What to Know About Vibrio vulnificus

This JAMA Patient Page describes Vibrio vulnificus infection, its signs and symptoms, diagnosis, treatment, and prevention strategies.

Identification and functional analysis of transforming growth factor-β type I receptor (TβR1) from Scylla paramamosain: The first evidence of TβR1 involved in development and innate immunity in crustaceans

The transforming growth factor-β (TGF-β) receptor-mediated TGF-β signaling cascade plays important roles in diverse cellular processes, including cell proliferation, differentiation, growth, apoptosis and inflammation in vertebrates. In the present study, the type I TGF-β receptor (TβR1) was firstly identified and characterized in mud crab Scylla paramamosain. The full-length cDNA of SpTβR1 was 1, 986 bp with a 1, 608 bp open reading frame, which encoded a putative protein of 535 amino acids including a typical transmembrane region, a conserved glycine-serine (GS) motif and a S_TKc domain (Serine/Threonine protein kinases, catalytic domain). Real-time PCR analysis showed that SpTβR1 was predominantly expressed at early embryonic development stage and was highly expressed at postmolt stages during molt cycle, suggesting its participation in development and growth. Moreover, the expression levels of SpTβR1 in hepatopancreas and hemocytes were positively induced after the challenges of Vibro alginolyticus and Poly (I:C), indicating the involvement of SpTβR1 in responding to both bacterial and viral infections. The in vivo RNA interference assays demonstrated that the expression levels of two NF-κB members (SpRelish and SpDorsal) and six antimicrobial peptide (AMP) genes (SpCrustin and SpALF2-6) were significantly suppressed when the SpTβR1 was silenced. Additionally, the expression levels of SpTβR1, SpRelish, SpDorsal and AMPs were consistently down-regulated or up-regulated when the primary cultured hemocytes were treated with TβR1 antagonist or agonist for 24 h. These results indicated that TβR1 not only contributed to the crabs' development and growth but also played vital role in the innate immunity of S. paramamosain, and it also provided new insights into the origin or evolution of TGF-β receptors in crustacean species and even in invertebrates.

Molecular cloning and functional characterization of a homolog of the transcriptional regulator CSL in Litopenaeus vannamei

The Notch signaling pathway transcriptional regulator, CSL (also called as CBF1, Suppressor of Hairless or Lag-1 in different species, generally designated as CSL1), is not only associated with cell proliferation and differentiation but also involved in tumorigenesis, inflammation and immune regulation in vertebrates. We recently showed that Notch signaling was involved in the immune response of Litopenaeus vannamei shrimp. However, as an important transcriptional regulator of this pathway, whether or not shrimp CSL was also involved in immune response had not been explored. Here, we cloned and characterized the CSL gene in L. vannamei (LvCSL), which has a 2271 bp open reading frame (ORF) encoding a putative protein of 756 amino acids, and contains two conserved Lag1-DNA bind as well as beta trefoil domains (BTD). LvCSL clustered with invertebrates in the phylogenetic tree and closely related to the RBP Jk X1 of Parasteatoda tepidariorum. The transcript level of LvCSL analyzed by quantitative polymerase chain reaction (qPCR) showed that LvCSL was widely expressed in all tissues tested, with induced levels observed in the hepatopancreas and hemocytes following immune challenge with Vibrio parahaemolyticus, Streptoccocus iniae, lipopolysaccharide (LPS), and white spot syndrome virus (WSSV), therefore, suggesting LvCSL involvement in shrimp immune response to pathogens. Besides, LvCSL knockdown decreased the expression of proliferation-related genes (LvHey2 and LvAstakine), and attenuated the expression of immune-related genes L. vannamei hypoxia inducible factor alpha (LvHIF-α), LvLectin and L. vannamei small subunit hemocyanin (LvHMCS) in shrimp hemocytes, as well as significantly decreased total hemocyte count. Moreover, high cumulative mortality was observed in LvCSL depleted shrimp challenged with V. parahaemoliticus. In conclusion, our present data strongly suggest that LvCSL is an important factor in shrimp, vital for shrimp survival and contributing to immune resistance to pathogens.

