Helicobacter pylori Biofilm Confers Antibiotic Tolerance in Part via A Protein-Dependent Mechanism

Helicobacter pylori, a WHO class I carcinogen, is one of the most successful human pathogens colonizing the stomach of over 4.4 billion of the world’s population. Antibiotic therapy represents the best solution but poor response rates have hampered the elimination of H. pylori. A growing body of evidence suggests that H. pylori forms biofilms, but the role of this growth mode in infection remains elusive. Here, we demonstrate that H. pylori cells within a biofilm are tolerant to multiple antibiotics in a manner that depends partially on extracellular proteins. Biofilm-forming cells were tolerant to multiple antibiotics that target distinct pathways, including amoxicillin, clarithromycin, and tetracycline. Furthermore, this tolerance was significantly dampened following proteinase K treatment. These data suggest that H. pylori adapts its phenotype during biofilm growth resulting in decreased antibiotic susceptibility but this tolerance can be partially ameliorated by extracellular protease treatment.National Institute of Allergy and Infectious DiseasesNational Institutes of HealthPeer Reviewe

Sequence Diversity andAntibody Response to Autologous and Heterologous MSP2 Antigens in a Prospective Malaria Immunology Cohort

Malaria, caused by the Plasmodium parasite and transmitted by mosquitoes, kills almost half a million people each year. Drug resistance in both the parasite and its vector make preventative measures increasingly important, and a fully protective vaccine is absolutely necessary to eradicate the disease. However, genetic diversity of the parasite makes vaccine development difficult. One of the best vaccine candidates is MSP2, a surface protein present during the blood stage of P. falciparum infection. Antibodies, which are important for natural immunity, have been shown to bind MSP2 and prevent parasite infection of blood cells. The purpose of this study was to analyze MSP2 sequence diversity in a cohort of patients infected while traveling or living in sub-Saharan Africa, and to investigate patient antibody responses to MSP2 variants infecting other individuals. Parasite isolates from our cohort were made up of 47% 3D7 alleles and 53% FC27 alleles. Protein sequences showed similar levels of conservation within allelic families, and blocks of conserved amino acids between different variants suggest there may be epitopes that can induce antibody production targeting multiple variants. Antibody reactivity tests suggest the variable region of MSP2 is important for antibody binding to variants of the same allelic type, while the conserved region is important for reactivity to different allelic types. This thesis gives evidence to the importance of including epitopes from conserved and variable regions of both MSP2 allelic families in order to induce strain-transcending immunity against P. falciparum malaria. A genomic surveillance platform for indel-rich genes from Plasmodium spp. using long-read amplicon sequencin

Helicobacter pylori Biofilm Involves a Multigene Stress-Biased Response, Including a Structural Role for Flagella

Biofilms, communities of bacteria that are embedded in a hydrated matrix of extracellular polymeric substances, pose a substantial health risk and are key contributors to many chronic and recurrent infections. Chronicity and recalcitrant infections are also common features associated with the ulcer-causing human pathogen H. pylori. However, relatively little is known about the role of biofilms in H. pylori pathogenesis, as well as the biofilm structure itself and the genes associated with this mode of growth. In the present study, we found that H. pylori biofilm cells highly expressed genes related to cell envelope and stress response, as well as those encoding the flagellar apparatus. Flagellar filaments were seen in high abundance in the biofilm. Flagella are known to play a role in initial biofilm formation, but typically are downregulated after that state. H. pylori instead appears to have coopted these structures for nonmotility roles, including a role building a robust biofilm.Helicobacter pylori has an impressive ability to persist chronically in the human stomach. Similar characteristics are associated with biofilm formation in other bacteria. The H. pylori biofilm process, however, is poorly understood. To gain insight into this mode of growth, we carried out comparative transcriptomic analysis between H. pylori biofilm and planktonic cells, using the mouse-colonizing strain SS1. Optimal biofilm formation was obtained with a low concentration of serum and 3 days of growth, conditions that caused both biofilm and planktonic cells to be ∼80% coccoid. Transcriptome sequencing (RNA-seq) analysis found that 8.18% of genes were differentially expressed between biofilm and planktonic cell transcriptomes. Biofilm-downregulated genes included those involved in metabolism and translation, suggesting these cells have low metabolic activity. Biofilm-upregulated genes included those whose products were predicted to be at the cell envelope, involved in regulating a stress response, and surprisingly, genes related to formation of the flagellar apparatus. Scanning electron microscopy visualized flagella that appeared to be a component of the biofilm matrix, supported by the observation that an aflagellated mutant displayed a less robust biofilm with no apparent filaments. We observed flagella in the biofilm matrix of additional H. pylori strains, supporting that flagellar use is widespread. Our data thus support a model in which H. pylori biofilm involves a multigene stress-biased response and that flagella play an important role in H. pylori biofilm formation

Helicobacter pylori Biofilm Confers Antibiotic Tolerance in Part via A Protein-Dependent Mechanism.

Helicobacter pylori, a WHO class I carcinogen, is one of the most successful human pathogens colonizing the stomach of over 4.4 billion of the world's population. Antibiotic therapy represents the best solution but poor response rates have hampered the elimination of H. pylori. A growing body of evidence suggests that H. pylori forms biofilms, but the role of this growth mode in infection remains elusive. Here, we demonstrate that H. pylori cells within a biofilm are tolerant to multiple antibiotics in a manner that depends partially on extracellular proteins. Biofilm-forming cells were tolerant to multiple antibiotics that target distinct pathways, including amoxicillin, clarithromycin, and tetracycline. Furthermore, this tolerance was significantly dampened following proteinase K treatment. These data suggest that H. pylori adapts its phenotype during biofilm growth resulting in decreased antibiotic susceptibility but this tolerance can be partially ameliorated by extracellular protease treatment