Lipooligosaccharide biosynthesis genes of nontypable Haemophilus influenzae 2019

LPS/LOS, the compound found only in gram-negative bacterial outer membrane, plays important roles in bacterial maintenance as well as its pathogenesis. We isolated and characterized several genes required for NTHi 2019 LOS biosynthesis, which encode enzymes required for sugar substrate synthesis or the transfer of substrates to receptor molecules. The htrB gene, however, appears to have more complex role. It has acryltransferase activity as well as various other activity, which may control regulation of LOS biosynthesis as well as its pathogenicity. Evidences supporting the latter come from the observations that the lipid A of the B29 induced significantly less TNF ${\alpha}$ from macrophages than that of the wild type LOS (unpublished data). H. influenzae A2-htrB mutant strain was also significantly less invasive than the wild type strain. The structural similarities of the enterobacterial LPS and the Haemophilus LOS enabled us to isolate the NTHi 2019 genes involved in LOS biosynthesis genes by using the S. typhimurium LPS deep core mutants. While a similar approach has been used for E. coli, this technique for selection of an LPS phenotype has not been applied to nonenterobacterial species. The difficulties inherent in the molecular manipulation of organism such as Neisseria and Haemophilus species make this approach particularly attractive in the identification and cloning LOS genes. Studies on genetic features of LPS/LOS biosynthesis would be useful for understanding bacterial pathogenesis as well as for developing vaccines for these gram-negative pathogenic bacteria.