The application of an alanine-substituted mutant of the C-terminal fragment of Clostridium perfringens enterotoxin as a mucosal vaccine in mice

Efficient delivery of antigen to mucosal immune tissues is an essential part of mucosal vaccination. Claudin-4 is expressed on the epithelial cells that cover the mucosal immune tissues. We previously found that claudin-4-targeting is a promising strategy for mucosal vaccination by using a claudin-4 binder, the C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE). Substitution of Asn and Ser at positions 309 and 313, respectively, with alanine increased the affinity of C-CPE for claudin-4. However, application of the C-CPE mutant as a mucosal vaccine has never been tried. Here, we investigated whether the C-CPE mutant could serve as a mucosal vaccine. We used ovalbumin (OVA) as a model antigen and fused the C-CPE mutant to it. The resultant fusion protein was bound to claudin-4. When mice were immunized with the C-CPE mutant-fused OVA, OVA-specific serum IgG and nasal IgA increased relative to levels in mice immunized with a C-CPE-fused antigen. Immunization with the C-CPE mutant-fused OVA activated Th1- and Th2-type responses and led to increased anti-tumor activity against OVA-expressing thymoma cells relative to that of mice immunized with the C-CPE-fused antigen. These findings suggest that the alanine-substituted C-CPE mutant shows promise as a claudin-targeted mucosal vaccine.     

A double antibody sandwich enzyme-immunoassay for Clostridium perfringens type A enterotoxin detection in stool specimens

A double antibody sandwich enzyme-immunoassay has been developed for detection of Clostridium perfringens enterotoxin. Anti-enterotoxin immunoglobulin G-alkaline phosphatase conjugates were prepared using a rapid minicolumn procedure. The assay can achieve a sensitivity of greater than or equal to 1 ng/ml with purified enterotoxin. Sensitivity for detection of cases of C. perfringens enteritis in a C. perfringens outbreak (86 individuals tested) was between 85.7 and 98.0 per cent depending upon stringency of criteria for defining positive cases. Specificity of the assay was demonstrated by the lack of positive results in 53 individuals involved in a gastroenteritis outbreak of unknown etiology.     

PCR identification of the plasmid-borne enterotoxin gene (cpe) in Clostridium perfringens strains isolated from food poisoning outbreaks

It is generally accepted that Clostridium perfringens strains associated with food poisoning carry their enterotoxin gene, cpe, on the chromosome, while C. perfringens strains isolated from non-food-borne diseases, such as antibiotic-associated diarrhea and sporadic diarrhea, carry cpe on the plasmid. However, we recently encountered a food poisoning outbreak caused by C. perfringens bearing a plasmid cpe. We therefore investigated a total of 31 clinical and non-clinical C. perfringens strains to locate the cpe gene by PCR. The cpe of nine heat-sensitive (100 degrees C for 10min) strains isolated from three outbreaks of food poisoning were located on the plasmid, while those of six heat-resistant strains from other food poisoning outbreaks were located on the chromosome. Moreover, the cpe of 5 heat-sensitive strains isolated from healthy human feces and those of 11 heat-sensitive soil strains were also located on the plasmid. These findings indicate that heat-sensitive, cpe-plasmid-borne C. perfringens strains should not be disregarded as causative agents of food poisoning.     

A chicken intestinal ligated loop model to study the virulence of Clostridium perfringens isolates recovered from antibiotic-free chicken flocks

