Abstract
Brazilian Purpuric Fever (BPF) is a hemorrhagic pediatric illness caused by Haemophilus influenzae biogroup aegyptius (Hae), a bacterium that was formerly associated with self-limited purulent conjunctivitis. BPF is assumed to be eradicated. However, the virulence mechanisms inherent to Hae strains associated with BPF is still a mystery and deficient in studies. Here, we aim to analyze the role of the autotransporter genes related to adherence and colonization las, tabA1, and hadA genes through RT-qPCR expression profiling and knockout mutants. Relative quantification by real-time PCR after infection in human cells and infant rat model suggests that las was initially downregulated probably duo to immune evasion, tabA1, and hadA were overexpressed in general, suggesting an active role of TabA1 and HadA1 adhesins in Hae in vitro and in vivo. Transformation attempts were unsuccessful despite the use of multiple technical approaches and in silico analysis revealed that Hae lacks genes related to competence in Haemophilus, which could be part of the elucidation of the difficulty of genetically manipulating Hae strains.
Highlights
Haemophilus influenzae biogroup aegyptius (Hae) was formerly associated with seasonal epidemics of self-limited purulent conjunctivitis (“pink eye”) until the 1980s, when an emergent clone of Hae was identified as the etiological agent of Brazilian Purpuric Fever (BPF) (Brenner et al, 1988; Harrison et al, 2008)
Animal-passaged isolation is described in Table 2; only Hae associated with BPF were recovered from the animal model
Rubin and Carlone (1989) had similar data in which Hae associated with BPF caused more expressive bacteremia when compared to non-BPF strains
Summary
Haemophilus influenzae biogroup aegyptius (Hae) was formerly associated with seasonal epidemics of self-limited purulent conjunctivitis (“pink eye”) until the 1980s, when an emergent clone of Hae was identified as the etiological agent of Brazilian Purpuric Fever (BPF) (Brenner et al, 1988; Harrison et al, 2008). BPF is a fulminant pediatric disease characterized by conjunctivitis, high fever, purpura, and sepsis. BPF major outbreaks arose from 1984 to 1990 in São Paulo, Brazil. Sporadic cases have been registered in Australia, USA (Harrison et al, 2008) and more recently in 2007 in Pará, Brazil (Santana-Porto et al, 2009). BPF is a disease with mandatory reporting in Brazil. The invasive unique phenotype highlights Hae associated with BPF (HaeBPF) from other Haemophilus influenzae strains (Hi)
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