Improving gut function in pigs to prevent dysbiosis and post-weaning diarrhoea

Post-weaning diarrhoea (PWD) is a significant enteric disease causing considerable economic losses for the pig industry. There are multiple factors for why pigs develop diarrhea post-weaning and require treatment with antibiotics. The condition ‘dysbiosis’ can be considered as an ecosystem where bacteria no longer live together in mutual harmony. With regard to development of PWD, we therefore consider this as a process in a simplistic manner, i.e., dysbiosis appears when the commensal no longer control the potential pathogenic bacteria. When the pathogenic bacteria colonize and adhere to the epithelium of the gut, they may induce diarrhea. There are a number of factors by which the gut function can be improved, and prevention of dysbiosis exert a major role herein. The objective is to provide an overview of factors, which may enhance gut function both in terms of a balanced or eubiotic ecosystem, and with regard to the epithelial barrier function.

NanI Sialidase Enhances the Action of Clostridium perfringens Enterotoxin in the Presence of Mucus

NanI is a sialidase produced by some Clostridium perfringens type F strains. Here, we found that NanI can significantly increase the action of C. perfringens enterotoxin (CPE), which is the main toxin responsible for severe human enteric disease caused by type F strains. This effect likely helps to explain why even some type F strains that produce small amounts of CPE are pathogenic.

A site assessment tool for inpatient controlled human infection models for enteric disease pathogens

The use of the controlled human infection model to facilitate product development and to advance understanding of host-pathogen interactions is of increasing interest. While administering a virulent (or infective) organism to a susceptible host necessitates an ongoing evaluation of safety and ethical considerations, a central theme in conducting these studies in a safe and ethical manner that yields actionable data is their conduct in facilities well-suited to address their unique attributes. To that end, we have developed a framework for evaluating potential sites in which to conduct inpatient enteric controlled human infection model to ensure consistency and increase the likelihood of success.

Identification of a canine coronavirus in Australian racing Greyhounds

Coronavirus infection can cause a range of syndromes, which in dogs can include mild-to-severe enteritis that generally resolves rapidly. Fatalities can occur from coinfection with other pathogens, including canine parvovirus. Between late December 2019 and April 2020, canine coronavirus (CCoV) was detected in Australian racing Greyhounds that displayed signs of gastrointestinal disease. The CCoV was genotyped using high-throughput sequencing, recovering 98.3% of a type IIb CCoV, generally thought to cause a mild but highly contagious enteric disease. The Australian CCoV was almost identical (99.9%, whole-genome sequence) to another CCoV associated with an outbreak of severe vomiting in dogs in the United Kingdom at the same time (December 2019–March 2020).

Identification of a novel statovirus in a faecal sample from a calf with enteric disease

A novel clade of RNA viruses was identified in the mammalian gastrointestinal tract by next-generation sequencing. Phylogenetically, these viruses are related to the genera Tombusviridae (plant viruses) and Flaviviridae, which includes mammalian, avian and insect hosts. Named in line with their characterization as stool-associated Tombus-like viruses, it is unclear if statoviruses infect mammals or are dietary in origin. Here, metagenomic sequencing of faecal material collected from a 10-week-old calf with enteric disease found that 20 % of the reads mapped to a de novo-assembled 4 kb contig with homology to statoviruses. Phylogenetic analysis of the statovirus genome found a clear evolutionary relationship with statovirus A, but, with only 47 % similarity, we propose that the statovirus sequence presents a novel species, statovirus F. A TaqMan PCR targeting statovirus F performed on faecal material found a cycle threshold of 11, suggesting a high titre of virus shed from the calf with enteric disease. A collection of 48 samples from bovine enteric disease diagnostic submissions were assayed by PCR to investigate statovirus F prevalence and 6 of 48 (12.5 %) were positive. An ELISA to detect antibodies to the coat protein found that antibodies to statovirus F were almost ubiquitous in bovine serum. Combined, the PCR and ELISA results suggest that statovirus F commonly infects cattle. Further research is needed to elucidate the aetiological significance of statovirus infection.

Genome-wide analysis provides a deeper understanding of the population structure of the Salmonella enterica serotype Paratyphi B complex in Bangladesh

The Salmonella enterica serotype Paratyphi B complex causes a wide range of diseases, from gastroenteritis to paratyphoid fever, depending on the biotypes Java and sensu stricto. The burden of Paratyphi B biotypes in Bangladesh is still unknown, as these are indistinguishable by Salmonella serotyping. Here, we conducted the first whole-genome sequencing (WGS) study on 79 Salmonella isolates serotyped as Paratyphi B that were collected from 10 nationwide enteric disease surveillance sites in Bangladesh. Placing these in a global genetic context revealed that these are biotype Java, and the addition of these genomes expanded the previously described PG4 clade containing Bangladeshi and UK isolates. Importantly, antimicrobial resistance (AMR) genes were scarce amongst Bangladeshi S. Java isolates, somewhat surprisingly given the widespread availability of antibiotics without prescription. This genomic information provides important insights into the significance of S. Paratyphi B biotypes in enteric disease and their implications for public health.

Isolation, identification and toxinotyping of Clostridium perfringens isolated from broilers in Pakistan

Necrotic enteritis (NE) is one of the important enteric disease in the poultry industry worldwide, caused by C. perfringens type A. This study describes the isolation, identification, and toxinotyping of C. perfringens in necrotic enteritis affected broiler chicken in Pakistan. A total of 430 intestinal samples from dead carcasses and birds suspected of NE outbreak, in and around Faisalabad, Pakistan were collected from 36 broiler farms which yielded 87 alpha toxin gene (cpa) positive C. perfringens type A isolates. The birds having 4-5 weeks of age, clinical signs, and reared in open (conventional) sheds showed higher C. perfringens isolation rate. The study concluded netB negative C. perfringens type A as a causative agent for NE outbreaks in broiler birds in Faisalabad, Pakistan.

A Rapid and Simple Assay Correlates In Vitro NetB Activity with Clostridium perfringens Pathogenicity in Chickens

Necrotic enteritis is an important enteric disease in poultry, caused by NetB-producing Clostridium (C.) perfringens strains. As no straight-forward method to assess the NetB activity of C. perfringens was available, we aimed to develop an easy, high-throughput method to measure the NetB activity produced by C. perfringens. First, the appearance of C. perfringens on different avian blood agar plates was assessed. Based on the size of the haemolysis surrounding the C. perfringens colonies, NetB-positive strains could phenotypically be discriminated from NetB-negative strains on both chicken and duck blood agar. Additionally, strains producing the consensus NetB protein induced more pronounced haemolysis on chicken blood agar as compared to the weak outer haemolysis induced by A168T NetB-variant-producing C. perfringens strains. Next, a 96-well plate-based haemolysis assay to screen NetB activity in the C. perfringens culture supernatants was developed. Using this assay, a positive correlation between the in vitro NetB activity and virulence of the C. perfringens strains was shown. The developed activity assay allows us to screen novel C. perfringens isolates for their in vitro NetB activity, which could give valuable information on their disease-inducing potential, or identify molecules and (bacterial) metabolites that affect NetB expression and activity.