ATCC BAA-1116 (recently reclassified as Vibrio campbellii), one of the best-characterized model organisms for the study of quorum sensing, produces and responds to three autoinducers. HAI-1, AI-2 and CAI-1 are recognized by different receptors, but all information is channeled into the same signaling cascade, which controls a specific set of genes. Here we examine temporal variations of availability and concentration of the three autoinducers in V. harveyi, and monitor the phenotypes they regulate, from the early exponential to the stationary growth phase in liquid culture. Specifically, the exponential growth phase is characterized by an increase in AI-2 and the induction of bioluminescence, while HAI-1 and CAI-1 are undetectable prior to the late exponential growth phase. CAI-1 activity reaches its maximum upon entry into stationary phase, while molar concentrations of AI-2 and HAI-1 become approximately equal. Similarly, autoinducer-dependent exoproteolytic activity increases at the transition into stationary phase. These findings are reflected in temporal alterations in expression of the luxR gene that encodes the master regulator LuxR, and of four autoinducer-regulated genes during growth. Moreover, in vitro phosphorylation assays reveal a tight correlation between the HAI-1/AI-2 ratio as input and levels of receptor-mediated phosphorylation of LuxU as output. Our study supports a model in which the combinations of autoinducers available, rather than cell density per se, determine the timing of various processes in V. harveyi populations.

A Nonluminescent and Highly Virulent Vibrio harveyi Strain Is Associated with “Bacterial White Tail Disease” of Litopenaeus vannamei Shrimp

Recurrent outbreaks of a disease in pond-cultured juvenile and subadult Litopenaeus vannamei shrimp in several districts in China remain an important problem in recent years. The disease was characterized by “white tail” and generally accompanied by mass mortalities. Based on data from the microscopical analyses, PCR detection and 16S rRNA sequencing, a new Vibrio harveyi strain (designated as strain HLB0905) was identified as the etiologic pathogen. The bacterial isolation and challenge tests demonstrated that the HLB0905 strain was nonluminescent but highly virulent. It could cause mass mortality in affected shrimp during a short time period with a low dose of infection. Meanwhile, the histopathological and electron microscopical analysis both showed that the HLB0905 strain could cause severe fiber cell damages and striated muscle necrosis by accumulating in the tail muscle of L. vannamei shrimp, which led the affected shrimp to exhibit white or opaque lesions in the tail. The typical sign was closely similar to that caused by infectious myonecrosis (IMN), white tail disease (WTD) or penaeid white tail disease (PWTD). To differentiate from such diseases as with a sign of “white tail” but of non-bacterial origin, the present disease was named as “bacterial white tail disease (BWTD)”. Present study revealed that, just like IMN and WTD, BWTD could also cause mass mortalities in pond-cultured shrimp. These results suggested that some bacterial strains are changing themselves from secondary to primary pathogens by enhancing their virulence in current shrimp aquaculture system.

LuxS distribution and AI-2 activity of Campylobacter spp.

This study investigates the distribution of LuxS within Campylobacter (Camp.) species and Autoinducer (AI)-2 activity of Camp. jejuni NCTC 11168 in food matrices. LuxS (S-ribosylhomocysteinase) sequences of different Campylobacter spp. were compared, and AI-2 activity was measured with an AI-2 reporter assay. Highest LuxS homologies were shared by Camp. jejuni, Camp. coli and Camp. upsaliensis, and their LuxS sequences had more similarities to the analysed Arcobacter and Vibrio harveyi strains than to all other analysed Campylobacter species. Of 15 analysed species only Camp. lari, Camp. peloridis and Camp. insulaenigrae did not produce AI-2 molecules. Cultivation of Camp. jejuni NCTC 11168 in chicken juice reduced AI-2 activity, and this reduction is not because of lower luxS expression or functionality. Not all Campylobacter species encode luxS. Food matrices can reduce AI-2 activity in a LuxS-independent manner. Besides, Camp. lari, Camp. peloridis and Camp. insulaenigrae do not show AI-2 activity. Further investigations should clarify the function of AI-2 in Campylobacter spp. and how species lacking luxS could overcome this alteration. Furthermore, the impact of food matrices on these functions needs to be determined as we could show that chicken juice reduced AI-2 activity.

Reducing Vibrio load in Artemia nauplii using antimicrobial photodynamic therapy: a promising strategy to reduce antibiotic application in shrimp larviculture

SummaryWe propose antimicrobial photodynamic therapy (aPDT) as an alternative strategy to reduce the use of antibiotics in shrimp larviculture systems. The growth of a multiple antibiotic resistant Vibrio harveyi strain was effectively controlled by treating the cells with Rose Bengal and photosensitizing for 30 min using a halogen lamp. This resulted in the death of > 50% of the cells within the first 10 min of exposure and the 50% reduction in the cell wall integrity after 30 min could be attributed to the destruction of outer membrane protein of V. harveyi by reactive oxygen intermediates produced during the photosensitization. Further, mesocosm experiments with V. harveyi and Artemia nauplii demonstrated that in 30 min, the aPDT could kill 78.9% and 91.2% of heterotrophic bacterial and Vibrio population respectively. In conclusion, the study demonstrated that aPDT with its rapid action and as yet unreported resistance development possibilities could be a propitious strategy to reduce the use of antibiotics in shrimp larviculture systems and thereby, avoid their hazardous effects on human health and the ecosystem at large.

‘Bright-red’ syndrome in Pacific white shrimp Litopenaeus vannamei is caused by Vibrio harveyi

Since July 2005, recurrent outbreaks of vibriosis have occurred in shrimp farms in northwestern Mexico. Moribund Litopenaeus vannamei associated with mass mortalities were lethargic and displayed red discoloration spots on their abdomen, and hence were called 'bright-reds' by farmers. Shrimp submitted for diagnosis were examined using wet tissue mounts, bacteriological assays and their respective minimum inhibitory concentration (MIC), and histology. A dominant yellow bacterial colony was isolated in thiosulphate citrate bile salts-sucrose (TCBS) agar and identified by molecular methods as Vibrio harveyi strain CAIM 1792. Pathogenicity of the V. harveyi strain was demonstrated in L. vannamei. The lowest MIC against Vibrio isolates from bright-red shrimp was obtained with enrofloxacine (3.01, SD = 5.96 pg ml(-1)). Histology detected severe necrosis in lymphoid organ tubules, muscle fibers, and connective tissue, as well as melanization and hemocytic nodules associate with microcolonies of Gram-negative bacilli. Bacteria from severely affected shrimp were dispersed from the haemocoel to other tissues causing a systemic vibriosis. The data indicate that V. harveyi strain CAIM 1792 is the cause of bright-red syndrome (BRS) and represents a threat to the Mexican shrimp farming industry.