Identification of fimbrial subunits in the genome of Trueperella pyogenes and association between serum antibodies against fimbrial proteins and uterine conditions in dairy cows

Uterine microbial ecology and disease in cattle: A review

Due to the critical contribution of the uterine-associated microbiota in reproductive health, physiology, and performance, culture-independent methods have been increasingly employed to unravel key aspects of microbial ecology in the uterus of cattle. Nowadays, we know that bacterial diversity is crucial to maintain uterine health, however, there is still no consensus on the exact composition of a healthy uterine microbiota (or eubiosis). Generally, loss of bacterial diversity (or dysbiosis) contributes to the development of uterine infections, associated with increased relative abundances of Bacteroides, Fusobacterium, Trueperella, and Porphyromonas. Uterine infections are highly prevalent and gravely influence the profitability of cattle operations, animal welfare, and public health. Thus, understanding the dynamics of uterine microbial ecology is essential to develop effective strategies focused on preventing and mitigating the adverse effects of uterine dysbiosis as well as assisting in the process of restoring the core, healthy uterine microbiota. The aim of this review is to summarize research conducted in the microbial ecology of bovine uteri. We discuss the origin of the uterine microflora of healthy cows and the factors influencing its composition. In addition, we review the biology of specific pathogens that are known to increase in abundance during the occurrence of uterine disease. Lastly, we provide an overview of the bacterial biofilm in the bovine endometrium, and we briefly summarize the rationale for the use of probiotics to prevent uterine disease in cattle.

Comparative Genome Analysis of 19 Trueperella pyogenes Strains Originating from Different Animal Species Reveal a Genetically Diverse Open Pan-Genome

Trueperella pyogenes is a Gram-positive opportunistic pathogen that causes severe cases of mastitis, metritis, and pneumonia in a wide range of animals, resulting in significant economic losses. Although little is known about the virulence factors involved in the disease pathogenesis, a comprehensive comparative genome analysis of T. pyogenes genomes has not been performed till date. Hence, present investigation was carried out to characterize and compare 19 T. pyogenes genomes originating in different geographical origins including the draftgenome of the first Indian origin strain T. pyogenes Bu5. Additionally, candidate virulence determinants that could be crucial for their pathogenesis were also detected and analyzed by using various bioinformatics tools. The pan-genome calculations revealed an open pan-genome of T. pyogenes. In addition, an inventory of virulence related genes, 190 genomic islands, 31 prophage sequences, and 40 antibiotic resistance genes that could play a significant role in organism's pathogenicity were detected. The core-genome based phylogeny of T. pyogenes demonstrates a polyphyletic, host-associated group with a high degree of genomic diversity. The identified core-genome can be further used for screening of drug and vaccine targets. The investigation has provided unique insights into pan-genome, virulome, mobiliome, and resistome of T. pyogenes genomes and laid the foundation for future investigations.

Tanshinone ⅡA inhibits the lipopolysaccharide-induced epithelial-mesenchymal transition and protects bovine endometrial epithelial cells from pyolysin-induced damage by modulating the NF-κB/Snail2 signaling pathway

Mixed infection with Escherichia coli and Trueperella pyogenes (T. pyogenes) leads to purulent endometritis, but the underlying molecular mechanisms remain unclear. The aim of this study was to investigate the effect of tanshinone ⅡA (Tan ⅡA) on E. coli and T. pyogenes -induced purulent endometritis and explore the underlying mechanism. First, lipopolysaccharide (LPS) isolated from E. coli and bacteria-free filtrates (BFFs) isolated from T. pyogenes were used to induce a model of bovine endometrial epithelial cell (bEEC) damage in vitro. bEECs were pretreated with or without Tan ⅡA for 2 h, before LPS and BFFs were introduced to induce damage to investigate the protective effect of Tan IIA. Then, the cytolytic activity and inflammatory response in bEECs were examined using CCK-8, LDH and RT-qPCR assays. Furthermore, we confirmed the molecular mechanism by which Tan ⅡA reversed the damaged phenotypes in LPS- and BFFs-induced bEECs via the NF-κB/Snail2 pathway using qPCR and Western blotting. Tan ⅡA significantly decreased the cytolytic activity and inflammatory response in LPS- and BFFs-induced bEECs. In addition, Tan ⅡA reversed the dysregulation of E-cadherin, N-cadherin and vimentin. Moreover, Tan ⅡA significantly inhibited the activation of the NF-κB signaling pathway and decreased the expression level of Snail2, which is the main regulator of the epithelial-mesenchymal transition (EMT). In summary, Tan ⅡA inhibits the LPS-induced EMT and protects bEECs from pyolysin-induced damage by modulating the NF-κB/Snail2 signaling pathway.

