Identifying candidate genetic determinants associated with invasion in pneumococcal lineages

After adjusting for serotype and country, GPSC1 and GPSC21 ranked fifth and 149th of 150 pneumococcal lineages, with invasion odds multipliers of 1.51 and 0.61, respectively.

• Why it matters: Serotype invasiveness estimates are confounded by strong serotype–lineage association, so independent lineage determinants are needed to flag unexpectedly invasive lineages and guide mechanism studies.
• What they did: Using temporally matched carriage and invasive isolates from children aged <7 years in South Africa and the USA, the authors fit a logistic mixed-effects model (GPSC random effect; serotype and country fixed effects) and ran a species-wide GWAS of invasion.
• The result: From 1,569 invasion-associated unitigs, 272 differentiated GPSC1 from GPSC21, with the strongest signal mapping to hk11 (desK) and bgaA highest among known antibody-binding targets, plus extra ClpX variants in GPSC1 CC271 versus CC420.