Whole-Genome Sequencing-Based Characterization of a Listeria monocytogenes Strain from an Aborted Water Buffalo in Southern Italy

Listeria monocytogenes is a Gram-positive pathogen causing life-threatening infections both in humans and animals. In livestock farms, it can persist for a long time and primarily causes uterine infections and encephalitis in farmed animals. Whole genome sequencing (WGS) is currently becoming the best method for molecular typing of this pathogen due to its high discriminatory power and efficiency of characterization. This study describes the WGS-based characterization of an L. monocytogenes strain from an aborted water buffalo fetus in southern Italy. The strain under study was classified as molecular serogroup IVb, phylogenetic lineage I, MLST sequence type 6, Clonal Complex 6, and cgMLST type CT3331, sublineage 6. Molecular analysis indicated the presence of 61 virulence genes and 4 antibiotic resistance genes. Phylogenetic analysis, including all the publicly available European L. monocytogenes serogroup IVb isolates, indicated that our strain clusterized with all the other CC6 strains and that different CCs were variably distributed within countries and isolation sources. This study contributes to the current understanding of the genetic diversity of L. monocytogenes from animal sources and highlights how the WGS strategy can provide insights into the pathogenic potential of this microorganism, acting as an important tool for epidemiological studies

Human cardiac mesoangioblasts isolated from hypertrophic cardiomyopathies are greatly reduced in proliferation and differentiation potency

AIMS: Our objective was to test whether progenitor cell proliferation and differentiation potential may vary depending upon the disease of the donor. METHODS AND RESULTS: Human cardiac mesoangioblasts were isolated from cardiac muscle biopsies of patients undergoing open heart surgery for correction of mitral regurgitation following an acute myocardial infarction (MR-MI) or correction of mitral and aortic regurgitation with ensuing left ventricular hypertrophy (MAR-LVH). The cells express surface markers and cardiac genes similar to mouse cardiac mesoangioblasts; they have limited self-renewing and clonogenic activity and are committed mainly to cardiogenesis. Although cardiac differentiation can be induced by 5-azacytidine or by co-culture with rat neonatal cardiomyocytes, human cells do not contract spontaneously like their mouse counterparts. When locally injected in the infarcted myocardium of immunodeficient mice, cardiac mesoangioblasts generate a chimeric heart that contains human myocytes and some capillaries; likewise, they colonize chick embryo hearts when transplanted in ovo. At variance with cells from patients with MR-MI, when isolation was performed on biopsies from MAR-LVH, cells could be isolated in much lower numbers, proliferated less extensively and failed to differentiate. CONCLUSION: Cardiac mesoangioblasts are present in the human heart but this endogenous progenitor population is progressively exhausted, possibly by continuous and inefficient regeneration attempts