Genomic structure and expression pattern of MHC IIα and IIβ genes reveal an unusual immune trait in lined seahorse Hippocampus erectus

The major histocompatibility complex (MHC) genes are crucial in the adaptive immune system, and the gene duplication of MHC in animals can generally result in immune flexibility. In this study, we found that the lined seahorse (Hippocampus erectus) has only one gene copy number (GCN) of MHC IIα and IIβ, which is different from that in other teleosts. Together with the lack of spleen and gut-associated lymphatic tissue (GALT), the seahorse may be referred to as having a partial but natural "immunodeficiency". Highly variable amino acid residues were found in the IIα and IIβ domains, especially in the α1 and β1 domains with 9.62% and 8.43% allelic variation, respectively. Site models revealed seven and ten positively selected positions in the α1 and β1 domains, respectively. Real-time PCR experiments showed high expression levels of the MHC II genes in intestine (In), gill (Gi) and trunk kidney (TK) and medium in muscle (Mu) and brood pouch (BP), and the expression levels were significantly up-regulated after bacterial infection. Specially, relative higher expression level of both MHC IIα and IIβ was found in Mu and BP when compared with other fish species, in which MHC II is expressed negligibly in Mu. These results indicate that apart from TK, Gi and In, MU and BP play an important role in the immune response against pathogens in the seahorse. In conclusion, high allelic variation and strong positive selection in PBR and relative higher expression in MU and BP are speculated to partly compensate for the immunodeficiency.

A controllable bacterial lysis system to enhance biological safety of live attenuated Vibrio anguillarum vaccine

Bacterial strains used as backbone for the generation of vaccine prototypes should exhibit an adequate and stable safety profile. Given the fact that live attenuated vaccines often contain some potential risks in virulence recovery and spread infections, new approaches are greatly needed to improve their biological safety. Here, a critically iron-regulated promoter PviuA was screened from Vibrio anguillarum, which was demonstrated to respond to iron-limitation signal both in vitro and in vivo. By using PviuA as a regulatory switch to control the expression of phage P22 lysis cassette 13-19-15, a novel in vivo inducible bacterial lysis system was established in V. anguillarum. This system was proved to be activated by iron-limitation signals and then effectively lyse V. anguillarum both in vitro and in vivo. Further, this controllable bacterial lysis system, after being transformed into a live attenuated V. anguillarum vaccine strain MVAV6203, was confirmed to significantly improve biological safety of the live attenuated vaccine without impairing its immune protection efficacy.

The impacts of handling and air exposure on immune parameters, gene expression, and susceptibility to vibriosis of European abalone Haliotis tuberculata

Wild or farmed abalone are regularly exposed to stressors, such as air exposure and handling. Immune and transcriptional responses as well as susceptibility to vibriosis of sexually mature or immature European abalone acclimated at 16 or 19 °C were determined following handling or air exposure. Hemocyte density and H2O2 production increased while hemocyte viability and phagocytic index decreased following handling. Air exposure induces a decrease of hemocyte density and phagocytic index. Measurement of the expression of genes implicated in general metabolic, immunological and stress responses in gills, foot-muscle and hemocytes by real time q-PCR suggested that both stressors lead to a metabolic rate depression, characterized by a general inhibition of transcription. Finally, following handling a Vibrio harveyi challenge enhances almost 100% mortality of sexually immature animals at 19 °C while it has been previously demonstrated that only mature are susceptible to vibriosis.

