1State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, No. 155, Changbai Road, Changping, Beijing, 102206 China.
Published: July 2019
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Article Abstract
Background: Hemolysis of bacteria is an important phenotype used for typing and characterizing strains with specific biomarkers and even a virulence factor in bacterial pathogenesis. In , hemolysin HlyA is responsible for hemolysis of sheep red blood cells, and this hemolytic phenotype is used as a biotyping indicator and considered one of the virulence factors. At the beginning of the seventh cholera pandemic, the El Tor biotype strains of serogroup O1 were distinguished by hemolysis from the sixth pandemic O1 classical biotype strains, whereas during the following epidemics, nonhemolytic El Tor strains appeared, suggesting phenotypic and genetic variations in these strains. This study aimed to investigate the possible mechanisms involved in nonhemolysis of El Tor strains.
Results: Five sequence types of genes were found in the studied O1 El Tor strains isolated during the seventh pandemic. A 4-base deletion in caused the HlyA protein mutation and non-hemolytic phenotype. Some strains carry wildtype genes but are still non-hemolytic, and greatly reduced transcription and blocked secretion of hemolysin were observed in hemolysis tests of the subcellular components and transcription/expression analysis of .
Conclusions: Mechanisms responsible for nonhemolysis of the epidemic O1 El Tor strains are complex and not only confined to gene mutation but also deficiencies of transcription and extracellular transport of HlyA. Mutations in gene regulation and protein secretion systems of HlyA in the nonhemolytic strains should be areas of concern in future studies.
Toxin-producing strains are the etiological agents of the severe upper respiratory disease, diphtheria. A global phylogenetic analysis revealed that biotype gravis is particularly lethal as it produces diphtheria toxin and a range of other virulence factors, particularly when it encounters low levels of iron at sites of infection. To gain insight into how it colonizes its host, we have identified iron-dependent changes in the exoproteome and surfaceome of strain 1737 using a combination of whole-cell fractionation, intact cell surface proteolysis, and quantitative proteomics.
Introduction (PA) is a bacterial species commonly isolated from human clinical specimens. Despite being present in the environment as a saprophyte, PA possesses the ability to cause human infections, especially among debilitated patients. It is therefore essential to understand the genomic imprints of antimicrobial resistance (AMR) and virulence genes associated with PA isolated from patient samples.
yeasts play a relevant role in the fermentation industry, showing controversial behavior. There is growing interest in these yeasts in the fermentation industry as beer and bioethanol production, while in winemaking, they are considered spoilage microorganisms mainly used to produce ethyl phenols. These compounds may alter wine's organoleptic characteristics, leading to significant economic loss.
Usutu virus (USUV) is an emerging zoonotic virus transmitted primarily by mosquitoes. Since its introduction into Europe from Africa during the late 20th century, it has caused mortality within populations of passerine birds and captive owls, and can on occasion lead to disease in humans. USUV was first detected in the UK in 2020 and has become endemic, having been detected in either birds and/or mosquitoes every subsequent year.
Department of Molecular Biology and Microbiology, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USA.
Bacteria and their predatory viruses (bacteriophages or phages) are in a perpetual molecular arms race. This has led to the evolution of numerous phage defensive systems in bacteria that are still being discovered, as well as numerous ways of interference or circumvention on the part of phages. Here, we identify a unique molecular battle between the classical biotype of and virulent phages ICP1, ICP2, and ICP3.