Necrotic enteritis (NE) is a major problem in antibiotic-free (ABF) chicken flocks and specific strains of Clostridium perfringens are known to induce NE. The objective of this study was to develop a chicken intestinal ligated loop model in order to compare the virulence of various C. perfringens strains recovered from consecutive ABF flocks with and without NE. Intestinal loops were surgically prepared in 10 anaesthetized specific-pathogen-free chickens and alternately inoculated with C. perfringens isolates or brain heart infusion (BHI) media. Histological lesion scoring was performed for each loop. All strains from NE-affected flocks induced histological lesions compatible with NE whereas inoculation of loops with a commensal C. perfringens strain or BHI did not. Among inoculated strains, CP0994 (netB-positive and cpb2-positive) and CP-2003-1256 (netB-positive) demonstrated mean histological lesion scores significantly higher (P?netB-negative and cpb2-positive) induced intestinal lesions without significantly higher scores. In loops where villi were colonized by Gram-positive rods, significantly higher (P?C. perfringens is a critical step in the pathogenesis of NE. Finally, we demonstrated the importance of controlling virulent C. perfringens strains in ABF chicken flocks as a highly virulent strain can be present in consecutive flocks with NE and possibly affect multiple flocks.     

A hypothesis concerning Clostridium perfringens type A enterotoxin (CPE) and Sudden Infant Death Syndrome (SIDS)

This study identifies the presence of Clostridium perfringens type A enterotoxin (CPE) in some gastrointestinal and serum samples from babies who had died of the Sudden Infant Death Syndrome (SIDS) and other causes. On occasion antibodies to this toxin were identified in sera. CPE is parasympathomimetic in its action. In the adult food poisoning model it is produced when the organism sporulates in vivo. This leads to speculation as to whether this toxin may play an ante-mortem role in the dying process of infants, either in the agonal stages or as a causative factor in SIDS.     

European Society of Clinical Microbiology and Infectious Diseases (ESCMID): treatment guidance document for Clostridium difficile infection (CDI)

Clostridium difficile infection (CDI) is a potentially fatal illness with an increasing incidence worldwide. Despite extensive ongoing research into CDI treatment, management of CDI still poses important problems, such as a high propensity to relapse and refractoriness to treatment, especially when there is an ileus and oral drugs cannot be adminstered. This guideline evaluates the available literature, discusses criteria for disease severity and provides recommendations for CDI treatment, indicating level of evidence and strength of recommendation.     

European Society of Clinical Microbiology and Infectious Diseases (ESCMID): Data review and recommendations for diagnosing Clostridium difficile-infection (CDI)

The aim of the present systematic review was to evaluate the available evidence on laboratory diagnosis of CDI and to formulate recommendations to optimize CDI testing. In comparison with cell culture cytotoxicity assay (CCA) and toxigenic culture (TC) of stools, we analyzed the test characteristics of 13 commercial available enzyme immunoasssays (EIA) detecting toxins A and/or B, 4 EIAs detecting Clostridium difficile glutamate dehydrogenase (GDH), and a real-time PCR for C. difficile toxin B gene. In comparison with CCA and TCA and assuming a prevalence of CDI of 5%, PPV and NPV varied between 0.28–0.77, 0.12–0.65 and 0.98–1.00, 0.97–1.00, respectively. Only if the tests were performed in a population with a CDI prevalence of 50 percent, would PPVs be acceptable (ranging from 0.71 to 1.00).To overcome the problem of a low PPV, we propose a two step approach, with a second test or a reference method in case of a positive first test. Further reducing the number of false negative results would require either retesting of all subjects with a negative first test, or re-testing all subjects with a negative second test, after an initially positive test. This approach resulted in non-significant improvements, and emphasizes the need for better diagnostic tests. Further studies to validate the applicability of two-step testing, including assessment of clinical features, are required.     

A Human Vaccine Strain of Lamb Rotavirus (Chinese) NSP4 Gene: Complete Nucleotide Sequence and Phylogenetic Analyses

