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Infection and Immunity, June 1999, p. 2928-2934, Vol. 67, No. 6
Department of Medical Microbiology and
Reference Laboratory for Bacterial Meningitis, Academic Medical
Center, University of Amsterdam, Amsterdam, The Netherlands
Received 19 January 1999/Returned for modification 25 February
1999/Accepted 2 April 1999
PorA is an important component in a vaccine against infection with
Neisseria meningitidis. However, porA-negative
meningococci were isolated from patients, thereby potentially limiting
the role of PorA-mediated immunity. To analyze the mechanism by which the porA deletion occurred, the regions upstream and
downstream of porA from three meningococcal strains
(H44/76, H355, and 860183) were sequenced. The porA
upstream region in strain 860183 contains a cluster of 22 repetitive palindromic RS3 core sequences
(ATTCCC-N8-GGGAAT) and 10 RS3 core sequences
(ATTCCC) in direct orientation. The cluster is flanked
by neisserial repeats, so-called Correia elements, and can be
subdivided into three repeats of 518 bp followed by a truncated repeat.
The porA upstream region of the other two strains showed
deletions, probably caused by a recombination between RS3 core
sequences. The porA downstream region of H44/76 and H355 contains the IS1106 element followed by a cluster of 10 palindromic RS3 core sequences, 4 RS3 core sequences, and 1 other RS3
core sequence (GGGAAT) and is followed by a Correia element.
This cluster can be subdivided into four direct repeats of 370 bp.
Strain 860183 had two such repeats instead of four. Sequence analysis
of the porA-negative variants indicated that the deletion
of porA occurred via a recombination between two copies of
the 116-bp region, containing two palindromic RS3 core
sequences and a single RS3 core sequence. This region is homologous in
the upstream and downstream clusters.
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Deletion of porA by Recombination between Clusters of
Repetitive Extragenic Palindromic Sequences in Neisseria
meningitidis
*
Corresponding author. Mailing address: Department of
Medical Microbiology, Academic Medical Center, University of Amsterdam, P.O. Box 22700, 1100 DE Amsterdam, The Netherlands. Phone:
31-20-5664862. Fax: 31-20-6979271. E-mail:
A.VANDERENDE{at}amc.uva.nl.
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