Necrotising fasciitis with extensive necrosis caused by Lactobacillus: a case report.

BACKGROUND: Necrotising fasciitis (NF) is a life-threatening soft-tissue infection that rapidly destroys the epidermis, subcutaneous tissue, and fascia. Despite their low virulence, Lactobacillus spp. can cause NF, and because of its rare incidence, there is limited information about its molecular and clinicopathological characteristics. We report a rare case of NF in a patient with type 2 diabetes mellitus diagnosed on admission and severe obesity due to infection with two types of Lactobacillus spp. that manifested in extensive necrosis. CASE PRESENTATION: A 48-year-old woman was referred to our hospital with a complaint of difficulty walking due to severe bilateral thigh pain. She presented with mild erythema, swelling, and severe skin pain extending from the pubic region to the groin. The patient was morbidly obese, had renal dysfunction, and had diabetes mellitus diagnosed on admission.; her LRINEC (Laboratory Risk Indicator for Necrotising Fasciitis) score was 9, indicating a high risk of NF. An exploratory surgical incision was made, and NF was diagnosed based on fascial necrosis. Emergent surgical debridement was performed, and cultures of the tissue culture and aspirated fluid/pus revealed two types of Lactobacillus spp.: Lactobacillus salivarius and L. iners. The patient was admitted to the intensive care unit (ICU), where antibiotics were administered and respiratory and circulatory management was performed. Diabetic ketoacidosis was detected, which was treated by controlling the blood glucose level stringently via intravenous insulin infusion. The patient underwent a second debridement on day 11 and a skin suture and skin grafting on day 36. The patient progressed well, was transferred from the ICU to the general ward on day 41, and was discharged unassisted on day 73. CONCLUSIONS: Lactobacillus spp. are rarely pathogenic to healthy individuals and can scarcely trigger NF. However, these bacteria can cause rare infections such as NF in immunocompromised individuals, such as those with diabetes and obesity, and an early diagnosis of NF is imperative; surgical intervention may be required for the prevention of extensive necrosis. The LRINEC score may be useful for the early diagnosis of NF, even for less pathogenic bacteria such as Lactobacillus.

Cellular and transcriptomic response to pathogenic and non-pathogenic Vibrio parahaemolyticus strains causing acute hepatopancreatic necrosis disease (AHPND) in Litopenaeus vannamei.

The shrimp industry has historically been affected by viral and bacterial diseases. One of the most recent emerging diseases is Acute Hepatopancreatic Necrosis Disease (AHPND), which causes severe mortality. Despite its significance to sanitation and economics, little is known about the molecular response of shrimp to this disease. Here, we present the cellular and transcriptomic responses of Litopenaeus vannamei exposed to two Vibrio parahaemolyticus strains for 98 h, wherein one is non-pathogenic (VpN) and the other causes AHPND (VpP). Exposure to the VpN strain resulted in minor alterations in hepatopancreas morphology, including reductions in the size of R and B cells and detachments of small epithelial cells from 72 h onwards. On the other hand, exposure to the VpP strain is characterized by acute detachment of epithelial cells from the hepatopancreatic tubules and infiltration of hemocytes in the inter-tubular spaces. At the end of exposure, RNA-Seq analysis revealed functional enrichment in biological processes, such as the toll3 receptor signaling pathway, apoptotic processes, and production of molecular mediators involved in the inflammatory response of shrimp exposed to VpN treatment. The biological processes identified in the VpP treatment include superoxide anion metabolism, innate immune response, antimicrobial humoral response, and toll3 receptor signaling pathway. Furthermore, KEGG enrichment analysis revealed metabolic pathways associated with survival, cell adhesion, and reactive oxygen species, among others, for shrimp exposed to VpP. Our study proves the differential immune responses to two strains of V. parahaemolyticus, one pathogenic and the other nonpathogenic, enlarges our knowledge on the evolution of AHPND in L. vannamei, and uncovers unique perspectives on establishing genomic resources that may function as a groundwork for detecting probable molecular markers linked to the immune system in shrimp.