Activator protein-1 (AP-1) and response to pathogen infection in the Hong Kong oyster (Crassostrea hongkongensis)

Growing evidence suggests that the transcription factor activator protein-1 (AP-1), a downstream target of mitogen-activated protein kinase (MAPK) signaling, plays a major role in stimulating the synthesis of immune effector molecules during innate immune responses. We have characterized ChAP-1, an AP-1-like protein in Crassostrea hongkongensis that is a member of the AP-1 family of proteins. ChAP-1 is composed of 290 amino acid residues with a Jun and bZIP domain at the N- and C-termini, respectively, a structure similar to that of known Ap-1 proteins. ChAP-1 mRNA is expressed in several tissues analyzed, with highest expression in the mantle. Expression of ChAP-1 increases in response to Vibrio alginolyticus, Salmo haemolyticus or Salmo cerevisiae infection and, despite the location of GFP-tagged full-length ChAP-1 protein in the cytoplasm, ChAP-1 activates the transcription of an L8G5-luc reporter gene, and its over-expression can also activate the AP-1-Luc reporter gene in HEK293T cells.

Administration of Bacillus subtilis strains in the rearing water enhances the water quality, growth performance, immune response, and resistance against Vibrio harveyi infection in juvenile white shrimp, Litopenaeus vannamei

In this study, vegetative cell suspensions of two Bacillus subtilis strains, L10 and G1 in equal proportions, was administered at two different doses 10(5) (BM5) and 10(8) (BM8) CFU ml(-1) in the rearing water of shrimp (Litopenaeus vannamei) for eight weeks. Both probiotic groups showed a significant reduction of ammonia, nitrite and nitrate ions under in vitro and in vivo conditions. In comparison to untreated control group, final weight, weight gain, specific growth rate (SGR), food conversion ratio (FCR) and digestive enzymatic activity were significantly greater in the BM5 and BM8 groups. Significant differences for survival were recorded in the BM8 group as compared to the control. Eight weeks after the start of experiment, shrimp were challenged with Vibrio harveyi. Statistical analysis revealed significant differences in shrimp survival between probiotic and control groups. Cumulative mortality of the control group was 80%, whereas cumulative mortality of the shrimp that had been given probiotics was 36.7% with MB8 and 50% with MB5. Subsequently, real-time RT-PCR was employed to determine the mRNA levels of prophenoloxidase (proPO), peroxinectin (PE), lipopolysaccharide- and β-1,3-glucan- binding protein (LGBP) and serine protein (SP). The expression of all immune-related genes studied was only significantly up-regulated in the BM5 group compared to the BM8 and control groups. These results suggest that administration of B. subtilis strains in the rearing water confers beneficial effects for shrimp aquaculture, considering water quality, growth performance, digestive enzymatic activity, immune response and disease resistance.

The protein expression profile in hepatopancreas of scallop Chlamys farreri under heat stress and Vibrio anguillarum challenge

Heat stress and pathogen infection have been considered as the main causes for mass mortality of cultured scallops during summer. In the present study, the expression profiles of proteins in the hepatopancreas of scallop Chlamys farreri were examined to reveal the possible mechanisms of physiological responses of scallop beneath heat stress and bacterial infection. An earlier occurred and higher mortality was observed in the scallops from combination treated group (28 °C and an injection of Vibrio anguillarum) in comparison to those in heat stress (28 °C) and bacteria challenge (V. anguillarum injection only) group, as well as control (PBS) and blank (untreated) group. The proteins in the hepatopancreas from scallops post 6 h of treatment were analyzed by using 2-D PAGE and ImageMaster 2D Platinum. There were total 1003 spots detected in control group, 1193 spots in heat stress group, 1263 spots in bacteria challenge group, and 1241 spots in the combination group. Fifteen protein spots expressed differentially between the combination treatment group and the bacteria challenge group were successfully identified by mass spectrometry and they were mainly classified as binding and catalytic proteins, such as endoglucanase, methylmalonate-semialdehyde dehydrogenase, xylose isomerase, tryptophanyl-tRNA synthetase, 40s ribosomal protein SA, glutathione S-transferase 4, and Mitochondrial transcription factor A, etc. These results indicated that the mortality of scallops suffered from the combination treatment was probably attributed to the impaired modulation of digestion and metabolism and ruined protein synthesis caused by heat stress together with bacteria infection. These data also provided valuable insights into the possible mechanisms of summer mortality occurrence of scallop at protein level.