A lamb strain of rotavirus has recently been licensed for use in China as a live vaccine to prevent rotavirus diarrhea in children. As rotavirus NSP4, especially the cytotoxic domain alone is considered to be associated with diarrhea, we sequenced gene segment 10, which encodes NSP4, of lamb rotavirus. Comparative analyses was performed to identify differences from human rotavirus strains, that might be associated with attenuation, and to ascertain whether the lamb rotavirus gene fits among the NSP4 of other sequenced rotavirus strains. Our comparative nucleotide sequence analysis suggests its close identity (91.17% homology) with that of group-A equine rotavirus (strain HI23). Multiple alignment of the deduced amino acid sequence of lamb NSP4 with that of other group A rotaviruses demonstrated homology ranging from 63.42% with that of porcine YM strain to 93.71% with equine HI23 strain of rotavirus. A group A-specific NSP4 monoclonal antibody recognized the glycosylated and unglycosylated forms of the protein from virus-infected lysates, suggesting a well-conserved group-specificity of the lamb NSP4. Phylogenetic analysis of the lamb rotavirus gene, with 60 other NSP4 gene sequences of human and animal rotavirus strains, demonstrated that the lamb rotavirus strain belongs to genotype A. Comparative analysis also revealed that although it is a vaccine strain, the NSP4 cytotoxic domain of lamb strain demonstrated an overall amino acid conservation similar to that of other strains, whose NSP4 alone causes diarrhea in animal models. These results taken together with our previous observations clearly reaffirm the idea that the attenuation phenotype of rotaviruses does not involve NSP4 cytotoxic domain, perhaps due to the suppression of NSP4 cytotoxic activity by other rotaviral proteins.     

Highly cross-linked polyethylene (HXLPE) is equivalent to conventional polyethylene (CPE) in total knee arthroplasty: A systematic review and meta-analysis

BackgroundThe benefits of HXLPE in total knee arthroplasty (TKA) have not been as evident as total hip arthroplasty (THA). A systematic review and meta-analysis to assess the impact of highly-crosslinked polyethylene (HXLPE) on TKA outcomes compared to conventional polyethylene (CPE) is described.MethodsAll studies comparing HXLPE with CPE for primary TKA were included for analysis. The minimum dataset included revision rates, indication for revision, aseptic component loosening and follow-up time. The primary outcome variables were all-cause revision, aseptic revision, revision for loosening, radiographic component loosening, osteolysis and incidence of radiolucent lines. Secondary outcome measures included postoperative functional knee scores. A random-effects meta-analysis allowing for all missing data was performed for all primary outcome variables.ResultsSix studies met the inclusion criteria. In total, there were 2,234 knees (1,105 HXLPE and 1,129 CPE). The combined mean follow-up for all studies was 6 years. The aseptic revision rate in the HXLPE group was 1.02% compared to 1.97% in the CPE group. There was no difference in the rate of all-cause revision (p = 0.131), aseptic revision (p = 0.298) or revision for component loosening (p = 0.206) between the two groups. Radiographic loosening (p = 0.200), radiolucent lines (p = 0.123) and osteolysis (p = 0.604) was similar between both groups. Functional outcomes were similar between groups.ConclusionThe use of HXLPE in TKA yields similar results for clinical and radiographic outcomes when compared to CPE at midterm follow-up. HXLPE does not confer the same advantages to TKA as seen in THA.     

Enteroaggregative Escherichia coli Heat-Stable Enterotoxin 1 (EAST1): A New Toxin with an Old Twist

Enteroaggregative Escherichia coli heat-stable enterotoxin 1 (EAST1) is a small protein that was first detected more than a decade ago in an enteroaggregative E. coli (EAEC) strain isolated from the stools of a diarrheic child. The EAST1 gene, astA, is not solely present in EAEC, but also in other categories of diarrheagenic E. coli. Strains expressing EAST1 have been shown to induce diarrhea principally in humans, although they have also been associated with piglets and calves. EAST1 toxin has been proposed as a virulence factor implicated in the mechanism of pathogenesis of EAEC and could play a role in the pathogenicity of other enteropathogens as well. This toxin is often compared to E. coli STa enterotoxin because they share some physical and mechanistic similarities. This review summarizes the various observations on EAST1 since its discovery.     