Tail Fan Necrosis syndrome in decapod crustaceans: A review.

Lobsters and crayfish in Australasia can develop a condition known as Tail Fan Necrosis (TFN syndrome). Many attempts have been made to find a primary pathogen or link the syndrome to commercial activities, but a solution remains elusive. TFN syndrome is a 'wicked problem', a problem difficult or impossible to solve because of incomplete and contradictory information forming a matrix of potential outcomes with no simple solution. Reviewing the literature shows TFN syndrome is sometimes reported to develop in association with sterile blisters on the telson and uropods which may rupture permitting invasion by environmental fungal and/or bacterial flora. Whether blisters form prior to, or because of, infection is unknown. TFN syndrome sometimes develops in captivity, sometimes requires a previous insult to the telson and uropods, and prevalence is patchy in the wild. The literature shows the cause of blisters associated with TFN syndrome remains an enigma, for which we suggest several possible initiating factors. We strongly urge that researchers not 'jump to conclusions' as to the aetiology of TFN syndrome. It cannot be explained without carefully exploring alternative aetiologies whilst being cognisant of the age-old lesson that 'correlation does not equal causation'.

Role of autophagy machinery dysregulation in bacterial chondronecrosis with osteomyelitis.

Autophagy is a cell survival and homeostasis mechanism involving lysosomal degradation of cellular components and foreign bodies. It plays a role in bone homeostasis, skeletal diseases, and bacterial infections as both a cell-survival or cell-death pathway. This study sought to determine if autophagy played a role in bacterial chondronecrosis with osteomyelitis (BCO). BCO is a prominent cause of lameness in modern broilers and results from bacterial infection of mechanically stressed leg bone growth plates. The protein and gene expression of key autophagy machinery was analyzed in both normal and BCO-affected broilers using real-time qPCR and immunoblot, respectively. Gene expression showed a significant downregulation of key target signatures involved in every stage of autophagy in BCO-affected bone, such as ATG13, SQSTM1 (p62), ATG9B, ATG16L, ATG12, LC3C, and RAB7A. Additionally, protein expression for LC3 was also significantly lower in BCO. An in vitro study using human fetal osteoblast cells challenged with BCO isolate, Staphylococcus agnetis 908, showed a similar dysregulation of autophagy machinery along with a significant decrease in cell viability. When autophagy was inhibited via 3-methyladenine or chloroquine, comparable decreases in cell viability were seen along with dysregulation of autophagy machinery. Together, these results are the first to implicate autophagy machinery dysregulation in the pathology of BCO.

Partial reproduction of ear-tip necrosis suggests an infectious, initially bacterial aetiology.

Swine ear-tip necrosis (ETN) is a disease of global presence and unclear aetiology. Little evidence is available regarding the nature of this disease. The aim of this work was to investigate if ETN is an infectious disease that could be replicated using a lesion macerate inoculum. A source farm with a history of ear-tip necrosis was identified and five weeks-old pigs (n = 12) from this farm were housed under controlled conditions and intradermally inoculated with ETN lesion macerates (right ear, n = 10) or sterile inoculum (left ear, n = 10). Two pigs were not inoculated, serving as sentinels. All animals were clinically monitored daily during 21 days, and a ETN ear score was used to follow disease progression. Anaerobic (n = 2) and aerobic (n = 2) overnight cultures, as well as raw aliquots of the lesion macerate inoculum (n = 2) and control inoculum (n = 2) were submitted for metagenomic sequencing. All inoculated ears developed lesions suggestive of early ETN, but none progressed to result in loss of the ear pinna. All completely resolved 21 days post-inoculation. Post-mortem investigation revealed areas of fibrosis, characterized by a granulomatous response in the inoculated ears (5/10) and in 1/10 control ears. Metagenomic analysis identified the presence of previously suggested bacterial etiological agents, but no relevant viral, fungal or protozoan agents in the inoculum. ETN etiology remains unclear, but an infectious cause and bacterial agents are suggested to be at least partially implicated in disease pathogenesis. Virus and fungi do not seem to significantly contribute to disease.

