A study on the efficacy of the recombinant Yersinia adhesin A vaccine against yersiniosis in the early phase

Yersinia pseudotuberculosis in Non-Domesticated Mammals and Birds in Captivity

Yersinia pseudotuberculosis causes yersiniosis in a wide range of mammalian and avian taxa worldwide. This review aims to provide an overview of the current literature on yersiniosis in non-domesticated mammals and birds in captivity. Data on the prevalence of Y. pseudotuberculosis in captive populations are scarce. Transmission is primarily via the fecal-oral route, with wild rodents and birds as primary reservoirs. Predisposing factors to yersiniosis include young age, inclement weather, stress, and genetic factors. Symptoms are often non-specific, with sudden death occurring frequently, particularly in avian species. Gross pathological examination typically reveals multiple white-yellow foci in visceral organs, while histopathology demonstrates necrosis with central bacterial colonies. Ante-mortem diagnosis can be challenging as bacterial culture and isolation from fecal samples are often hindered by intermittent excretion and competition with other gastrointestinal flora. Although killed and subunit vaccine formulations have demonstrated limited protective efficacy, live attenuated strains may hold greater promise for inducing more robust and durable immunity. Y. pseudotuberculosis remains a significant threat to animal health, highlighting the need for faster and more reliable diagnostic techniques and the development of more effective treatment and prophylactic strategies.

Type 5 secretion system antigens as vaccines against Gram-negative bacterial infections

Infections caused by Gram-negative bacteria are leading causes of mortality worldwide. Due to the rise in antibiotic resistant strains, there is a desperate need for alternative strategies to control infections caused by these organisms. One such approach is the prevention of infection through vaccination. While live attenuated and heat-killed bacterial vaccines are effective, they can lead to adverse reactions. Newer vaccine technologies focus on utilizing polysaccharide or protein subunits for safer and more targeted vaccination approaches. One promising avenue in this regard is the use of proteins released by the Type 5 secretion system (T5SS). This system is the most prevalent secretion system in Gram-negative bacteria. These proteins are compelling vaccine candidates due to their demonstrated protective role in current licensed vaccines. Notably, Pertactin, FHA, and NadA are integral components of licensed vaccines designed to prevent infections caused by Bordetella pertussis or Neisseria meningitidis. In this review, we delve into the significance of incorporating T5SS proteins into licensed vaccines, their contributions to virulence, conserved structural motifs, and the protective immune responses elicited by these proteins.

Case report: First isolation of Yersinia pseudotuberculosis from the blood of a cat

A 14-year-old female domestic short-haired cat with a diagnosed diabetes mellitus and acromegaly was presented for lethargy and dysorexia. On clinical presentation, the patient showed hyperglycemia, hyperthermia, dull mentation, and dehydration. With the suspicion of an inflammatory or infectious complication of diabetes, she was hospitalized with constant rate infusion of insulin, and empirical ampicillin sulbactam was started. Blood culture revealed positivity for Yersinia pseudotuberculosis and the septic picture was confirmed by blood analysis, with leukocytosis, neutrophilia, and an increased serum amyloid A concentration. The isolated Y. pseudotuberculosis strain showed susceptibility to every antimicrobial tested. During the second day of hospitalization, the onset of hypoglycemia and hypotension was treated with norepinephrine and glucose in fluid therapy. The cat recovered well and was discharged with insulin and amoxicillin-clavulanate. This is the first case of septicemia associated with Y. pseudotuberculosis in a cat, suspected of developing the infection after contact with natural reservoirs such as rodents or birds. This route of transmission should be highlighted especially in relation to the zoonotic potential of the bacteria.

An Update in Knowledge of Pigs as the Source of Zoonotic Pathogens

The available data indicate that the human world population will constantly grow in the subsequent decades. This constant increase in the number of people on the Earth will lead to growth in food demand, especially in food of high nutritional value. Therefore, it is expected that the world livestock population will also increase. Such a phenomenon enhances the risk of transmitting pathogens to humans. As pig production is one of the most significant branches of the world's livestock production, zoonoses of porcine origins seem to be of particular importance. Therefore, in this review, we aim to introduce the latest data concerning, among other things, epidemiology and available preventive measures to control the most significant porcine zoonoses of viral, bacterial, and parasitic origin.