Frequent Isolations of Influenza A Viruses (H1N1)pdm09 with Identical Hemagglutinin Sequences for More Than Three Months in Japan

Background

Although it has been suggested that antigenic drift does not occur in a single epidemic season in temperate countries, there is not enough evidence on the circulation period of influenza virus with identical nucleotide sequences. Therefore, strains of influenza virus were isolated sequentially during five consecutive epidemic seasons in Japan and their nucleotide sequences were determined.

Methods

Nasal swabs or aspirated nasal discharges were collected from influenza A virus antigen-positive individuals living in Tottori Prefecture, Japan for five consecutive winters starting in 2009–2010, and subjected to viral isolation, determination of hemagglutinin nucleotide sequence and phylogenic analyses. The nucleotide sequences were compared with each other and also with those of foreign strains in the International Nucleotide Sequence Database.

Results

Totally 288 A(H1N1)pdm09 strains were tested and those composed 38 clusters with identical ones displaying 100% nucleotide homology. One strain showed sequential infections more than three months without any detectable mutation, and a maximum interval of two detection timings of strains was 94 days. This implies that influenza viruses mutate rarely in an epidemic season in Japan if they can be hypothesized, mutation frequency of influenza viruses being mostly the same among strains. Among these identical strains, two strains were not only identical to other Japanese isolates, but also to those isolated in Mongolia and Thailand in the same epidemic season.

Conclusion

These results suggest that genetic drift has occurred infrequently in Japan as shown in some other countries. The drifted strains may have generated somewhere else and entered into Japan. These results support the proposed ‘sink-source’ model of viral ecology in which new lineages are seeded from a persistent influenza reservoir in tropical countries to ‘sink’ populations in temperate regions including Japan.     

Battleground Zero: A Review of Best Practice Recommendations for Clostridioides (Clostridium) difficile Testing

Diagnosing Clostridioides (formerly Clostridium) difficile infection can be difficult, especially when there is a lack of consensus in the definition, disagreement on the gold standard, and indecision as to which is the best testing method. As laboratorians, we look to published best practice documents for guidance, but oftentimes, the recommendations are not straightforward. This article reviews the most recent guidance documents published by the Infectious Diseases Society of America/Society of Healthcare Epidemiology of America, the American College of Gastroenterology, the European Society of Clinical Microbiology and Infectious Diseases, and the American Society for Microbiology. Recommendations for the desired testing population, most accurate diagnostic test or testing algorithm, and frequency of testing are compared between the societies. A review of the guidance methodologies is provided, and strategies for laboratory adoption are discussed.     

Association of Nod‐like receptor protein‐1 (rs2670660) and Toll‐like receptor‐4 (rs4986790) with non‐segmental vitiligo: A case–control study in South Indian population

Non‐segmental vitiligo (NSV) is an autoimmune skin disease. Genetics plays a predominant part in disease pathogenesis. Nucleotide‐binding and oligomerization domain (NOD)‐like receptors and pyrin‐containing protein (NLRP) and Toll‐like receptors (TLR) are pattern recognition receptors in mediating innate immunity. They participate in presenting pathogens and mediating the immune responses. NLRP and TLRs are involved in mediating immune response in various dermatological diseases. Understanding the influence of genetic polymorphisms of NLRP and TLRs associated with immune homeostasis might help us to understand the complex etiopathogenesis of NSV. Thus, we aimed to study the association of NLRP‐1 (rs2670660) and TLR‐4 (rs4986790) and the synergistic effects on disease spectrum, disease activity of NSV in South Indian population. This research was designed as a case–control genetic study with 264 patients and 264 controls. Genotyping of NLRP‐1 (rs2670660) and TLR‐4 (rs4986790) was performed by Taqman 5’ allele discrimination assay and ARMS‐PCR. Plasma levels of proteins were measured by enzyme‐linked immunosorbent assay (ELISA). A statistically significant difference was observed with the frequency of homozygous GG genotype of NLRP‐1 (rs2670660) (17.8% in cases vs. 5.3% in controls) (p < 0.0001; OR‐3.73; 95% CI‐1.94–7.14). Allele G was significantly frequent in 38% of the cases than in controls with 30% (p = 0.004; OR‐1.46; 95% CI‐1.13–1.89). Plasma NLRP‐1 level was significantly higher in patients compared to controls (p < 0.05). Amongst cases, the plasma NLRP‐1 levels did not show any difference with respect to their genotypes (p > 0.05). In TLR‐4 (rs4986790), no significant difference in the frequency of genotypes and allele between cases and controls (p = 0.80) was observed; nevertheless, plasma TLR‐4 was analogous between cases and controls (p > 0.05). Influence of genotype on plasma TLR‐4 showed no significant difference in TLR‐4 levels between GG and ancestral genotype AA, whilst heterozygous AG genotype showed a significant increase of TLR‐4 compared to AA and GG (p = 0.02) amongst NSV cases. The obtained results suggest that NLRP‐1 (rs2670660), and not TLR‐4 ((rs4986790), is associated with increased risk of NSV in South Indian population.     

