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Pasteurella multocida is a leading cause of respiratory disorders in pigs. However, the genotypes and antimicrobial resistance characteristics of P. multocida from pigs in China have not been reported frequently. In this study, we investigated 381 porcine strains of P. multocida collected in China between 2013 and 2022. These strains were assigned to capsular genotypes A (69.55%, n = 265), D (27.82%, n =106), and F (2.62%, n = 10); or lipopolysaccharide genotypes L1 (1.31%, n = 5), L3 (24.41%, n = 93), and L6 (74.28%, n = 283). Overall, P. multocida genotype A:L6 (46.46%) was the most-commonly identified type, followed by D:L6 (27.82%), A:L3 (21.78%), F:L3 (2.62%), and A:L1 (1.31%). Antimicrobial susceptibility testing showed that a relatively high proportion of strains were resistant to tetracycline (66.67%, n = 254), and florfenicol (35.17%, n = 134), while a small proportion of strains showed resistance phenotypes to enrofloxacin (10.76%, n = 41), ampicillin (8.40%, n = 32), tilmicosin (7.09%, n = 27), and ceftiofur (2.89%, n = 11). Notably, Illumina short-read and Nanopore long-read sequencing identified a chromosome-borne tigecycline-resistance gene cluster tmexCD3-toprJ1 in P. multocida. The structure of this cluster was highly similar to the respective structures found in several members of Proteus or Pseudomonas. It is assumed that the current study identified the tmexCD3-toprJ1 cluster for the first time in P. multocida., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

As the major outer membrane protein (OMP) presents in the Pasteurella multocida envelope, OmpH was frequently expressed for laboratory assessments of its immunogenicity against P. multocida infections, but the results are not good. In this study, we modified OmpH with dendritic cell targeting peptide (Depeps) and/or Salmonella FliCd flagellin, and expressed three types of recombinant proteins with the MBP tag (rDepeps-FliC-OmpH-MBP, rDepeps-OmpH-MBP, rFliC-OmpH-MBP). Assessments in mouse models revealed that vaccination with rDepeps-FliC-OmpH-MBP, rDepeps-OmpH-MBP, or rFliC-OmpH-MBP induced significant higher level of antibodies as well as IFN-γ and IL-4 in murine sera than vaccination with rOmpH-MBP (P < 0.5). Vaccination with the three modified proteins also provided increased protection (rDepeps-FliC-OmpH-MBP, 70 %; rDepeps-OmpH-MBP, 50 %; rFliC-OmpH-MBP, 60 %) against P. multocida serotype D compared to vaccination with rOmpH-MBP (30 %). In mice vaccinated with different types of modified OmpHs, a significantly decreased bacterial strains were recovered from bloods, lungs, and spleens compared to rOmpH-MBP-vaccinated mice (P < 0.5). Notably, our assessments also demonstrated that vaccination with rDepeps-FliC-OmpH-MBP provided good protection against infections caused by a heterogeneous group of P. multocida serotypes (A, B, D). Our above findings indicate that modification with DCpep and Salmonella flagellin could be used as a promising strategy to improve vaccine effectiveness., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Dermonecrotic toxin (DNT) is an important bacterial virulence factor produced by the zoonotic pathogens Bordetella bronchiseptica and Pasteurella multocida. This study aims to explore the possibility of expressing different fragments of P. multocida toxin (PMT) in the chromosome of attenuated B. bronchiseptica to generate single-component mucosal vaccine candidates. To achieve this, a 954-bp fragment (basepairs 301 ∼ 1254) of the B. bronchiseptica aroA gene was replaced with an N-terminal, 930-bp fragment (basepairs 1-930; PMTN) or a C-terminal, 900-bp fragment (base pairs 2959 ∼ 3858; PMTC) of the PMT encoding gene toxA. The resulting strains, denoted as Bb-PMTN or Bb-PMTC, expressed PMTN and PMTC, as evidenced by ELISA using polyclonal against full-length of PMT. Phenotypical analyses revealed that Bb-PMTN and Bb-PMTC grew much slower than wild type strains in tryptic soy broth. These strains also displayed significantly decreased 161-fold-virulence compared to the wildtype strains in mouse models. Intranasal immunization of Bb-PMTN and Bb-PMTC in mice induced high levels of antibodies against B. bronchiseptica and PMT, as well as IFN-γ and IL-10 in mouse sera, and most importantly, high titers of sIgA in mouse lungs. Vaccination with these two engineering strains provided 100% protection of mice against lethal challenge with B. bronchiseptica and 80%∼100% protection against lethal challenge with PMT, with Bb-PMTN exhibiting 1.25-fold greater immunogenic efficacy over Bb-PMTC. This study highlights the use of B. bronchiseptica attenuated strains as live mucosal vectors to deliver heterologous antigens., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Pasteurella multocida is an important zoonotic pathogen that causes multiple diseases in both animals and humans. Test of good immunogenic proteins is beneficial for vaccine development and disease control. In the present study, we determined four novel immunogenic proteins of P. multocida by using 2-DE MALDI-TOF MS with immune serum. These four proteins included a trimethylamine-N-oxide reductase TorA, a translation elongation factor Ts, a phosphoglyceromutase PGAM, and a peroxiredoxin PrX. Among these proteins, TorA, Prx, and PGAM were successfully expressed by using E. coli. Western-blotting assays showed that recombinant TorA, Prx, and/or PGAM displayed good reactions with infectious sera of P. multocida serogroups A, B, D and F. Immunization of either rTorA, rPrx, and/or rPGAM induced significantly high levels of antibodies as well as IFN-γ, IL-4 and IL-10 in mice (P < 0.01). Protective efficacy tests revealed that vaccination of either rTorA, rPrx, and/or rPGAM protected 60% ~ 80% of the tested mice against the challenge with P. multocida field isolate. Our results obtained from the present study suggest that these three proteins could be tested as good vaccine candidates against P. multocida infections., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Pasteurella multocida is a highly versatile pathogen capable of causing infections in a wide range of domestic and wild animals as well as in humans and nonhuman primates. Despite over 135 years of research, the molecular basis for the myriad manifestations of P. multocida pathogenesis and the determinants of P. multocida phylogeny remain poorly defined. The current availability of multiple P. multocida genome sequences now makes it possible to delve into the underlying genetic mechanisms of P. multocida fitness and virulence. Using whole-genome sequences, the genotypes, including the capsular genotypes, lipopolysaccharide (LPS) genotypes, and multilocus sequence types, as well as virulence factor-encoding genes of P. multocida isolates from different clinical presentations can be characterized rapidly and accurately. Putative genetic factors that contribute to virulence, fitness, host specificity, and disease predilection can also be identified through comparative genome analysis of different P. multocida isolates. However, although some knowledge about genotypes, fitness, and pathogenesis has been gained from the recent whole-genome sequencing and comparative analysis studies of P. multocida , there is still a long way to go before we fully understand the pathogenic mechanisms of this important zoonotic pathogen. The quality of several available genome sequences is low, as they are assemblies with relatively low coverage, and genomes of P. multocida isolates from some uncommon host species are still limited or lacking. Here, we review recent advances, as well as continuing knowledge gaps, in our understanding of determinants contributing to virulence, fitness, host specificity, disease predilection, and phylogeny of P. multocida ., (Copyright © 2019 American Society for Microbiology.)

