Neisseria meningitidis (SD1C) when grown in an iron-limited medium at low pH exhibited a dramatic increase in virulence for the mouse. This enhanced virulence correlated with a specific colonial type, and altered outer membrane protein profile, the expression of an uptake sytem for iron from human transferrin, and an increased resistance to phagocytosis by mouse polymorphonuclear leukocytes. The outer membrane of cells grown at pH 6.6 contained a 69,000 molecular weight protein (protein III) that was exposed on the cell surface. The outer membrane of iron-limited cells grown at pH 7.2 also exhibited protein III, but cells grown at pH 7.2 with sufficient iron possessed only minute quantities of this protein. Only iron-limited cells actively accumulated iron from human transferrin. Iron-limited cells initially took up ('59)Fe from transferrin at a similar rate, irrespective of their growth pH, but after 60 minutes cells grown at neutral pH accumulated less than half the ('59)Fe of cells from pH 6.6 cultures. At 24 hours, N. meningitidis (M2092) produced small and large colonies in which the cells elaborated predominantly thin (2.5 nm) and thick (4.5 nm) pili, respectively. The piliated meningococci possessed a sizeable intracellular pili(n) pool and, although in vitro pili reassembly was energy-independent, the in vivo assembly of pili on the meningococcal surface required a functional respiratory chain. Meningococci normally piliated at pH 7.2 were nonpiliated at pH 6.6, whereas nonpiliated meningococci at pH 7.2 remained nonpiliated at low pH. The effect of simulated in vivo growth conditions on meningococcal phenotype and virulence are discussed.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.68601 |
| Date | January 1981 |
| Creators | Brener, David. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Microbiology and Immunology) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000137534, proquestno: AAINK54749, Theses scanned by UMI/ProQuest. |
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