Interestingly, for 3 of these families, the number and insertion site of the IS elements present in AP200 differ from those present in the other two serotype 11A, ST62 strains, SP11-BS70 [GenBank: NZ_ABAC00000000] and MLV-016 [GenBank: NZ_ABGH00000000], although the draft genome status of these two strains makes it impossible to carry out a complete comparison. Only 3 out of 8 IS1515 insertions, and only 2 out of 4 of the IS1380-ISSpn5 insertions are shared between AP200 and the other serotype 11A strains, while one of the IS1239 copies is present in AP200 only and is integrated
in the comC gene, making AP200 unable to develop natural competence. The fact that the insertion sites for IS1239, IS1380, and IS1515 copies vary between ST62 strains suggests that these IS elements maintained their ability to transpose click here within the strains. In AP200, selleck compound one copy of IS1515 is inserted within
the nanB gene, producing a truncated Neuraminidase B. In addition to these known IS elements, other 7 non characterized elements are present in AP200 in a number of copy ranging from 1 to 3. These ISs have been named from ISSpn_AP200_1 to ISSpn_AP200_7. Notably, AP200 shares with the other serotype 11A ST62 strains, an unique mutation in the 23S rRNA (T552C) that is not present in the other sequenced pneumococci. This mutation has also been confirmed by Sanger sequencing. Virulence factors A plethora of virulence factors have been described in S. pneumoniae [30]. Among them, the most important is the polysaccharide capsule, shielding pneumococci from
the host natural immune defense. The capsular serotype of AP200 was identified as 11A according to the Quellung reaction [31], but sequence analysis revealed that the capsular locus matched closely that of serotype 11D. In particular, AP200 showed only 3 nucleotide changes when compared to the 11D capsular locus of the reference strain 70/86 [GenBank: CR931656] [7]: two silent transitions in wze and wchA, respectively, and a G/A transition (G10118A) determining a change of a serine into an asparagine in the AG-881 cell line glycosyl transferase gene wcrL. Also the capsular locus of the two other ST62 serotype 11A strains, SP11-BS70 these [21] and MLV-016 [GenBank: NZ_ABGH00000000], match with the 11D capsular locus. SP11-BS70, like AP200, has been repeatedly tested using the Quellung reaction by us and by the pneumococcal reference laboratory at the Statens Serum Institute, yielding consistently serotype 11A. From these results it appears that these ST62 isolates have a serotype 11A phenotype, but possess an 11D capsular locus. The same conclusion has been reached by Moon Nahm’s laboratory examining the serotype 11A isolates obtained at the Centers for Disease Control and Prevention in Atlanta, GA (M.