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Title: Phase Variation of PorA, a Major Outer Membrane Protein, Mediates Escape of Bactericidal Antibodies by Neisseria meningitides
Authors: Tauseef, Isfahan
Ali, Youssif M.
Bayliss, Christopher D.
First Published: 12-Feb-2013
Publisher: American Society for Microbiology
Citation: Infection and Immunity, 2013, 81 (4), pp. 1374–1380
Abstract: Several outer membrane proteins of Neisseria meningitidis are subject to phase variation due to alterations in simple sequence repeat tracts. The PorA protein is a major outer membrane protein and a target for protective host immune responses. Phase variation of PorA is mediated by a poly-G repeat tract present within the promoter, leading to alterations in protein expression levels. N. meningitidis strain 8047 was subjected to serial passage in the presence of P1.2, a PorA-specific bactericidal monoclonal antibody. Rapid development of resistance to bactericidal activity was associated with a switch in the PorA repeat tract from 11G to 10G. Phase variants with a 10G repeat tract exhibited a 2-fold reduction in surface expression of PorA protein. A mutS mutant of strain 8047, with an elevated phase variation rate, exhibited a higher rate of escape and an association of escape with 10G and 9G variants, the latter having a 13-fold reduction in surface expression of PorA. We conclude that graduated reductions in the surface expression of outer membrane proteins mediated by phase variation enable meningococci to escape killing in vitro by bactericidal antibodies. These findings indicate how phase variation could have a major impact on immune escape and host persistence of meningococci.
DOI Link: 10.1128/IAI.01358-12
ISSN: 0019-9567
eISSN: 1098-5522
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2013 Tauseef et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 Unported license (
Appears in Collections:Published Articles, Dept. of Genetics

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