Avoid diagnostic delay of late infantile and juvenile neuronal ceroid-lipofuscinosis (LINCL,JNCL): A word to pediatricians,neurologists, and ophthalmologists

We describe a large family with congenital microtia, auditory meatal atresia and conductive deafness. The pedigree suggests autosomal dominant inheritance with variable expression and low penetrance. The literature is also reviewed to describe the inheritance pattern and clinical spectrum noted in this rare syndrome so far. The family is unique because the set of otologic anomalies in five generations was associated with renal cysts in one of the affected members, suggesting that this oto-renal (OR) syndrome may represent a variable expression of the branchio-oto-renal (BOR) syndrome. However, the probability is that this dominant malformation syndrome is a distinct entity. © 1995 Wiley-Liss, Inc.     

Mystacial Whisker Layout and Musculature in the Guinea Pig (Cavia porcellus): A Social,Diurnal Mammal

All mammals (apart from apes and humans) have whiskers that make use of a similar muscle arrangement. Whisker specialists, such as rats and mice, tend to be nocturnal and arboreal, relying on their whisker sense of touch to guide exploration around tree canopies at night. As such, nocturnal arboreal rodents have many whiskers that are organised into a grid‐like pattern, and moved using a complex array of muscles. Indeed, most arboreal, nocturnal mammals tend to have specialised whiskers that are longer and arranged in a dense, regular grid, compared with terrestrial, diurnal mammals. The guinea pig diverged early from murid rodents (around 75 million years ago), and are ground‐dwelling, diurnal animals. It would be predicted that, as a terrestrial mammal, they may have less whiskers and a reduced muscle architecture compared to arboreal, nocturnal rodents. We examined the mystacial whisker layout, musculature and movement capacity of Guinea pig (Cavia porcellus) whiskers and found that they did indeed have a disorganized whisker layout, with a fortification around the eye area. In addition, there was a reduction in musculature, especially in the intrinsic muscles. Despite guinea pigs not cyclically moving their whiskers, the mystacial musculature was still very similar to that of murid rodents. We suggest that the conserved presence of whisker layout and musculature, even in visual mammals such as primates and guinea pigs, may indicate that whiskers still play an important role in these animals, including protecting the eyes and being involved in tactile social behaviors. Anat Rec, 300:527–536, 2017. © 2016 Wiley Periodicals, Inc.     

Sodium channel gene (SCN5A) mutations in 44 index patients with Brugada syndrome: different incidences in familial and sporadic disease