A novel ortholog of serum response factor (SRF) with immune defense function identified in Crassostrea hongkongensis

Serum response factor (SRF) function is essential for transcriptional regulation of numerous growth-factor-inducible genes and triggers proliferation, differentiation and apoptosis of the cells. In this report, the first mollusk serum response factor like homolog gene (designated ChSRF) was identified and characterized from the Hong Kong oyster, Crassostrea hongkongensis. The full-length cDNA of ChSRF was 1716 bp in length and encodes a putative protein of 434 amino acids respectively, and shares the MADS domain at the N-terminal. ChSRF is ubiquitously expressed in various tissues, with the highest expression level observed in muscle. Temporal expression of ChSRF following microbe infection shows that the expression of ChSRF in hemocytes increases from 3 to 24 h post-challenge. As a target gene of SRF, β-actin demonstrates a similar gene expression mode in constitutive tissue and pathogen infection. Furthermore, some protein profiles of ChSRF was revealed, fluorescence microscopy results show that ChSRF located in the nuclei of HeLa cells and over-expression of ChSRF activated the transcriptional activities of MAPK signal pathway in HEK293T cells. These results indicate that ChSRF maybe play an important role in signal transduction in the immunity and development response of oysters. Furthermore, we found that ChSRF could regulate the expression of β-actin gene, which indicate that ChSRF is a muscle differentiation regulator in the oyster and it will help us to improve aquaculture production.

Cloning and characterization of a sialic acid binding lectins (SABL) from Manila clam Venerupis philippinarum

Sialic acid binding lectin (SABL) is a member of immunoglobulin-like lectins family that are thought to promote cell-cell interactions and regulate the functions of cells in the innate and adaptive immune systems through glycan recognition. In the present study, the full-length cDNA of SABL was identified from Manila clam Venerupis philippinarum (denoted as VpSABL) by cDNA library and RACE approaches. The cDNA of VpSABL consisted of a 5'terminal untranslated region (UTR) of 62 bp, a 3' UTR of 354 bp with a poly (A) tail, and an open reading frame (ORF) of 588 bp encoding a polypeptide of 195 amino acids with a typical C1q domain in the C-terminus. Multiple alignment analysis indicated that the deduced amino acid of VpSABL shared higher positive to other SABLs and C1q-contained proteins and should be adopted typical 10 β-strand jelly-roll folding topology common to all C1q-TNF family. Spatial expression analysis indicated that mRNA transcript of VpSABL was predominantly detectable in tissues of mantle, hepatopancreas and gill, and to a lesser degree in the tissues of muscle and haemocytes. After challenged by Vibrio anguillarum, the mRNA level of VpSABL in overall haemocytes population was recorded by quantitative real-time RT-PCR. VpSABL mRNA was down-regulated in the first 24 h post-infection. Then, the expression level increased to the peak at 72 h and recovered to the original level at 96 h. All these results indicated that VpSABL was involved in the immune response against microbe infection and might be contributed to the recognition of bacterial pathogens.

Summer immune depression associated with increased susceptibility of the European abalone, Haliotis tuberculata to Vibrio harveyi infection

Haliotis tuberculata mortality outbreaks have occurred in France since 1998 and were attributed to a pathogenic Vibrio harveyi. These mortalities were recorded in September, a month with abalone reproduction and characterised by high seawater temperatures. The importance of gonadal maturation and temperature increase on abalone immunity and susceptibility to V. harveyi infection needed to be clarified. Therefore, an immune survey analyzing a large panel of parameters was performed from June to September 2007 on abalone from the Bay of Brest. The data obtained were put in relation with abalone reproductive status and its susceptibility to V. harveyi. Most parameters showed clear patterns from early to late summer and during gametogenesis, phagocytosis and phenoloxidase activity were reduced, whereas basal reactive oxygen species production and agglutination titres were significantly increased. Total haemocyte counts went up after the partial spawning event at the end of June, and cell complexity diminished. Using a Principal Component Analysis, the "haemolymph profile" was shown to decrease in parallel with spawning and gonadal maturation processes, and reached a minimum just after total spawning. A significant correlation between this "haemolymph profile" and disease susceptibility allowed us to establish for the first time in abalone, a clear concordance between maturation and spawning processes, immune status and abalone susceptibility to V. harveyi.