Bacteriophage mediated control of necrotic enteritis caused by C. perfringens in broiler chickens.

In Egypt, little attention has been paid to the isolation and application of C. perfringens phages for treating necrotic enteritis at the farm level. This study aims to evaluate the efficiency of the podovirus C. perfringens phage in treating necrotic enteritis in broiler chickens. Accordingly, C. perfringens phage was isolated from cecal samples of apparently healthy chickens and characterized by transmission electron microscopy, thermal stability test, and pH stability test. Commercial 14-day-old Arbor Acres broiler chickens were allocated to three groups: group Ӏ received BHI broth and assigned as a negative control, group П served as a positive control group that was challenged with C. perfringens via oral gavage for four successive days, and group Ш was administrated six phage doses on several occasions after oral gavage challenge with C. perfringens. Daily clinical symptoms and mortality were recorded. At three-time intervals, necrotic enteritis lesions were scored. Cecal samples were examined for re-isolation and counting of C. perfringens. The isolated C. perfringens phage was a podovirus with an icosahedral head diameter of 78.7 nm and a short non-contractile tail length of 22.2 nm. It remained stable for 60 min at 30 °C and 50 °C at pH values of 2, 4, 8, and 10. The phage-treated group (Ш) showed mild gross lesions with a lower mortality rate and reduced colony-forming units than the positive control group (П). The findings revealed that the isolated C. perfringens phage effectively treated experimental necrotic enteritis in broiler chickens.

The Effect of Different Species of Eimeria with Clostridium perfringens on Performance Parameters and Induction of Clinical Necrotic Enteritis in Broiler Chickens.

Necrotic enteritis (NE) is a common disease that causes great economic loss to the broiler industry due to mortality and reduced performance. Although Clostridium perfringens (CP) is a necessary component of this disease, coccidia species are a well-defined predisposing factor that exacerbates the condition. Different Eimeria species have been reported to influence NE to different degrees. In a pair of experiments, six different Eimeria species were evaluated in the presence and absence of C. perfringens. Male broiler chicks were housed in battery cages for the duration of both experiments. Feed conversion, body weight gain, and NE mortality were reported in both experiments. Experiment 1 challenged birds with E. maxima, E. acervulina, E. tenella, E. necatrix, and E. brunetti at day 13 and subsequently inoculated birds with CP on days 18, 19, and 20. In the second experiment, E. maxima, E. acervulina, E. tenella, and E. praecox were inoculated on day 15 and challenged with CP on days 17, 18, 19, 20, 21, and 22 of the experiment. In the first experiment, E. acervulina, E. brunetti, E. maxima, and E. necatrix with the addition of CP all stimulated necrotic enteritis mortality. In the second experiment, E. praecox had minimal impact on performance during the challenge (14-23 days) while E. maxima + CP decreased body weight gain and increased mortality compared to the CP alone control. Eimeria maxima had the highest mortality (21.9%) in this experiment followed by E. acervulina (6.3%). The remaining Eimeria with added CP in the second experiment did not induce NE mortality. While the challenge with CP alone did not induce mortality, feed conversion was increased compared to the unchallenged control group. When using isolated Eimeria species in these experiments, disturbances created by E. brunetti and E. maxima resulted in the most-severe challenges. These experiments highlight the NE risk of these species of Eimeria and give insight into how other species interact with the host in a controlled CP challenge model.

