Haemophilus parainfluenzae expresses diverse lipopolysaccharide O-antigens using ABC transporter and Wzy polymerase-dependent mechanisms

Abstract

Lipopolysaccharide O-antigens are the basis of serotyping schemes for Gram negative bacteria and help to determine the nature of host–bacterial interactions. Haemophilus parainfluenzae is a normal commensal of humans but is also an occasional pathogen. The prevalence, diversity and biosynthesis of O-antigens were investigated in this species for the first time. 18/18 commensal H. parainfluenzae isolates contain a O-antigen biosynthesis gene cluster flanked by glnA and pepB, the same position as the hmg locus for tetrasaccharide biosynthesis in Haemophilus influenzae. The O-antigen loci show diverse restriction digest patterns but fall into two main groups: (1) those encoding enzymes for the synthesis and transfer of FucNAc4N in addition to the Wzy-dependent mechanism of O-antigen synthesis and transport and (2) those encoding galactofuranose synthesis/transfer enzymes and an ABC transporter. The other glycosyltransferase genes differ between isolates. Three H. parainfluenzae isolates fell outside these groups and are predicted to synthesise O-antigens containing ribitol phosphate or deoxytalose. Isolates using the ABC transporter system encode a putative O-antigen ligase, required for the synthesis of O-antigen-containing LPS glycoforms, at a separate genomic location. The presence of an O-antigen contributes significantly to H. parainfluenzae resistance to the killing effect of human serum in vitro. The discovery of O-antigens in H. parainfluenzae is striking, as its close relative H. influenzae lacks this cell surface component.

Genome Structure of the Opportunistic Pathogen Paracoccus yeei (Alphaproteobacteria) and Identification of Putative Virulence Factors

“…In addition, putative sugar transferases, which exhibit moderate similarity (ca. 50%) to undecaprenyl-phosphate galactose phosphotransferases of Haemophilus spp., are probably involved in lipopolysaccharide biosynthesis ( Young et al, 2013 ).…”

Microbiological characteristics of different tongue coatings in adults

“…This bacterium is a gram-negative bacterium and is a normal inhabitant of the human respiratory tract. However it is associated with a variety of infectious diseases under certain conditions, such as infective endocarditis, pneumonia, otitis media and arthritis [46,47]. WGF is frequently observed in patients with acute cerebral infarction and is associated with fibrinogen levels [38].…”

Haemophilus parainfluenzae Strain ATCC 33392 Forms BiofilmsIn Vitroand during Experimental Otitis Media Infections

“…Gram-negative bacterium that normally resides within the human nasopharynx and periodontal spaces, where its carriage is usually without significant symptoms (19). This species is differentiated from the closely related Haemophilus influenzae by the lack of a strict requirement for hemin and differences in its surface glycolipid populations (20)(21)(22)(23). Notably, many of these surface factors lacking in H. parainfluenzae are those that we have previously shown to be important determinants of biofilm formation and maturation for H. influenzae (14,(24)(25)(26).…”