The Brugada syndrome (BS) is a distinct form of idiopathic ventricular fibrillation and may cause sudden cardiac death in healthy young individuals. In the surface ECG, BS can be recognized by an atypical right bundle branch block and ST-segment elevation in the right precordial leads. Mutations in the cardiac sodium channel gene SCN5A are only known to cause BS. In a multi-center effort, we have collected clinical data on 44 unrelated index patients and family members and performed a complete genetic analysis of SCN5A. In 37% the disease was familial, whereas in the majority it was sporadic (63%). Five novel SCN5A mutations (2602delC, resulting in: E867X; 2581_2582del TT: F861fs951X; 2673G>A: E1225K; 4435_4437delAAG: K1479del; and 5425C>A: S1812X) were found and were randomly located in SCN5A. Mutation frequencies (SCN5A+) differed significantly between familial (38%) and sporadic disease (0%) (p=0.001). Disease penetrance was complete in the SCN5A+ adult patients, but incomplete in SCN5A+ children (17%). Genetic testing of SCN5A is especially useful in familial disease to identify individuals at cardiac risk. In sporadic cases, however, a genetic basis and the value of mutation screening has to be further determined. These results are in line with a possibly genetic and clinical heterogeneity of BS.     

Cyclic AMP‐dependent protein kinase catalytic subunit A (PRKACA): the expected,the unexpected,and what might be next

Protein kinase A (PKA) or cyclic‐AMP (cAMP)‐dependent kinase was among the first serine–threonine kinases to be molecularly and functionally characterized. For years, it was investigated as the enzyme that mediates cAMP functions in almost all cell systems and organisms studied to date. Despite PKA's critical role in signaling and the long history of investigations of cAMP in oncogenesis (dating back to the 1970s), it was not until relatively recently that PKA defects were found to be directly involved in tumor predisposition. First, PKA's main regulatory subunit, PRKAR1A, was found to be mutated in Carney complex, a genetic syndrome that predisposes to heart tumors (cardiac myxomas) and a variety of other lesions of the endocrine system, including the adrenal cortex, and several cancers, including liver carcinoma. Then, PKA's main catalytic subunit, PRKACA, was found to be mutated in sporadic adrenal tumors and fibrolamellar liver carcinoma. Not surprisingly, therefore, a new research study published in The Journal of Pathology showed PRKACA mutations in sporadic cardiac myxomas. The real question is what other pathologies will be found to be due to PRKACA (or other PKA subunit) defects. The possibilities abound and may show the way for a totally new class of medications that target cAMP signaling to be useful in fighting the corresponding tumors. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.     

Efficacy and Safety of Crofelemer for Noninfectious Diarrhea in HIV-Seropositive Individuals (ADVENT Trial): A Randomized,Double-Blind,Placebo-Controlled,Two-Stage Study

Abstract

Background: HIV-associated diarrhea remains a significant concern with limited treatment options. Objective: To determine the optimal dose, efficacy, and safety of crofelemer for noninfectious diarrhea. Methods: This randomized, double-blind, phase 3 trial used a 2-stage design. Both stages included 2-week screening, 4-week placebo-controlled treatment, and 20-week placebo-free (open-label) extension phases. In stage I, 196 HIV-seropositive patients with chronic diarrhea were randomized to crofelemer 125 mg, 250 mg, or 500 mg or placebo twice daily. Using a prospective analysis, the 125-mg twice-daily dose was selected for stage II. In stage II, 180 new patients were randomized to crofelemer 125 mg twice daily or placebo for 4 weeks. Primary efficacy analysis was the percentage of patients (stages I/II combined) who achieved clinical response (defined as ≤2 watery stools/week during ≥2 of 4 weeks). During the placebo-free extension phase, response (≤2 watery stools) was assessed weekly. Results: Significantly more patients receiving crofelemer 125 mg achieved clinical response versus placebo (17.6% vs 8.0%; one-sided, P = .01). Crofelemer 125 mg resulted in a greater change from baseline in number of daily watery bowel movements (P = .04) and daily stool consistency score (P = .02) versus placebo. During the placebo-free extension phase, percentages of weekly responders ranged from 40% to 56% at weeks 11 to 24. Crofelemer was minimally absorbed, well tolerated, did not negatively impact clinical immune parameters, and had a safety profile comparable to placebo. Conclusions: In HIV-seropositive patients taking stable antiretroviral therapy, crofelemer provided significant improvement in diarrhea with a favorable safety profile.