First molecular characterization of Burkholderia mallei strains isolated from horses in Mongolia.

Glanders, a highly contagious and often fatal disease affecting equids, is caused by Burkholderia mallei. Although sporadic cases of equine glanders have recently been documented in Mongolia, genome sequencing and molecular studies of the bacteria within this region are lacking. This study provided the first molecular characterization of B. mallei isolated from four native Mongolian horses from two different provinces in 2019 and 2022 by applying whole-genome sequencing with two SNP types (previously developed genotyping with 15 SNP markers that provide global coverage of the B. mallei population and the core genome coding SNP typing developed in this study). The Mongolian isolates were located within the L3B1 cluster, which was previously associated with the V-120 strain from Russia. Within the L3B1 cluster shared by neighboring countries, they were in a unique subbranch. In this study, specific SNP markers unique to the Mongolian strains were identified to track these strains using a high-resolution melting analysis (HRMA). This study revealed the unique phylogenetic background of Mongolian strains isolated from the eastern part of Mongolia. HRMA specific to the Mongolian subbranch may contribute to the molecular epidemiological monitoring of glanders in Mongolia and surrounding countries.

Systemic mucoid degeneration of the arterial tunica intima in a young dog.

A 27-mo-old, spayed female mixed-breed dog was presented with left forelimb pain, which progressed to full thickness necrosis of the soft tissues of multiple limbs. Clinical imaging and postmortem examination suggested multiple large arterial thromboemboli. Histologic examination of vascular lesions revealed markedly thickened tunica intima with polypoid intraluminal projections, which partially to entirely occluded the arterial lumen. The expanded tunica intima was comprised of intimal accumulation of Alcian blue-positive matrix with scattered spindle-to-satellite cells. These cells were positive for von Willebrand factor and vimentin but negative for α-smooth muscle actin, suggesting endothelial origin. Deposition of the intimal mucoid matrix was observed in the elastic and muscular arteries associated with regional ischemic changes. Mucoid emboli, likely from fragmentation of proliferative intimal tissue, were identified in smaller vessels supplied by affected arteries. Based on these findings, we diagnosed systemic mucoid degeneration of the arterial tunica intima. Such systemic arterial degeneration characterized by deposition of mucoid matrix in the tunica intima has not been reported previously in dogs, to our knowledge, and should be distinguished from thromboembolism and other degenerative vascular diseases.

Programmed death-ligand 1 expression in swine chronic infections and enhancement of interleukin-2 production via programmed death-1/programmed death-ligand 1 blockade.

INTRODUCTION: Chronic infections lead to the functional exhaustion of T cells. Exhausted T cells are phenotypically differentiated by the surface expression of the immunoinhibitory receptor, such as programmed death-1 (PD-1). The inhibitory signal is produced by the interaction between PD-1 and its PD-ligand 1 (PD-L1) and impairs the effector functions of T cells. However, the expression dynamics of PD-L1 and the immunological functions of the PD-1/PD-L1 pathway in chronic diseases of pigs are still poorly understood. In this study, we first analyzed the expression of PD-L1 in various chronic infections in pigs, and then evaluated the immune activation by the blocking assay targeting the swine PD-1/PD-L1 pathway. METHODS: In the initial experiments, anti-bovine PD-L1 monoclonal antibodies (mAbs) were tested for cross-reactivity with swine PD-L1. Subsequently, immunohistochemical analysis was conducted using the anti-PD-L1 mAb. Finally, we assessed the immune activation of swine peripheral blood mononuclear cells (PBMCs) by the blockade with anti-PD-L1 mAb. RESULTS: Several anti-PD-L1 mAbs tested recognized swine PD-L1-expressing cells. The binding of swine PD-L1 protein to swine PD-1 was inhibited by some of these cross-reactive mAbs. In addition, immunohistochemical analysis revealed that PD-L1 was expressed at the site of infection in chronic infections of pigs. The PD-L1 blockade increased the production of interleukin-2 from swine PBMCs. CONCLUSIONS: These findings suggest that the PD-1/PD-L1 pathway could be also involved in immunosuppression in chronic infections in pigs. This study provides a new perspective on therapeutic strategies for chronic diseases in pigs by targeting immunosuppressive pathways.

Expression Analysis of Canine CMTM6 and CMTM4 as Potential Regulators of the PD-L1 Protein in Canine Cancers.

Cancer is one of the most significant causes of death in dogs. Antibody drugs targeting the PD-1/PD-L1 axis represent a promising immunotherapy for both human and canine cancers. However, the regulation mechanisms of PD-L1 expression in canine cancers require further investigation to better understand the resistance mechanisms to anti-PD-L1 therapy. Recent reports have shown that CMTM6 and CMTM4 are critical regulators of PD-L1 protein expression in human cancer cells. By preventing PD-L1 from lysosome-mediated degradation, CMTM6 maintains PD-L1 expression on the cell surface. However, the literature has not reported on CMTM6 and CMTM4 in dogs, and their functions are completely unknown. To reveal a regulation mechanism of PD-L1 in canine cancers, this study firstly identified the gene sequences of CMTM6 and CMTM4. Then, the expression analysis of these proteins was performed by immunohistochemistry. Furthermore, the functions of CMTM6 and CMTM4 in regulating PD-L1 expression were examined by gene knockdown of CMTM6 and CMTM4. Canine CMTM6 and CMTM4 displayed high amino acid sequence identities compared with those of humans and mice. An immunohistochemical analysis using cross-reactive antibodies revealed that canine malignant melanoma and osteosarcoma express CMTM6, CMTM4, and PD-L1 simultaneously. Gene knockdown of CMTM6 and CMTM4 with RNA interference significantly reduced the cell surface expression of PD-L1 in a canine cell line. These results suggest that CMTM6 and CMTM4 are regulators of PD-L1 expression in canine cancers and could serve as potential therapeutic targets to enhance antitumor immunity.

Author Correction: Structure of two purple pigments, catechinopyranocyanidins A and B from the seed-coat of the small red bean, Vigna angularis.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Structure of two purple pigments, catechiopyranocyanidins A and B from the seed-coat of the small red bean, Vigna angularis.

The small red bean, Vigna angularis, is primarily used to produce the "an-paste" component of Japanese sweets. Through the manufacturing process, the red seed-coat pigment is transferred to the colorless "an-particles", imparting a purple color. However, the major pigment in the seed coat has not yet been identified, although it is historically presumed to be an anthocyanin. Here, we report the isolation and structural determination of two hydrophobic purple pigments in the seed coat via instrumental analysis and derivatization. The new pigments, catechinopyranocyanidins A and B, contain a novel pyranoanthocyanidin skeleton condensed with a catechin and cyanidin ring system, and no sugar moieties. Catechinopyranocyanidins A and B are diastereomers with a different configuration at the catechin moiety, and both are purple in color in strongly acidic-to-neutral media. Catechinopyranocyanidins A and B are very stable under dark conditions, but, labile to light and decompose to colorless compounds. Thus, these pigments exhibit quite different chemical properties compared to simple anthocyanidins.