Genetic variation in the Vibrio vulnificus group 1 capsular polysaccharide operon

Vibrio vulnificus produces human disease associated with raw-oyster consumption or wound infections, but fatalities are limited to persons with chronic underlying illness. Capsular polysaccharide (CPS) is required for virulence, and CPS expression correlates with opaque (Op) colonies that show "phase variation" to avirulent translucent (Tr) phenotypes with reduced CPS. The results discussed here confirmed homology of a V. vulnificus CPS locus to the group 1 CPS operon in Escherichia coli. However, two distinct V. vulnificus genotypes or alleles were associated with the operon, and they diverged at sequences encoding hypothetical proteins and also at unique, intergenic repetitive DNA elements. Phase variation was examined under conditions that promoted high-frequency transition of Op to Tr forms. Recovery of Tr isolates in these experiments showed multiple genotypes, which were designated TR1, TR2, and TR3: CPS operons of TR1 isolates were identical to the Op parent, and cells remained phase variable but expressed reduced CPS. TR2 and TR3 showed deletion mutations in one (wzb) or multiple genes, respectively, and deletion mutants were acapsular and locked in the Tr phase. Complementation in trans restored the Op phenotype in strains with the wzb deletion mutation. Allelic variation in repetitive elements determined the locations, rates, and extents of deletion mutations. Thus, different mechanisms are responsible for reversible phase variation in CPS expression versus genetic deletions in the CPS operon of V. vulnificus. Repetitive-element-mediated deletion mutations were highly conserved within the species and are likely to promote survival in estuarine environments.

A rapid and simple PCR analysis indicates there are two subgroups of Vibrio vulnificus which correlate with clinical or environmental isolation

Vibrio vulnificus is an estuarine bacterium which is the causative agent of both food-borne disease and wound infection. Although V. vulnificus is commonly found in molluscan shellfish at high numbers, the incidence of disease is relatively low, leading to the hypothesis that not all strains of V. vulnificus are equally virulent. Unfortunately, there is currently no easy test to identify virulent strains of this species. We have previously identified a 200 bp randomly amplified polymorphic DNA (RAPD) PCR amplicon associated with clinical isolates. DNA sequence data from this locus in six clinical and four environmental isolates showed that the strains could be divided into two groups, which we termed C-type (correlates with clinical origin) and E-type (correlates with environmental origin). We designed PCR primers that could distinguish between the two groups, and typed 55 randomly selected strains. We found that 90% of the C-type strains were clinical isolates, while 93% of environmental isolates were classified as E-type. The region directly downstream of this locus contained a heptanucleotide sequence repeated various times depending on the strain. Using a PCR-based assay to detect the repeat number present in a given strain, we found a statistically significant correlation with the C/E type classification and the number of repeats. The data reported here are consistent with the existence of two genotypes of V. vulnificus, with the C-type being a strong indicator of potential virulence.

Identification of genes that are differentially expressed in hemocytes of the Pacific blue shrimp (Litopenaeus stylirostris) surviving an infection withVibrio penaeicida

Considerable progress has been made in the field of invertebrate immunity through the characterization of genes involved in the response to infection and/or stress. However, the mechanisms by which commercially important marine invertebrates can successfully survive an infection remain largely unknown. For the first time in an invertebrate model, we have searched to discover genes involved in the survival capacity of shrimp using the highly pathogenic bacteria, Vibrio penaeicida. In the present study, we applied the technique of suppression subtractive hybridization (SSH) to hemocyte cDNAs from infected and uninfected shrimp, only using samples from individuals that had survived 96 h postinfection. The resulting library contains 260 expressed sequence tagged (EST) cDNA clones potentially representing highly expressed genes in surviving shrimp. Sequence similarity comparisons were made, and putative identities were assigned to clones that were at least 51% identical to known genes. This analysis showed two functional categories that were highly represented: those of genes involved in immune reactions (10.7% of the ESTs) and those involved in proliferation-hematopoiesis (10.3%). Expression pattern profile analyses of selected ESTs at different times postinfection confirmed the differential expression of the genes and efficiency of the SSH method. Differences in gene transcript abundance, for select ESTs encoding antimicrobial effectors, were evidenced by real-time PCR between shrimp that survived acute Vibrio infection and those individuals that did not survive acute Vibrio infection. These results suggest there are basic differences at the level of transcript abundance for genes directly involved in immune and hematopoietic processes from shrimp that survive and do not survive infection.

