Prevalence of genosubtypes (PorA types) of serogroup B invasive meningococcus in the north of Spain from 2000 to 2003

Meningococcal vaccines: current issues and future strategies

Since the introduction of the first meningococcal conjugate vaccines in 1999, remarkable progress has been made in reducing the morbidity and mortality caused by meningococcal disease. Currently, varying meningococcal conjugate vaccines provide protection against serogroups A, C, Y, and W meningococcal disease. A large impact has been seen after vaccine introduction, particularly in the UK after vaccinating all 1-17 year olds. The introduction of serogroup A conjugate vaccine in the meningitis belt has the potential to control epidemics of disease that disproportionately affect this area of the world. Issues remain that require continued vigilance with disease surveillance and frequent reassessment of vaccine strategies. These issues include duration of protection, potential increases in non-vaccine serogroups, and vaccine safety and potential interference with other routine vaccines. Serogroup B meningococcal vaccines are protein-based vaccines, with the first approved in early 2013. Understanding the potential impact of serogroup B vaccines is critical to developing future meningococcal vaccination strategies.

Clonal analysis of Neisseria meningitidis serogroup B strains in South Africa, 2002 to 2006: emergence of new clone ST-4240/6688

From August 1999 through July 2002, hyperinvasive Neisseria meningitidis serogroup B (MenB) clonal complexes (CCs), namely, ST-32/ET-5 (CC32) and ST-41/44/lineage 3 (CC41/44), were predominant in the Western Cape Province of South Africa. This study analyzed MenB invasive isolates from a national laboratory-based surveillance system that were collected from January 2002 through December 2006. Isolates were characterized by pulsed-field gel electrophoresis (PFGE) (n = 302), and multilocus sequence typing (MLST) and PorA and FetA typing were performed on randomly selected isolates (34/302, 11%). In total, 2,400 cases were reported, with the highest numbers from Gauteng Province (1,307/2,400, 54%) and Western Cape Province (393/2,400, 16%); 67% (1,617/2,400) had viable isolates and 19% (307/1,617) were identified as serogroup B. MenB incidence remained stable over time (P = 0.77) (average incidence, 0.13/100,000 population [range, 0.10 to 0.16/100,000 population]). PFGE (302/307, 98%) divided isolates (206/302, 68%) into 13 clusters and 96 outliers. The largest cluster, B1, accounted for 25% of isolates (76/302) over the study period; its prevalence decreased from 43% (20/47) in 2002 to 13% (8/62) in 2006 (P < 0.001), and it was common in the Western Cape (58/76, 76%). Clusters B2 and B3 accounted for 10% (31/302) and 6% (19/302), respectively, and showed no significant change over time and were predominant in Gauteng. Randomly selected isolates from clusters B1, B2, and B3 belonged to CC32, CC41/44, and the new CC4240/6688, respectively. Overall, 15 PorA and 12 FetA types were identified. MenB isolates were mostly diverse with no single dominant clone; however, CC32 and CC41/44 accounted for 35% and the new CC4240/6688 was the third most prevalent clone.

Influence of two vaccination campaigns on genetic diversity of invasive Neisseria meningitidis isolates in northern Spain (1997-2008)

Background

Neisseria meningitidis diversifies rapidly, due to its high recombination rates. The aim of this study was to analyze the possible impact of two vaccination campaigns (a once-off A/C polysaccharide vaccination campaign in people aged 18 months to 20 years old in 1997, and a meningococcal C conjugate vaccination campaign in children aged ≤6 years old from 2000 to 2008) on diversification of the population of invasive isolates obtained between 1997 and 2008. All of the 461 available isolates were included (2, 319, 123, 11 and 6 belonging to serogroups A, B, C, Y and W-135, respectively).

Methodology/Principal Findings

The isolates were analyzed for diversity using multilocus sequence typing, eBURST and the S.T.A.R.T.2 program. One hundred and seven sequence types (ST) and 20 clonal complexes were obtained. Five different STs (ST11, ST8, ST33, ST1163 and ST3496) included 56.4% of the isolates. With the exception of ST11, all other STs were associated with a specific serogroup. Epidemic circulation of serogroup C ST8 isolates was detected in 1997–1998, as well as epidemic circulation of ST11 isolates (serogroups B and C) in 2002–2004. The epidemic behavior of serogroup B ST11 (ST11_B:2a:P1.5) was similar, although with lesser intensity, to that of ST11 of serogroup C. Although clonality increased during epidemic years, the overall diversity of the meningococcal population did not increase throughout the 12 years of the study.

Conclusion

The overall diversity of the meningococcal population, measured by the frequency of STs and clonal complexes, numbers of alleles, polymorphic sites, and index of association, remained relatively constant throughout the study period, contradicting previous findings by other researchers.

PorA types in Neisseria meningitidis serogroup B isolated in Argentina from 2001 to 2003: implications for the design of an outer membrane protein-based vaccine

Identification ofNeisseria meningitidisPorA types remains important, as the PorA protein is a major immunogenic component of several meningococcal vaccines under development. In this study, 191N. meningitidisserogroup B isolates collected in Argentina through active laboratory-based surveillance from 2001 to 2003 were serosubtyped. Nucleotide sequences of theporAvariable region 1 (VR1) and VR2 regions were determined in 52 non-serosubtypeable isolates. A substantial number of distinct VR types were identified, and a new VR2 variant from the P1.16 family was described. This is the first report describing PorA types inN. meningitidisserogroup B isolates in Argentina. Furthermore, the wide diversity of subtypes detected by serosubtyping and genosubtyping reveals the difficulty in designing a useful outer-membrane vaccine applicable in this country. A possible mechanism responsible for altered PorA expression was analysed in two PorA types.

Neisseria meningitidis W-135 in the Basque Country, northern Spain

Neisseria meningitidis W-135 accounted for nine (1.6%) of 562 cases of invasive meningococcal disease and 17 (3.9%) of 430 meningococcal isolates from healthy carriers. There was no mortality associated with the invasive nine isolates, which belonged to subtype P1.6 and geno-subtype P1.18-1. All invasive isolates and 15 of the 17 isolates from healthy carriers belonged to sequence type 22 by multilocus sequence typing, and showed a similarity of > 85% by pulsed-field gel electrophoresis following digestion with NheI. These results demonstrate that W-135 isolates in the Basque region of northern Spain have a high degree of similarity and are almost clonal.