Artículo regular­Efecto de diferentes especies de Eimeria con Clostridium perfringens sobre los parámetros de rendimiento y la inducción de enteritis necrótica clínica en pollos de engorde. La enteritis necrótica (NE) es una enfermedad común que causa grandes pérdidas económicas a la industria del pollo de engorde debido a la mortalidad y a la reducción del rendimiento. Aunque Clostridium perfringens (CP) es un componente necesario de esta enfermedad, las especies de coccidia son un factor predisponente bien definido que agrava la enfermedad. Se ha informado que diferentes especies de Eimeria influyen en la enteritis necrótica en diferentes grados. En un par de experimentos, se evaluaron seis especies diferentes de Eimeria en presencia y ausencia de C. perfringens. Pollos de engorde machos se alojaron en jaulas en batería durante la duración de ambos experimentos. En ambos experimentos se analizaron la conversión alimenticia, el aumento de peso corporal y la mortalidad por enteritis necrótica. En el Experimento 1 se desafió a las aves con E. maxima, E. acervulina, E. tenella, E. necatrix y E. brunetti en el día 13 y posteriormente se inoculó a las aves con C. perfringens en los días 18, 19 y 20. En el segundo experimento, E. maxima, E. acervulina, E. tenella y E. praecox se inocularon en el día 15 y se desafiaron con C. perfringens en los días 17, 18, 19, 20, 21 y 22 del experimento. En el primer experimento, E. acervulina, E. brunetti, E. maxima y E. necatrix junto con C. perfringens estimularon la mortalidad por enteritis necrótica. En el segundo experimento, E. praecox tuvo un impacto mínimo en el rendimiento durante el desafío (14 a 23 días) mientras que el tratamiento de E. maxima + C. perfringens disminuyó el aumento de peso corporal y aumentó la mortalidad en comparación con el control con solamente C. perfringens. Eimeria maxima tuvo la mayor mortalidad (21.9%) en este experimento seguida por E. acervulina (6.3%). El resto de las especies de Eimeria junto con C. perfringens en el segundo experimento no indujeron mortalidad por enteritis necrótica. Si bien el desafío con C. perfringens no solo no indujo mortalidad, sino que la conversión alimenticia aumentó en comparación con el grupo de control no desafiado. Cuando se utilizaron especies de Eimeria aisladas en estos experimentos, los problemas creados por E. brunetti y E. maxima resultaron en los desafíos más severos. Estos experimentos destacan el riesgo por enteritis necrótica con estas especies de Eimeria y dan una idea de cómo otras especies interactúan con el hospedador en un modelo de desafío con C. perfringens controlado.

Global patterns of necrotizing soft tissue infections: A systematic review and meta-analysis.

BACKGROUND: Frequency, microbiology, and outcomes of necrotizing soft tissue infections vary based on locoregional and environmental factors; however, there has been no global survey of these patterns. We performed a systematic review/meta-analysis on published reports of necrotizing soft tissue infections from across the globe. METHODS: Peer-reviewed empirical studies examining rates of polymicrobial and monomicrobial necrotizing soft tissue infections with microbial isolation and overall mortality rate were extracted along with geographic location using PubMed, Scopus, ProQuest, and Web of Science. Random-effects meta-analyses and sensitivity analyses were performed, adjusting for publication bias. Meta-regression analyses examined moderator effects of risk factors. RESULTS: One hundred and five studies (8,718 total patients) were included. Pooled prevalence of polymicrobial and monomicrobial infections were 53% and 37.9%, respectively. Truncal necrotizing soft tissue infections were commonly polymicrobial (P < .001), whereas monomicrobial infections prevailed in extremities (P = .008). Global prevalence of monomicrobial necrotizing soft tissue infections was observed to increase by 1.1% annually (P = .003). Staphylococcus aureus was the most common organism globally and in North America, Asia, the Middle East, and Africa, followed by Streptococcus pyogenes and Escherichia coli. Methicillin-resistant S. aureus accounted for 16% of necrotizing soft tissue infections globally. Overall mortality was 23.1%, observed to decline globally over the last decade (P = .020). No regional differences were noted for mortality. CONCLUSION: Although polymicrobial infections remain predominant worldwide, the incidence of monomicrobial infections is increasing. The observed decline in necrotizing soft tissue infection-related mortality is encouraging and may reflect advances in management, despite major variations in available healthcare resources globally.