A lytic bacteriophage PHB01 specific for Pasteurella multocida type D was isolated from the sewage water collected from a pig farm. This phage had the typical morphology of the family Podoviridae , order Caudovirales , presenting an isometric polyhedral head and a short noncontractile tail. PHB01 was able to infect most of the non-toxigenic P. multocida type D strains tested, but not toxigenic type D strains and those belonging to other capsular types. Phage PHB01, the first lytic phage specific for P. multocida type D sequenced thus far, presents a 37,287-bp double-stranded DNA genome with a 223-bp terminal redundancy. The PHB01 genome showed the highest homology with that of PHB02, a lytic phage specific for P. multocida type A. Phylogenetic analysis showed that PHB01 and PHB02 were composed of a genus that was close to the T7-virus genus. In vivo tests using mouse models showed that the administration of PHB01 was safe to the mice and had a good effect on treating the mice infected with different P. multocida type D strains including virulent strain HN05. These findings suggest that PHB01 has a potential use in therapy against infections caused by P. multocida type D.

Pasteurella multocida is a leading cause of respiratory disease in pigs worldwide. In this study, we determined the genetic characteristics of 115 P. multocida isolates from the lungs of pigs with respiratory disease in China in 2015 using capsular typing, lipopolysaccharide (LPS) genotyping, and virulence genotyping based on the detection of virulence-associated genes. The results showed that the isolates belonged to three capsular types: A (49.6%), D (46.1%), and nontypable (4.3%); and two LPS genotypes: L3 (22.6%) and L6 (77.4%). When combining the capsular types with the LPS genotypes, a genotype group D: L6 (46.1%) was the most prevalent among the strains. Among the 23 virulence-associated genes detected in this study, a small number of them displayed a certain level of "genotype-preference". We found that pfhA, hgbA, and hgbB had a close association with P. multocida LPS genotypes, while tadD was more associated with P. multocida capsular types. In addition, multilocus sequence typing (MLST) on 40 P. multocida isolates identified four sequence types: ST3, ST10, ST11, and ST16, and the distribution of ST11 was significantly higher than the other MLST genotypes. Interestingly, all of the ST11 isolates detected in this study were genotype D: L6 strains and they were 100% positive for hgbB. Our data suggest that a capsule/LPS/MLST genotype D/L6/ST11 is likely to be strongly associated with respiratory clinical manifestation of the disease in pigs.