Genotypic analyses of Vibrio parahaemolyticus and development of a pandemic group-specific multiplex PCR assay

A total of 54 Vibrio parahaemolyticus strains including pandemic O3:K6 strains and newly emerged O4:K68, O1:K25, O1:K26, and O1:K untypeable strains (collectively referred to as the "pandemic group") were examined for their pulsed-field gel electrophoresis (PFGE) and arbitrarily primed PCR (AP-PCR) profiles and for the presence or absence of genetic marker DNA sequences, toxRS/new or orf8, that had been reported elsewhere to be specific for the pandemic group. Both PFGE and AP-PCR analyses indicated that all strains of the pandemic group formed a distinct genotypic cluster, suggesting that they originated from the same clone. In addition to the pandemic group, four O3:K6 strains that did not possess the thermostable direct hemolysin (tdh) gene also belonged to this cluster and possessed the toxRS/new sequence. However, three O3:K6 strains that clearly belonged to the pandemic group by PFGE and AP-PCR did not possess the orf8 sequence. The evidence suggests that neither the toxRS/new nor the orf8 sequence is a reliable gene marker for definite identification of the pandemic group. We therefore developed a novel multiplex PCR assay specific for the pandemic group. The assay successfully distinguished pandemic group strains from other V. parahaemolyticus strains by yielding two distinct PCR products for tdh (263 bp) and the toxRS/new sequence (651 bp).

PCR and molecular detection for differentiating Vibrio species

Vibriosis is an economically important disease of fish, marine invertebrates (particularly penaeid shrimps), and large marine mammals and is responsible for high mortality rates in aquaculture worldwide. Some Vibrio species are also responsible for zoonoses, whereas others are relatively nonpathogenic. Using 16S- and 23S-based PCR reactions, we obtained species-specific patterns and a 470-bp band, respectively. DNA sequences obtained on the 23S rRNA gene allowed us to identify species-specific probes for Vibrio parahaemolyticus, V. alginolyticus, V. anguillarum and for a cluster of taxonomically related species: V. carchariae/harveyi/campbelii. A phylogenetic tree based on the 23S sequences confirmed previous results obtained by Western blotting.

Chemical and serological properties of lipopolysaccharides from Vibrio parahaemolyticus O-untypeable strains isolated from patients

Chemical and serological studies have been carried out on the O-antigenic lipopolysaccharides (LPS) of six strains, U-6443, W-90144, X-3972, AD-7999, 90A-6611 and KX-V212, of Vibrio parahaemolyticus isolated from patients. The O-serotypes of these strains have not been identified because they were not agglutinated by any diagnostic antisera against known O-serotype strains. A compositional sugar analysis of their LPS revealed that out of the six O-untypeable (OUT) strains, U-6443, W-90144 and AD-7999 strains belonged to chemotype II (chemotype of O2), 90A-6611 and KX-V212 strains to chemotype III (chemotype of O3, O5, O11 and O13) and X-3972 strain to chemotype IV (chemotype of O4). A structural analysis of LPS isolated from KX-V212 revealed that the inner core region of the LPS consisted of only one mole of 2-keto-3-deoxy-D-manno-octonic acid, which carried a phosphate group at position C4 and the outer core at position C5. In passive hemolysis tests performed by using LPS as the antigen to sensitize sheep red blood cells (SRBC), and diagnostic antisera (O1 to O11) or anti-whole-cell rabbit antisera raised against O12, O13 and the six OUT strains, strong cross-reactivity was observed among LPS derived from the strains belonging to chemotype II (U-6443, W-90144, AD-7999 and O2). Strong cross-reactivity was also observed between X-3972 (chemotype IV) and O4 LPS. In contrast, LPS from two of the strains belonging to chemotype III (90A-6611 and KX-V212) did not react with any of the antisera raised against known O-serotypes. Cross-absorption tests showed that the O-antigens of U-6443, W-90144 and AD-7999 were identical to that of O2, and the O-antigen of X-3972 to that of O4. On the other hand, after the absorption of antisera raised against 90A-6611 and KX-V212 with O2 cells, the hemolytic activities against SRBC sensitized with homologous LPS were still retained at a high titer, whereas the hemolytic activities against SRBC sensitized with LPS from other O-serotype strains were completely eliminated. A cross-absorption test revealed that the O-antigens of these two strains were identical to each other. Thus, it was demonstrated that the O-serotype of OUT strains 90A-6611 and KX-V212 was not involved in the known O-serotypes; rather it represented a novel serotype which has not hitherto been reported.