The Effect of Photoperiod on Necrosis Development, Photosynthetic Efficiency and 'Green Islands' Formation in Brassica juncea Infected with Alternaria brassicicola.

The main goal of growing plants under various photoperiods is to optimize photosynthesis for using the effect of day length that often acts on plants in combination with biotic and/or abiotic stresses. In this study, Brassica juncea plants were grown under four different day-length regimes, namely., 8 h day/16 h night, 12 h day/12 h night, 16 h day/8 h night, and continuous light, and were infected with a necrotrophic fungus Alternaria brassicicola. The development of necroses on B. juncea leaves was strongly influenced by leaf position and day length. The largest necroses were formed on plants grown under a 16 h day/8 h night photoperiod at 72 h post-inoculation (hpi). The implemented day-length regimes had a great impact on leaf morphology in response to A. brassicicola infection. They also influenced the chlorophyll and carotenoid contents and photosynthesis efficiency. Both the 1st (the oldest) and 3rd infected leaves showed significantly higher minimal fluorescence (F0) compared to the control leaves. Significantly lower values of other investigated chlorophyll a fluorescence parameters, e.g., maximum quantum yield of photosystem II (Fv/Fm) and non-photochemical quenching (NPQ), were observed in both infected leaves compared to the control, especially at 72 hpi. The oldest infected leaf, of approximately 30% of the B. juncea plants, grown under long-day and continuous light conditions showed a 'green island' phenotype in the form of a green ring surrounding an area of necrosis at 48 hpi. This phenomenon was also reflected in changes in the chloroplast's ultrastructure and accelerated senescence (yellowing) in the form of expanding chlorosis. Further research should investigate the mechanism and physiological aspects of 'green islands' formation in this pathosystem.

The microbial profile of a tissue necrosis affecting the Atlantic invasive coral Tubastraea tagusensis.

The Southwestern Atlantic rocky reef ecosystems are undergoing significant changes due to sun-corals (Tubastraea tagusensis and T. coccinea) invasion. At Búzios Island, on the northern coast of São Paulo State, where the abundance of T. tagusensis is particularly high, some colonies are displaying tissue necrosis, a phenomenon never reported for this invasive nor any other azooxanthellate coral species. Using next-generation sequencing, we sought to understand the relationship between T. tagusensis tissue necrosis and its microbiota. Thus, through amplicon sequencing, we studied both healthy and diseased coral colonies. Results indicate a wide variety of bacteria associated with healthy colonies and an even higher diversity associated with those corals presenting tissue necrosis, which displayed nearly 25% more microorganisms. Also, as the microbial community associated with the seven healthy colonies did not alter composition significantly, it was possible to verify the microbial succession during different stages of tissue necrosis (i.e., initial, intermediate, and advanced). Comparing the microbiome from healthy corals to those in early tissue necrosis suggests 21 potential pathogens, which might act as the promoters of such disease.

Porcine ear necrosis.

Porcine ear necrosis (PEN) is a condition that mainly occurs in intensive pig production systems and mostly affects piglets after weaning. The syndrome manifests itself with lesions on the pinna, which can heal or become more severe resulting in partial loss of the ear. The pathogenesis of the condition is not fully known. Three different hypotheses for the development of PEN are described in this review: (1) damage of the epidermis due to Staphylococcal exfoliative toxins; (2) occlusion of small blood vessels; and (3) ear biting with subsequent ß-hemolytic streptococcal infection. Risk factors have not been completely elucidated, but viral and bacterial infections, and husbandry factors such as environment, housing conditions and management, have been suggested. It is also possible that some cases are due to a combination of these factors. The role of parasitic infestations has been not investigated. Due to bacterial involvement, severely affected pigs can be treated with antimicrobials. Control and preventive measures should focus on reducing potential risk factors by implementing herd immunization, as well as improvement of sanitary conditions, feed quality (with respect to mycotoxin contamination), management (appropriate stocking density), and environmental conditions (e.g. number of drinkers and feeders and/or optimal ventilation). Further research is needed to better understand the precise etiology and pathogenesis of PEN, so that risk factors can be identified and more targeted control measures can be implemented.