Genomic Analysis of Pasteurella atlantica Provides Insight on Its Virulence Factors and Phylogeny and Highlights the Potential of Reverse Vaccinology in Aquaculture

Pasteurellosis in farmed lumpsuckers, Cyclopterus lumpus, has emerged as a serious disease in Norwegian aquaculture in recent years. Genomic characterization of the causative agent is essential in understanding the biology of the bacteria involved and in devising an efficient preventive strategy. The genomes of two clinical Pasteurella atlantica isolates were sequenced (≈2.3 Mbp), and phylogenetic analysis confirmed their position as a novel species within the Pasteurellaceae. In silico analyses revealed 11 genomic islands and 5 prophages, highlighting the potential of mobile elements as driving forces in the evolution of this species. The previously documented pathogenicity of P. atlantica is strongly supported by the current study, and 17 target genes were recognized as putative primary drivers of pathogenicity. The expression level of a predicted vaccine target, an uncharacterized adhesin protein, was significantly increased in both broth culture and following the exposure of P. atlantica to lumpsucker head kidney leucocytes. Based on in silico and functional analyses, the strongest gene target candidates will be prioritized in future vaccine development efforts to prevent future pasteurellosis outbreaks.

Analysis of Yersinia pseudotuberculosis Isolates Recovered from Deceased Mammals of a German Zoo Animal Collection

Yersinia pseudotuberculosis is an important pathogen for both humans and animals. It can infect livestock, as well as pets and wild animals. During recent years, a number of reports have described the isolation of Y. pseudotuberculosis from zoo animals, mainly birds and mammals, for which the infection was mostly lethal. Between 2005 and 2019, there were at least 17 cases of deceased mammals, belonging to five different species, which suffered from a Y. pseudotuberculosis infection at the Zoo Wuppertal, Germany. Since only scarce information exists on the properties of Y. pseudotuberculosis from zoo animals, we characterized eight isolates, covering all infected species, in detail. All isolates were members of biotype 1, but belonged to five serotypes, five sequence types (STs), and seven core-genome multilocus sequence types (cgMLSTs). Using pulsed-field gel electrophoresis (PFGE) analysis and whole-genome sequencing (WGS), the seven isolates could be discriminated from each other. They differed significantly regarding their virulence genes and mobile genetic elements. While the virulence plasmid pYV existed in all serotypes (five isolates), a complete high-pathogenicity island (HPI) was detected only in the serotypes O:1a, O:1b, and O:13 (four isolates), but not in O:2a and O:2b. Similarly, the content of other plasmids and prophages varied greatly between the isolates. The data demonstrate that the deceased mammals were infected by seven individual isolates and not by a single type predominating in the zoo animals.

Immunogenicity of trimeric autotransporter adhesins and their potential as vaccine targets

The current problem of increasing antibiotic resistance and the resurgence of numerous infections indicate the need for novel vaccination strategies more than ever. In vaccine development, the search for and the selection of adequate vaccine antigens is the first important step. In recent years, bacterial outer membrane proteins have become of major interest, as they are the main proteins interacting with the extracellular environment. Trimeric autotransporter adhesins (TAAs) are important virulence factors in many Gram-negative bacteria, are localised on the bacterial surface, and mediate the first adherence to host cells in the course of infection. One example is the Neisseria adhesin A (NadA), which is currently used as a subunit in a licensed vaccine against Neisseria meningitidis. Other TAAs that seem promising vaccine candidates are the Acinetobacter trimeric autotransporter (Ata), the Haemophilus influenzae adhesin (Hia), and TAAs of the genus Bartonella. Here, we review the suitability of various TAAs as vaccine candidates.

Subtractive proteomics and immunoinformatics revealed novel B-cell derived T-cell epitopes against Yersinia enterocolitica: An etiological agent of Yersiniosis

Yersinia enterocolitica is the third most common cause of gastrointestinal manifestations in Europe. Statistically, every year the pathogen accounts for 640 hospitalizations, 117,000 illnesses, and 35 deaths in the United States. The associated mortality rate of the pathogen is 50% and is virtually resistant to penicillin G, ampicillin and cephalotin. The development of new and effective therapeutic procedures is urgently needed to counter the multi-drug-resistant phenotypes imposed by the said pathogen. Based on subtractive reverse vaccinology and immunoinformatics approaches, we have successfully predicted novel antigenic peptide vaccine candidates against Y. enterocolitica. The pipeline revealed two isoforms of ompC family; meoA (ompC) and ompC2 as promising vaccine targets. Protein-protein interactions elaborated the involvement of target candidates in the major biological pathways of the pathogen. The predicted 9-mer B-cell derived T-cell epitope of proteins are found to be virulent, antigenic, non-allergic, surface exposed and conserved in all nine completely sequenced strains of the pathogen. Molecular docking predicts deep and stable binding of the epitopes in the binding pocket of the most predominant allele in human population-the DRB1*0101. These epitopes of target proteins could provide the foundation for the development of an epitope-driven vaccine against Y. enterocolitica.