Clinical endometritis with Trueperella pyogenes reduces reproductive performance and milk production in dairy cows

The aim of this study was to identify the impact of Trueperella pyogenes in cows with clinical endometritis (CE) on reproductive performance and milk production in affected cows. In total, 230 lactating Holstein dairy cows from six commercial dairy herds were sampled once between 28 and 33 days post-partum. Cows included in the present study did not receive antibiotic or anti-inflammatory treatments prior to the experimental period. Clinical endometritis (CE) was characterized as cow with vaginal mucus score = 3 (>50% of purulent vaginal discharge) and >18% polymorphonuclear neutrophilic leukocyte (PMNL). The body condition scores (BCS) and milk production were evaluated at the time of enrolment. The identification of isolated bacteria was carried out through the analysis of MALDI-TOF MS (matrix-assisted laser desorption ionization time-of-flight mass spectrometry). According to uterine health, three groups of dairy cows were formed: healthy control cows without T. pyogenes (n = 147), CE cows with T. pyogenes (n = 22) and CE cows without T. pyogenes (n = 61). CE cows with T. pyogenes had lower BCS, milk production and conception at first AI (p < .01) than CE cows without T. pyogenes and control cows. Furthermore, CE cows with T. pyogenes had higher (p < .01) service per pregnancy and had greater (p < .01) days to get pregnant than CE cows without T. pyogenes and control cows. This study demonstrates that CE cows with T. pyogenes had impaired reproductive performance and milk production when compared to cows without CE and CE cows without T. pyogenes. This information can contribute to a strategic treatment in cows affected by clinical endometritis, favouring the rational use of antibiotics on dairy farms.

Trueperella pecoris sp. nov. isolated from bovine and porcine specimens

A novel Gram-stain-positive bacterium was isolated from a purulent bovine milk sample, the bovine placenta from an abortion, the udder secretion of a heifer and the lung of a pig that had succumbed from suppurative bronchopneumonia in Switzerland from 2015 to 2019. The strains grew best under aerobic conditions with 5 % CO₂ and colonies were non-haemolytic and greyish-white. They were non-motile and negative for catalase and oxidase. The genomes of the four strains 19M2397^T, 15A0121, 15IMD0307 and 19OD0592 were obtained by sequencing. The results of phylogenetic analyses based on the 16S rRNA gene grouped them within the genus Trueperella in the family Arcanobacteriaceae. The genomes had DNA G+C contents of 61.2-62.2 mol% and showed digital DNA-DNA hybridization (dDDH) values of 21.4-22.8 % and average nucleotide identity (ANI) values of approximately 77 % to their closest relatives Trueperella pyogenes and Trueperella bernardiae. With respect to the presence in different livestock species we propose the name Trueperella pecoris sp. nov. The type strain is 19M2397^T (=CCOS 1952^T=DSM 111392^T), isolated from the udder secretion of a heifer diagnosed with summer mastitis in 2019.

Pathogenicity and Virulence of Trueperella pyogenes: A Review

Bacteria from the species Trueperella pyogenes are a part of the biota of skin and mucous membranes of the upper respiratory, gastrointestinal, or urogenital tracts of animals, but also, opportunistic pathogens. T. pyogenes causes a variety of purulent infections, such as metritis, mastitis, pneumonia, and abscesses, which, in livestock breeding, generate significant economic losses. Although this species has been known for a long time, many questions concerning the mechanisms of infection pathogenesis, as well as reservoirs and routes of transmission of bacteria, remain poorly understood. Pyolysin is a major known virulence factor of T. pyogenes that belongs to the family of cholesterol-dependent cytolysins. Its cytolytic activity is associated with transmembrane pore formation. Other putative virulence factors, including neuraminidases, extracellular matrix-binding proteins, fimbriae, and biofilm formation ability, contribute to the adhesion and colonization of the host tissues. However, data about the pathogen–host interactions that may be involved in the development of T. pyogenes infection are still limited. The aim of this review is to present the current knowledge about the pathogenic potential and virulence of T. pyogenes.

Determination of the expression of three fimbrial subunit proteins in cultured Trueperella pyogenes

Background

Trueperella pyogenes is a commensal and a significant opportunistic pathogen in animals. A variety of identified or putative virulence factors are considered to significantly contribute to the occurrence of T. pyogenes infection in different species. However, these virulence factors are not fully understood.

Results

In the current study, the genes encoding putative fimbrial proteins, i.e. Fim A, Fim C, and Fim E, were cloned. Recombinant Fim A (rFim A), Fim C (rFim C), and Fim E (rFim E) were prepared and used to generate rabbit anti-rFim A, anti-rFim C, and anti-rFim E serum, respectively. Using these sera, we found that only Fim E was constitutively expressed in T. pyogenes. The expression level of Fim E in T. pyogenes peaked within 6–10 h of culture period in pH 7.5. Fim E protein expression was unaffected by anaerobic condition, but was inhibited by the microaerophilic condition. Tube agglutination tests indicated that Fim E was exhibited on the surface of T. pyogenes cells because anti-rFim E serum caused strong agglutination. Additionally, the blots for Fim A detection showed nonspecific reactions. Furthermore, the tube agglutination tests showed that anti-Fim A serum failed to cause agglutination of T. pyogenes cells, which indicated that Fim A was not, or poorly, expressed in cultured T. pyogenes. Anti-rFim C serum caused strong agglutination. However, the blots for Fim C detection showed a strong nonspecific reaction. Thus, the expression of Fim C was difficult to be determined using the current method.