A study of the microbiological profile of filler-induced skin necrosis.

Skin necrosis is one of the most severe complications following filler injections, and can result in permanent aesthetic defects. Although an increasing number of studies have addressed the management of dermal filler complications, no study has described the spectrum of microbial pathogens. The aim of this study was to delineate the bacterial profile and prognostic factors of filler-related skin necrosis by reviewing the clinical and microbiological features of these patients. A retrospective medical record review of patients undergoing treatment for skin necrosis induced by fillers was conducted. In total, 10 cases were identified, with injection sites being the nasolabial fold (70%; n = 7), nasal dorsum (20%; n = 2) and nasal tip (10%; n = 1). Reviewing the culture results, the true culture-positive rate was found to be 50% after cases of contamination were excluded. To avoid permanent sequelae, all physicians should be aware of possible secondary infections when treating filler-induced skin necrosis.

Crayfish (Cherax quadricarinatus) susceptibility to acute hepatopancreatic necrosis disease (AHPND).

Acute hepatopancreatic necrosis disease (AHPND) is an OIE-listed enteric disease that has continued to plague the shrimp aquaculture industry since its first discovery in 2009. AHPND is one of the biggest disease threats to the shrimp aquaculture industry along with white spot disease (WSD) which has severely impacted both crayfish and shrimp aquaculture. AHPND is caused by specific marine Vibrio spp. which carry plasmid-borne binary toxins PirAVp and PirBVp. This research investigated if crayfish are susceptible to AHPND-causing Vibrio parahaemolyticus (VpAHPND) to discern the potential risk that AHPND may pose to the crayfish aquaculture industry. Susceptibility was investigated by challenging Cherax quadricarinatus (Australian red claw crayfish) and Penaeus vannamei (Pacific white shrimp) with VpAHPND in a cohabitation immersion bioassay. Upon termination of the bioassay, crayfish survival was significantly higher than shrimp survival (87% vs. 33%). Hepatopancreas dissected from experimentally challenged animals were screened for the binary toxin genes pirAVp and pirBVp by real-time and duplex conventional PCR assays, and also were examined by H&E histology for the detection of characteristic AHPND pathology. Although AHPND toxin genes pirAVp and pirBVp were detected in a subset of crayfish samples, histopathology did not reveal any pathognomonic lesions that are characteristic of AHPND in any crayfish samples examined. These findings suggest that crayfish are likely resistant to AHPND.

Research Note: The administration schedule of coccidia is a major determinant in broiler necrotic enteritis models.

A reliable and reproducible in vivo experimental model is an essential tool to study the pathogenesis of broiler necrotic enteritis and to evaluate control methods. Most current in vivo models use Eimeria as predisposing factor. Nevertheless, most models only result in a limited number of animals with intestinal necrosis. This research describes the necrotic enteritis incidence and severity using 2 previously described experimental models varying in the time point and frequency of Eimeria administration: single late and early repeated Eimeria administration models. In an in vivo model in which Clostridium perfringens is administered at 3 consecutive days between day 18 and 20 of age, birds belonging to the single late Eimeria administration regimen received a single administration of a tenfold dose of a live attenuated Eimeria vaccine on the second day of C. perfringens challenge. Broilers belonging to the early repeated administration regimen were inoculated with the same Eimeria vaccine 4 and 2 d before the start of the C. perfringens challenge. Early repeated coccidial administration resulted in a significant increase in average necrotic lesion score (value 3.26) as compared with a single late Eimeria administration regimen (value 1.2). In addition, the number of necrotic enteritis-positive animals was significantly higher in the group that received the early repeated coccidial administration. Single Eimeria administration during C. perfringens challenge resulted in a skewed distribution of lesion scoring with hardly any birds in the high score categories. A more centered distribution was obtained with the early repeated Eimeria administration regimen, having observations in every lesion score category. These findings allow better standardization of a subclinical necrotic enteritis model and reduction of the required numbers of experimental animals.

