Distribution of <i>mspA</i> and <i>nalP</i> in carriage (<i>n</i> = 127) and disease (<i>n</i> = 514) isolates.

<p>Distribution of <i>mspA</i> and <i>nalP</i> in carriage (<i>n</i> = 127) and disease (<i>n</i> = 514) isolates.</p

Distribution of phase ON and OFF <i>nalP</i> genes in carriage and disease isolates by serogroup.

a<p>No statistically significant difference in the frequency of the <i>nalP</i> phase ON phenotype between MenB and MenY carriage isolates (<i>p = </i>0.5547).</p>b<p>Statistically significant difference in the frequency of the <i>nalP</i> phase ON phenotype between MenB and MenY invasive isolates (<i>p<</i>0.0001).</p

Distribution of phase ON and OFF <i>mspA</i> genes in carriage and disease isolates by serogroup.

a<p>Statistically significant difference in the frequency of the <i>mspA</i> phase ON phenotype between MenB and MenY carriage isolates (<i>p<</i>0.0001).</p>b<p>Statistically significant difference in the frequency of the <i>mspA</i> phase ON phenotype between MenB and MenY invasive isolates (<i>p<</i>0.0001).</p>c<p>Includes 15 strains from ST-11 which harbor a mutation in <i>mspA</i> interrupting the gene. All 15 strains were phase OFF at the polyC tract.</p

Carriage isolates which lacked <i>nalP</i>.

a<p>Time points indicate when each strain was isolated from a particular carrier. Carriers were sampled in November and December 2008, and February and May 2009.</p>b, c<p>ND, not determined.</p

Variations in the size of the <i>nalP</i> deletion locus amongst <i>N. meningitidis</i> carriage isolates.

<p>The <i>nalP</i> deletion loci were amplified with primers specific for flanking genes. Amplicons were grouped into four classes based on size; representative samples are shown. Δ<i>nalP</i>1 (V128; Dec), Δ<i>nalP</i>2 (V130; Nov), Δ<i>nalP</i>3 (V199; Nov) and Δ<i>nalP</i>4 (V206; Dec).</p

Genetic arrangement of the <i>nalP</i> locus in <i>N. meningitidis</i> isolates.

<p>Unidirectional arrows represent ORFs. Repetitive elements are represented by different symbols. dRS3 consensus sequence: ATTCCCNNNNNNNNGGGAAT; REP4 consensus sequence: AAGACCGTCGGGCATCTGCAGCCGTC. Other repetitive sequences are not shown for clarity. Note that the figure is not drawn to scale but is a representation of the various repeat elements and genes present at the <i>nalP</i> locus in <i>N. meningitidis</i> MC58 and four <i>nalP</i>-negative carriage isolates representing Δ<i>nalP</i>1, Δ<i>nalP</i>2, Δ<i>nalP</i>3 and Δ<i>nalP</i>4 classes.</p

Immunoblot confirmation that <i>nalP</i> tract lengths of 7, 10 or 13Cs results in NalP expression.

<p>Secreted protein preparations from representative strains were probed with rabbit anti-NalP antisera to confirm that only <i>nalP</i> homopolymeric tract lengths of 7, 10 or 13Cs are consistent with the gene being in-frame and phase ON. Secreted NalP fragments ranged in size between <i>ca.</i> 68–70kDa due to sequence polymorphisms between alleles <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069746#pone.0069746-Turner2" target="_blank">[10]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069746#pone.0069746-vanUlsen2" target="_blank">[16]</a>. Strains used (tract length in parentheses): V199; May (7), V1114; Nov (8), V78; Nov (9), V131; Nov (10), V182; Nov (11), V169; Dec (12) and V193; Nov (13).</p

Distribution of tract lengths for <i>mspA</i> (A) and <i>nalP</i> (B) in invasive and carriage isolates.

<p>Invasive isolates shown are a sub-set of the 2010–11 UK isolates available in the Meningitis Research Foundation Meningococcus Genome Library database. Carriage isolates were from a study of meningococcal carriage in students at Nottingham University, UK during 2008–09. Black bars, carriage; grey bars, invasive. An ON PV state is produced by 6, 9 or 12Cs for <i>mspA</i> and by 7, 10 or 13Cs for <i>nalP</i>.</p

Phylogenetic breakdowns of both carriage and invasive strain collections showing the frequency of <i>nalP</i> deletions within clonal complexes.

a<p>(%) indicates the percentage of isolates within each clonal complex which were <i>nalP­</i>-negative.</p

Primers used in this study.

<p>Primers used in this study.</p