Conclusions

Fim E was expressed in cultured T. pyogenes. However, Fim A was either not or poorly expressed in cultured T. pyogenes. Moreover, Fim C expression was not determined using the current strategy.

Electronic supplementary material

The online version of this article (10.1186/s13028-018-0407-3) contains supplementary material, which is available to authorized users.

Chitosan-DNA nanoparticles enhanced the immunogenicity of multivalent DNA vaccination on mice against Trueperella pyogenes infection

BACKGROUND

Trueperella pyogenes is a commensal and opportunistic pathogen that normally causes mastitis, liver abscesses and pneumonia of economically important livestock. To develop efficacious and potent vaccine against T. pyogenes, chimeric gene DNA vaccines were constructed and encapsulated in chitosan nanoparticles (pPCFN-CpG-CS-NPs).

RESULTS

The pPCFN-CpG-CS-NPs consists of the plo, cbpA, fimA, and nanH gene of T. pyogenes and CpG ODN1826. It was produced with good morphology, high stability, a mean diameter of 93.58 nm, and a zeta potential of + 5.27 mV. Additionally, chitosan encapsulation was confirmed to protect the DNA plasmid from DNase I digestion. The immunofluorescence assay indicated that the four-chimeric gene could synchronously express in HEK293T cells and maintain good bioactivity. Compared to the mice immunized with the control plasmid, in vivo immunization showed that mice immunized with the pPCFN-CpG-CS-NPs had better immune responses, and release of the plasmid DNA was prolonged. Importantly, immunization with pPCFN-CpG-CS-NPs could significantly protect mice from highly virulent T. pyogenes TP7 infection.

CONCLUSIONS

This study indicates that chitosan-DNA nanoparticles are potent immunization candidates against T. pyogenes infection and provides strategies for the further development of novel vaccines encapsulated in chitosan nanoparticles.

Bovine Endometrial Epithelial Cells Scale Their Pro-inflammatory Response In vitro to Pathogenic Trueperella pyogenes Isolated from the Bovine Uterus in a Strain-Specific Manner

Among different bacteria colonizing the bovine uterus, Trueperella pyogenes is found to be associated with clinical endometritis (CE). The ability of cows to defend against T. pyogenes infections depends on the virulence of invading bacteria and on the host's innate immunity. Therefore, to gain insights into bacterial factors contributing to the interplay of this host pathogen, two strains of T. pyogenes were included in this study: one strain (TP2) was isolated from the uterus of a postpartum dairy cow developing CE and a second strain (TP5) was isolated from a uterus of a healthy cow. The two strains were compared in terms of their metabolic fingerprints, growth rate, virulence gene transcription, and effect on bovine endometrial epithelial cells in vitro. In addition, the effect of the presence of peripheral blood mononuclear cells (PBMCs) on the response of endometrial epithelial cells was evaluated. TP2, the strain isolated from the diseased cow, showed a higher growth rate, expressed more virulence factors (cbpA, nanH, fimE, and fimG), and elicited a higher mRNA expression of pro-inflammatory factors (PTGS2, CXCL3, and IL8) in bovine endometrial epithelial cells compared with TP5, the strain isolated from the healthy cow. The presence of PBMCs amplified the mRNA expression of pro-inflammatory factors (PTGS2, CXCL3, IL1A, IL6, and IL8) in bovine endometrial epithelial cells co-cultured with live TP2 compared with untreated cells, especially as early as after 4 h. In conclusion, particular strain characteristics of T. pyogenes were found to be important for the development of CE. Furthermore, immune cells attracted to the site of infection might also play an important role in up-regulation of the pro-inflammatory response in the bovine uterus and thus significantly contribute to the host-pathogen interaction.

A combined Clostridium perfringens/Trueperella pyogenes inactivated vaccine induces complete immunoprotection in a mouse model

Clostridium perfringens (C. perfringens) and Trueperella pyogenes (T. pyogenes) are two bacterial pathogens frequently associated with wound infections and following lethal complications in livestock. However, prudent use of antimicrobial agents is highly required given the emergence of multidrug-resistant strains of both bacteria and need for food safety. In the current study, a combined vaccine, composed of inactivated C. perfringens and T. pyogenes, was prepared. The amount of formaldehyde being used to inactivate two bacteria was optimized to retain the immunogenicity of antigens. Three adjuvants were tested for their potency in improving specific immune responses against the candidate antigens. Then inactivated combined C. perfringens/T. pyogenes vaccine was prepared using inactive cultures of two organisms. The ratio of inactive cultures of two organisms for preparation of combined vaccine was optimized to gain effective protective immunity against the two pathogens. Results revealed that combined C. perfringens/T. pyogenes inactive vaccine can elicit high level of exotoxins and cell-associated antigen-specific antibodies and induce complete protection against C. perfringens and T. pyogenes infections in mice. The combined vaccine could be used as an alternative of antibiotics for prevention of C. perfringens and T. pyogenes infections in animals.