Biology subjects

Kastelic, J. P.

Publications and source records attributed to Kastelic, J. P..

2 recordsLinked to original sources

bioRxiv2022

Comparative genomic analyses of Lactococcus garvieae isolated from bovine mastitis in China

Lactococcus garvieae is an emerging zoonotic pathogen, but there are few reports regarding bovine mastitis. The recent prevalence of L. garvieae poses an increasing disease threat and global public health risk. A total of 39 L. garvieae isolates were obtained from 2899 bovine clinical mastitis milk samples in 6 provinces of China from 2017 to 2021. Five clonal complexes were determined from 32 MLST types of L. garvieae; ST46 was the predominant sequence type and 13 novel MLST types were identified. All isolates were resistant to chloramphenicol and clindamycin, but susceptible to penicillin, ampicillin, amoxicillin-clavulanic acid, imipenem, ceftiofur, enrofloxacin, and marbofloxacin. Based on genomic analyses, L. garvieae had 6310 genes, including 1015, 3641 and 1654 core, accessory and unique genes. All isolates had virulence genes coding for collagenase, fibronectin-binding protein, Glyceraldehyde-3-phosphate dehydrogenase, superoxide dismutase and NADH oxidase. Most isolates had lsaD and mdtA AMR genes. Based on COG results, the functions of defense, transcription and replication, recombination and repair were enhanced in unique genes, whereas functions of translation, ribosomal structure and biogenesis were enhanced in core genes. The KEGG functional categories enriched in unique genes included human disease and membrane transport, whereas COG functional categories enriched in core genes included energy metabolism, nucleotide metabolism and translation. No gene was significantly associated with host specificity. In addition, core genome SNPs analysis suggested potential host adaptation of some isolates in several sequence types. Therefore, this study characterized L. garvieae isolated from mastitis and assessed host adaptation of L. garvieae to various hosts. IMPORTANCEThis study provides important insights on bovine mastitis key topic pathogen Lactococcus garvieae, which constitutes mastitis concerns. However, comprehensive genomic analyses of L. garvieae from dairy farms have not been performed. This study gives a detailed and comprehensive novel feature in L. garvieae, an important but poorly characterized bacterium, recovered in the past 5 years in 6 Chinese provinces. We documented diverse contributory genetic processes, including predominant sequence type ST46 and 13 novel MLST types. L. garvieae had 6310 genes, including 1015, 3641 and 1654 core, accessory and unique genes. All isolates had virulence genes coding for collagenase, fibronectin-binding protein, Glyceraldehyde-3-phosphate dehydrogenase, superoxide dismutase and NADH oxidase, and resistant to chloramphenicol and clindamycin. Most isolates had lsaD and mdtA antimicrobial resistance genes. No gene was significantly associated with host specificity. This is the first absolute quantification of L. garvieae isolated from mastitis and identified host adaptation of L. garvieae to various hosts.

microbiology↗

bioRxiv2019

Prototheca zopfii Genotype II induces mitochondrial apoptosis in models of bovine mastitis

Prototheca zopfii is an alga increasingly isolated from bovine mastitis. Of the two genotypes of P. zopfii (genotype I and II (GT-I and II)), P. zopfii GT-II is the genotype associated with acute mastitis and decreased milk production by unknown mechanisms. The objective was to determine inflammatory and apoptotic roles of P. zopfii GT-II in cultured mammary epithelial cells (from cattle and mice) and murine macrophages and using a murine model of mastitis. Prototheca zopfii GT-II (but not GT-I) invaded bovine and murine mammary epithelial cells (MECs) and induced apoptosis, as determined by the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labeling assay. This P. zopfii GT-II driven apoptosis corresponded to mitochondrial pathways; mitochondrial transmembrane resistance ({Delta}{Psi}m) was altered and modulation of mitochondrion-mediated apoptosis regulating genes changed (increased transcriptional Bax, cytochrome-c and Apaf-1 and downregulated Bcl-2), whereas caspase-9 and -3 expression increased. Apoptotic effects by P. zopfii GT-II were more pronounced in macrophages compared to MECs. In a murine mammary infection model, P. zopfii GT-II replicated in the mammary gland and caused severe inflammation with infiltration of macrophages and neutrophils and upregulation of pro-inflammatory genes (TNF-, IL-1{beta} and Cxcl-1) and also apoptosis of epithelial cells. Thus, we concluded P. zopfii GT-II is a mastitis-causing pathogen that triggers severe inflammation and also mitochondrial apoptosis. Author summaryBovine mastitis (inflammation of the udder) reduces milk production and quality, causing huge economic losses in the dairy industry worldwide. Although the alga Prototheca zopfii is a major cause of mastitis in dairy cows, mechanisms by which it damages mammary tissues are not well known. Here, we used cell cultures and a mouse model of mastitis to determine how Prototheca caused inflammation and cell death in mammary tissues. Prototheca invaded mammary gland cells, from cattle and mice, as well as macrophages (white cells that take up and kill pathogens) and caused cell death by interfering with mitochondria. Furthermore, Prototheca causes severe inflammation and tissue damage when injected into the mammary glands of mice. Although there are two genotypes of P. zopfii, only genotype II causes tissue damage, whereas gentotype I, common in farm environments, does not damage mammary tissues. Since P. zopfii is an alga and not a bacterium, antibiotic treatments, frequently used to treat mastitis in cattle, are not effective against this organism. Understanding how P. zopfii damages mammary tissue and causes mastitis is important new knowledge to promote future development of evidence-based approaches to prevent and treat mammary gland infections with this organism.

microbiology↗