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Journal articles
Serum resistance and phase variation of a nasopharyngeal non-typeable Haemophilus influenzae isolate
Abstract : Haemophilus influenzae harbours a complex array of factors to resist human complement attack. As non-typeable H. influenzae (NTHi) strains do not possess a capsule, their serum resistance mainly depends on other mechanisms including LOS decoration. In this report, we describe the identification of a highly serum resistant, nasopharyngeal isolate (NTHi23) by screening a collection of 77 clinical isolates. For NTHi23, we defined the MLST sequence type 1133, which matches the profile of a previously published invasive NTHi isolate. A detailed genetic analysis revealed that NTHi23 shares several complement evading mechanisms with invasive disease isolates. These mechanisms include the functional expression of a retrograde phospholipid trafficking system and the presumable decoration of the LOS structure with sialic acid. By screening the NTHi23 population for spontaneous decreased serum resistance, we identified a clone, which was about 103-fold more sensitive to complement-mediated killing. Genome-wide analysis of this isolate revealed a phase variation in the N'-terminal region of lpsA, leading to a truncated version of the glycosyltransferase (LpsA). We further showed that a NTHi23 lpsA mutant exhibits a decreased invasion rate into human alveolar basal epithelial cells. Since only a small proportion of the NTHi23 population expressed the serum sensitive phenotype, resulting from lpsA phase-off, we conclude that the nasopharyngeal environment selected for a population expressing the intact and functional glycosyltransferase.
https://hal-pasteur.archives-ouvertes.fr/pasteur-03107776
Contributor : Reine Bouyssie Connect in order to contact the contributor
Submitted on : Tuesday, January 12, 2021 - 7:11:33 PM
Last modification on : Friday, January 7, 2022 - 3:47:54 AM
Long-term archiving on: : Tuesday, April 13, 2021 - 6:58:22 PM
Contributor : Reine Bouyssie Connect in order to contact the contributor
Submitted on : Tuesday, January 12, 2021 - 7:11:33 PM
Last modification on : Friday, January 7, 2022 - 3:47:54 AM
Long-term archiving on: : Tuesday, April 13, 2021 - 6:58:22 PM
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