Yersiniosis is an infectious zoonotic disease caused by two enteropathogenic species of Gram-negative genus Yersinia: Yersinia enterocolitica and Yersinia pseudotuberculosis. Pigs and other wild and domestic animals are reservoirs for these bacteria. Infection is usually spread to humans by ingestion of contaminated food. Yersiniosis is considered a rare disease, but recent studies indicate that it is overlooked in the diagnostic process therefore the infections with this bacterium are not often identified. Reliable diagnosis of Yersiniosis by culturing is difficult due to the slow growth of the bacteria easily overgrown by other more rapidly growing microbes unless selective growth media is used. Phage adhesins recognizing bacteria in a specific manner can be an excellent diagnostic tool, especially in the diagnosis of pathogens difficult for culturing. In this study, it was shown that Gp17, the tail fiber protein (TFP) of phage φYeO3-12, specifically recognizes only the pathogenic Yersinia enterocolitica serotype O:3 (YeO:3) bacteria. The ELISA test used in this work confirmed the specific interaction of this protein with YeO:3 and demonstrated a promising tool for developing the pathogen recognition method based on phage adhesins.

Bifidobacteria are among the most common bacteria used for their probiotic properties and their impact on the maturation and function of the immune system has been well-described. Recently, scientific interest is shifting from live bacteria to defined bacteria-derived biologically active molecules. Their greatest advantage over probiotics is the defined structure and the effect independent of the viability status of the bacteria. Here, we aim to characterize Bifidobacterium adolescentis CCDM 368 surface antigens that include polysaccharides (PSs), lipoteichoic acids (LTAs), and peptidoglycan (PG). Among them, Bad368.1 PS was observed to modulate OVA-induced cytokine production in cells isolated from OVA-sensitized mice by increasing the production of Th1-related IFN-γ and inhibition of Th2-related IL-5 and IL-13 cytokines (in vitro). Moreover, Bad368.1 PS (BAP1) is efficiently engulfed and transferred between epithelial and dendritic cells. Therefore, we propose that the Bad368.1 PS (BAP1) can be used for the modulation of allergic diseases in humans. Structural studies revealed that Bad368.1 PS has an average molecular mass of approximately 9,99 × 10⁶ Da and it consists of glucose, galactose, and rhamnose residues that are creating the following repeating unit: →2)-β-D-Glcp-1→3-β-L-Rhap-1→4-β-D-Glcp-1→3-α-L-Rhap-1→4-β-D-Glcp-1→3-α-D-Galp-(1→_n.

Clinical and experimental cancer therapy is multifaceted; one such facet is the use of drug carriers. Drug carriers are various nano- and macromolecules, e.g., oligosaccharides, proteins, and liposomes. The present study aimed to verify the suitability of cellulose as a carrier for methotrexate (MTX). Hydroxyethylcellulose, with a molecular weight of 90 kDa and soluble in water, was used. Methotrexate was linked to cellulose by methyl ester bonds. A conjugate containing on average 9.5 molecules of MTX per molecule of cellulose was developed. Gel filtration HPLC analysis showed that the conjugate contained approximately 2% free drug. Dynamic light scattering analysis showed an increase in the polydispersity of the conjugate. The degradation of the conjugate in phosphate buffer and plasma followed first-order kinetics. The conjugate showed the lowest stability (half-life 154 h) in plasma. The conjugate showed 10-fold lower cytotoxicity to the 4 T1 mammary tumour cell line than the free drug. In the in vivo experiment to treat orthotopically implanted mammary tumours, the conjugate and the free drug, both applied intravenously, showed maximum inhibition of tumour growth of 48.4% and 11.2%, respectively. In conclusion, cellulose, which is a non-biodegradable chain glucose polymer, can be successfully used as a drug carrier, which opens up new research perspectives.

Type II thioesterases were shown to maintain efficiency of modular type I polyketide synthases and nonribosomal peptide synthetases by removing acyl residues blocking extension modules. We found that thioesterase ScoT from Streptomyces coelicolor A3(2) is required for the production of the yellow-pigmented coelimycin by the modular polyketide synthase Cpk. No production of coelimycin was observed in cultures of scoT disruption mutant. Polyketide production was restored upon complementation with an intact copy of the scoT gene. An enzymatic assay showed that ScoT thioesterase can hydrolyse a 12-carbon acyl chain but the activity is too low to play a role in product release from the polyketide synthase. We conclude that ScoT is an editing enzyme necessary to maintain the activity of polyketide synthase Cpk. We provide a HPLC based method to measure the amount of coelimycin P2 in a culture medium.

Rothia is an opportunistic pathogen, particularly life-threatening for the immunocompromised. It is associated with pneumonia, endocarditis, peritonitis and many other serious infections, including septicemia. Of note, Rothia mucilaginousa produces metabolites that support and increase overgrowth of Pseudomonas aeruginosa, one of the ESKAPE bacteria. Endolysins are considered as antibacterial enzymes derived from bacteriophages that selectively and efficiently kill susceptible bacteria without harming human cells or the normal microbiome. Here, we applied a computational analysis of metagenomic sequencing data of the gastric mucosa phageome extracted from human patients’ stomach biopsies. A selected candidate anti-Rothia sequence was produced in an expression system, purified and confirmed as a Rothia mucilaginosa- and Rothia dentocariosa-specific endolysin PolaR, able to destroy bacterial cells even when aggregated, as in a biofilm. PolaR had no cytotoxic or antiproliferative effects on mammalian cells. PolaR is the first described endolysin selectively targeting Rothia species, with a high potential to combat infections caused by Rothia mucilaginosa and Rothia dentocariosa, and possibly other bacterial groups. PolaR is the first antibacterial enzyme selected from the gastric mucosa phageome, which underlines the biological complexity and probably underestimated biological role of the phageome in the human gastric mucosa.

Canine B-cell lymphoma (CBL) is an incurable, spontaneous lymphoid malignancy constituting an accurate animal model for testing novel therapeutic strategies in human medicine. Resources of available species-specific therapeutic monoclonal antibodies (mAbs) targeting CBL are scarce. The aim of the present study was to evaluate the therapeutic potential of mAb B5, specific for the dog leukocyte antigen DR (DLA-DR) and its antibody-drug conjugate with methotrexate (B5-MTX). B5 induced caspase-dependent apoptosis of DLA-DR-expressing canine B cell lymphoma/CLBL1 and CLB70 leukemia lines, but not the GL-1 line not expressing DLA-DR. The cytotoxicity of B5-MTX to sensitive cells was further potentiated by a payload of MTX, but without any substantial off-target effects. The infusion of B5 and B5-MTX in a murine model of disseminated, advanced canine lymphoma, mediated >80% and >90% improvement in survival, respectively, and was well tolerated by the animals. Interestingly, the concentrations of soluble DLA-DR (sDLA-DR) antigens present in the blood serum of tumor-bearing mice were found proportional to the tumor burden. On this basis, sDLA-DR levels were evaluated as a potential biomarker using samples from canine lymphoma patients. In summary, the action of B5 and B5-MTX holds promise for further development as an alternative/complementary option for the diagnosis and treatment of canine lymphoma.