Pasteurella multocida: subspecies multocida, gallicida, and septica are noted to have a contribution to fowl cholera, a life-threatening disease to both domestic and wild bird species. The genome sequences of avian P. multocida subspecies gallicida and multocida have been well analyzed and compared. However, the genome characterization of avian P. multocida subspecies septica is rarely discussed. In this study, we determined the draft genome sequence of a virulent P. multocida subspecies septica serogroup A strain HB02. The genome of P. multocida HB02 was composed of a single chromosome of 2,213,604 bp with a 40.27% G + C content, which showed a similar genome size and %GC content to the P. multocida subspecies multocida and gallicida genomes. The entire sequence specified 2002 putative coding DNA sequences plus 2 encoded rRNAs and 46 encoded tRNAs. In addition, the subspecies septica had a similar content of genes coding for metabolic traits that found in the subspecies gallicida and multocida. In addition, comparison of virulent versus avirulent avian P. multocida genomes identified 657 unique genes in either of the virulent strains HB02, P1059 and/or X73 compared to the avirulent strain Pm70. These genes should be the potential virulence-associated genes. Our work may add a novel genome sequence for the avian P. multocida genome database and shed a light on the pathogenesis of P. multocida.

Pasteurella multocida serotype F isolates are predominately prevalent in avian hosts, but rarely seen in pigs. However, we isolated several strains of P. multocida serotype F from clinical samples of pigs in China. To understand the pathogenicity of these strains, one of the serotype F isolates designated HN07, was used to challenge experimental chickens, as P. multocida of this serotype is predominately prevalent in avian hosts. However, strain HN07 could not resulted in significant clinical signs in experimental chickens even at an infective dose of ∼10 9 CFU, suggesting the isolate was avirulent to chickens and therefore raising the possibility that the porcine serotype F isolate is not transmitted by chickens. We then used HN07 to challenge experimental pigs, as this strain was isolated from pigs. As expected, the strain led to the clinical signs and the pathological lesions in experimental pigs that are similar to the pasteurellosis disease. We then determined the complete genome sequence of the pig origin serogroup F isolate HN07 for the first time. Genome comparison between HN07 and the avian serotype F P. multocida Pm70 identified a novel integrative conjugative element (ICE) ICEpmcn07 which was likely to harbor a series of genes responsible for a putative type IV secretion system (T4SS) in HN07. This is the first time that we determined an ICE carrying a T4SS in P. multocida. Besides, comparative analysis also defined a number of virulence-associated genes in HN07 but absent in Pm70 which may have a contribution to the pathogenicity of the strain. This is the first report of the pathogenicity and genome characterization of a pig origin Pasteurella multocida serogroup F isolate. The pathogenic and genomic definition of the pig origin P. multocida serogroup F in our study would have significance on the pathogenesis and genetic diversity and virulence variability of P. multocida., (Copyright © 2016. Published by Elsevier B.V.)

Pasteurella multocida infects various domestic and feral animals, generally causing clinical disease. To investigate P. multocida disease in cattle, we sequenced the complete genome of P. multocida HB01 (GenBank accession CP006976), a serotype A organism isolated from a cow in China. The genome is composed of a single circular chromosome of 2,416,068 base pairs containing 2212 protein-coding sequences, 6 ribosomal rRNA operons, and 56 tRNA genes. The present study confirms that P. multocida HB01 possesses a more complete metabolic pathway with an intact trichloroacetic acid cycle for anabolism compared with A. pleuropneumoniae and Haemophilus parasuis. This is the first time that this metabolic mechanism of P. multocida has been described. We also identified a full spectrum of genes related to known virulence factors of P. multocida. The differences in virulence factors between strains of different serotypes and origins were also compared. This comprehensive comparative genome analysis will help in further studies of the metabolic pathways, genetic basis of serotype, and virulence of P. multocida., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Pasteurella multocida is a leading cause of respiratory diseases in many host species. To understand the genetic characteristics of P. multocida strains isolated from different host species, we sequenced the genomic DNA of P. multocida isolated from pigs and analyzed the genetic characteristics of strains from avian species, bovine species, pigs, and rabbits using whole genome sequence (WGS) data. Our results found that a capsular: lipopolysaccharide (LPS): multilocus sequence typing (MLST) genotype A: L1: ST129 (43.75%) was predominant in avian P. multocida; while genotypes B: L2: ST122 (60.00%) and A: L3: ST79 (30.00%) were predominate in bovine P. multocida; genotype D: L6: ST50 (37.50%) in porcine P. multocida; and genotype A: L3: ST9 (76.47%) in rabbit P. multocida. Comparative genomic analysis of P. multocida from different host species found that there are no genes in the P. multocida genome that are specific to any type of host. Phylogenetic analysis using either whole-genome single nucleotide polymorphisms (SNPs) or the set of SNPs present in all single-copy core genes across genomes showed that P. multocida strains with the same LPS genotype and MLST genotype were clustered together, suggesting the combining both the LPS and MLST typing schemes better explained the topology seen in the P. multocida phylogeny. [ABSTRACT FROM AUTHOR]