Analysis of gyrB and toxR gene sequences of Vibrio hollisae and development of gyrB- and toxR-targeted PCR methods for isolation of V. hollisae from the environment and its identification

Isolation of Vibrio hollisae strains, particularly from the environment, is rare. This may be due, in part, to the difficulty encountered when using conventional biochemical tests to identify the microorganism. In this study, we evaluated whether two particular genes may be useful for the identification of V. hollisae. The two genes are presumed to be conserved among the bacterial species (gyrB) or among the species of the genus Vibrio (toxR). A portion of the gyrB sequence of V. hollisae was cloned by PCR using a set of degenerate primers. The sequence showed 80% identity with the corresponding Vibrio parahaemolyticus gyrB sequence. The toxR gene of V. hollisae was cloned utilizing a htpG gene probe derived from the V. parahaemolyticus htpG gene, which is known to be linked to the toxR gene in V. hollisae. The coding sequence of the cloned V. hollisae toxR gene had 59% identity with the V. parahaemolyticus toxR coding sequence. The results of DNA colony hybridization tests using the DNA probes derived from the two genes of V. hollisae indicated that these gene sequences could be utilized for differentiation of V. hollisae from other Vibrio species and from microorganisms found in marine fish. PCR methods targeting the two gene sequences were established. Both PCR methods were shown to specifically detect the respective target sequences of V. hollisae but not other organisms. A strain of V. hollisae added at a concentration of 1 to 10(2) CFU/ml to alkaline peptone water containing a seafood sample could be detected by a 4-h enrichment incubation in alkaline peptone water at 37 degrees C followed by quick DNA extraction with an extraction kit and 35-cycle PCR specific for the V. hollisae toxR gene. We conclude that screening of seafood samples by this 35-cycle, V. hollisae toxR-specific PCR, followed by isolation on a differential medium and identification by the above htpG- and toxR-targeted PCR methods, can be useful for isolation from the environment and identification of V. hollisae.

[A study on the distribution and etiology of pathogenic vibrio in the 5 coastal provinces of China]

In order to understand the distribution and pathogenicity of vibrio in the coastal areas of China a study consisted of 51 water samples and foodstuff from 10 different areas in 5 provinces was conducted microbiologically and etiologically. Results showed that 45 pathogenic vibrio were identified, with majority of A. caviae (26.7%), V. alginolyticus (22.2%) and V. parahaemolyticus (11.1%), same kinds of vibrio found in feces from patients with acute infectious diarrhea. Prevalence rates of pathogenic vibrio identified from the East China Sea, the South China Sea and the Yellow Sea were between 66%-77%. The detection rate of pathogenic vibrio in 29 water samples was 93.1% (27/29) with 38 strains isolated mainly in river water (57.8%), followed by in sea water (21.1%) and pool water (21.1%). The results revealed that the distribution of pathogenic vibrio in different waters was closely related to its pathogenecity, providing evidence that vibrio diarrhea be supervised, diagnosed and treated in order to decrease the incidence of the disease.