Inflammatory response of Haemophilus influenzae biotype aegyptius causing Brazilian Purpuric Fever

Abstract

The Brazilian Purpuric Fever (BPF) is a systemic disease with many clinical features of meningococcal sepsis and is usually preceded by purulent conjunctivitis. The illness is caused by Haemophilus influenza biogroup aegyptius, which was associated exclusively with conjunctivitis. In this work construction of the las gene, hypothetically responsible for this virulence, were fusioned with ermAM cassette in Neisseria meningitidis virulent strains and had its DNA transfer to non BPF H. influenzae strains. The effect of the las transfer was capable to increase the cytokines TNFα and IL10 expression in Hec-1B cells line infected with these transformed mutants (in eight log scale of folding change RNA expression). This is the first molecular study involving the las transfer to search an elucidation of the pathogenic factors by horizontal intergeneric transfer from meningococci to H. influenzae.

Analysis of potential virulence genes and competence to transformation in Haemophilus influenzae biotype aegyptius associated with Brazilian Purpuric Fever

“…The transcriptional fusion vector pLAN78 was used to evaluate the transformation capacity in Hae. pLAN78 was already successfully transferred to N. meningitidis and Hi strains ( Cury et al, 2014 ). Hae strains were again not competent to transformation whereas 19 and 4 CFU of Hi RdKW20 and Hi β-lac, respectively, were observed.…”

“…Our data showed that las was overexpressed in the Hae_BPF F3033 in the latter stages of the infection. In a previous study, our group showed that the transfer of las in NTHi strains caused a higher production of the tumor necrose factor alpha - TNF-α and interleukin 10 - IL10 in Hec1b versus the wildtype strains ( Cury et al , 2014 ). The las gene in Hae ( lav in non-BPF H. influenzae ) is evolutionarily related to the AT autB prone to phase variation in N. meningitidis ( Davis et al , 2001 ) .…”

“…Growth conditions and DNA extraction protocol followed the methods described previously ( Varela et al, 2014 ; Cury et al, 2014 ). Bacterial strains used in this work are described in Table 1 .…”

“…Transformation capacity of Hae F3031, F3033, KC1018, ATCCC11116 and established competent strains of Hi (Rd KW20 and β-lac) was compared using the protocol and the pLAN78 las::ermAM vector which contains the ATCC11116 las gene fused to the ermAM resistance cassette ( Cury et al , 2014 ).…”

Closed Complete Annotated Genome Sequences of Five Haemophilus influenzae Biogroup aegyptius Strains

“…It was hypothesized that acquisition and/or expression of particular virulence factors led to the emergence of BPF strains (3, 4), but the exact mechanism(s) behind the transition from causing conjunctivitis to causing severe invasive disease was never elucidated. However, a number of Haemophilus influenzae biogroup aegyptius -specific virulence factors have been identified and studied (5), such as lipooligosaccharide structure (1), extracellular proteins (6), and outer membrane proteins/adhesins (4, 7). Nevertheless, no factors were conclusively shown to be completely necessary for virulence (1), in part due to a lack of high-quality genome sequences.…”