Antibody-Mediated Protection against Staphylococcus aureus Dermonecrosis: Synergy of Toxin Neutralization and Neutrophil Recruitment.

The staphylococcal α-hemolysin is critical for the pathogenesis of Staphylococcus aureus skin and soft tissue infection. Vaccine and infection-elicited α-hemolysin-specific antibodies protect against S. aureus‒induced dermonecrosis, a key feature of skin and soft tissue infection. Many interactions between α-hemolysin and host cells have been identified that promote tissue damage and modulate immune responses, but the mechanisms by which protective adaptive responses cross talk with innate responses at the tissue level are not clear. Using an established mouse model of skin and soft tissue infection and a newly developed histopathologic scoring system, we observed pathologic correlates early after infection, predicting protection against dermonecrosis by anti-α-hemolysin antibody. Protection was characterized by robust neutrophilic inflammation and compartmentalization of bacteria into discrete abscesses, which led to the attenuation of dermonecrosis and enhancement of bacterial clearance later in the infection. The ultimate outcome of infection was driven by the recruitment of neutrophils within the first day after infection but not later. Antibody-mediated protection was dependent on toxin neutralization rather than on enhanced opsonophagocytic killing by neutrophils or protection against toxin-mediated neutrophil lysis. Together, these findings advance our understanding of the mechanisms by which the early synergism between antibody-mediated toxin neutralization and tissue-specific neutrophilic inflammation preserve tissue integrity during infection.

Staphylococcus aureus Descending Necrotizing Mediastinitis in a Healthy Adult.

Descending necrotizing mediastinitis (DNM) is a severe form of mediastinitis with high mortality rates due to the rapid progression of infection into the mediastinum through tissue planes, often from a dental or pharyngeal source. We present a case of monomicrobial methicillin-resistant Staphylococcus aureus DNM in a healthy young man who was initially misdiagnosed with strep throat. This is well described in the pediatric literature; however, DNM in adults is typically polymicrobial and occurs in those with comorbidities such as diabetes mellitus and older age. Survival is excellent with early identification of mediastinitis, prompt surgical intervention, and appropriate antibiotics.

Antigenicity of hypothetical protein HP33 of Vibrio harveyi Y6 causing scale drop and muscle necrosis disease in Asian sea bass.

A unique strain of Vibrio harveyi is the causative agent of scale drop and muscle necrosis disease (SDMND) in Asian sea bass (Lates calcarifer). This study investigated the protein profiles of SDMND-causing Vibrio harveyi isolates compared to the reference V. harveyi ATCC 14126 strain. A distinct protein band of 33 kDa, namely HP33, found from only V. harveyi SDMND was subjected to analysis by LC-MS/MS and the identified peptide sequences matched to an unknown hypothetical protein. Detection of HP33 coding sequence was investigated at both genomic and transcriptional levels and the results consistently supported the protein analysis. Recombinant HP33 protein was then produced using Escherichia coli system. The rHP33 protein did not cause mortality or visible clinical signs to Asian sea bass. However, the rHP33 protein was able to stimulate antibody response in Asian sea bass as evidenced by Western blotting and agglutination tests. Here, we proposed that rHP33 might be a good protein target for development of subunit vaccine and/or immunostimulant to protect Asian sea bass from SDMND.