Lineage-specifi c Virulence Determinants of Haemophilus infl uenzae Biogroup aegyptius

An emergent clone of Haemophilus infl uenzae biogroup aegyptius (Hae) is responsible for outbreaks of Brazilian purpuric fever (BPF). First recorded in Brazil in 1984, the so-called BPF clone of Hae caused a fulminant disease that started with conjunctivitis but developed into septicemic shock; mortality rates were as high as 70%. To identify virulence determinants, we conducted a pangenomic analysis. Sequencing of the genomes of the BPF clone strain F3031 and a noninvasive conjunctivitis strain, F3047, and comparison of these sequences with 5 other complete H. infl uenzae genomes showed that >77% of the F3031 genome is shared among all H. infl uenzae strains. Delineation of the Hae accessory genome enabled characterization of 163 predicted protein-coding genes; identifi ed differences in established autotransporter adhesins; and revealed a suite of novel adhesins unique to Hae, including novel trimeric autotransporter adhesins and 4 new fi mbrial operons. These novel adhesins might play a critical role in host–pathogen interactions.