Bordetella pertussis is a strictly human pathogen colonizing the upper respiratory tract, causing a respiratory disease known as whooping cough or pertussis. The introduction of whole-cell vaccines and acellular vaccines, resulted in a significant reduction in the incidence of disease and reduce the fatalities associated with infection. However, epidemiological data show a significant increase in the incidence of the disease in recent decades. The increasing incidence is mainly attributed to the transition from the whole- cell vaccine to an acellular vaccine. Based on research from recent years has shown that acellular vaccines have many drawbacks, and it is therefore necessary to change the vaccination strategy. One possible solution to the situation is the development of a new generation of whole-cell vaccines with reduced reactogenicity. The new whole-cell vaccine was prepared by a genetically modified B. pertussis strain. B. pertussis was modified using allelic exchange to develop strain encoding enzymatically inactive pertussis toxin, modified lipid A and lacking dermonecrotic toxin. This combination of genetic modifications in mice led to a decrease in reactogenicity test vaccine in vivo. In case of intranasal infection whole-cell vaccine containing genetically modified strain is providing...

Bacterial pathogens assemble complex surface structures in an attempt to circumvent host immune detection. A great example is the glycolipid known as lipopolysaccharide or lipooligosaccharide (LPS), the major surface molecule in nearly all gram-negative organisms. LPS is anchored to the bacterial cell surface by a anionic hydrophobic lipid known as lipid A, the major agonist of the mammalian TLR4-MD2 receptor and likely target for cationic antimicrobial peptides (CAMPs) secreted by host cells (i.e. defensins). In this work we investigate LPS modification machinery in related ε-proteobacteria, Helicobacter pylori and Campylobacter jejuni, two important human pathogens, and demonstrate that enzymes involved in LPS modification not only play a role in evasion of host defenses but also an unexpected role in bacterial locomotion. More specifically, we identify the enzyme responsible for 4'-dephosphorylation of H. pylori lipid A, LpxF. Demonstrating that lipid A depohsphorylation at the 1 and 4'-positions by LpxE and LpxF, respectively, are the primary mechanisms used by H. pylori for CAMP resistance, contribute to attenuated TRL4-MD2 activation and are required for colonization of a the gastric mucosa in murine host. Similarly in C. jejuni, we identify an enzyme, EptC, responsible for modification of lipid A at both the 1 and 4'-positions with phosphoethanolamine (pEtN), also required for CAMP resistance in this organism. Suprisingly, EptC was found to serve a dual role in modifying not only lipid A with pEtN but also the flagellar rod protein FlgG at residue Thr75, required for motility and efficient flagella production. This work links membrane biogenesis with flagella assembly, both shown to be required for colonization of a host and adds to a growing list of post-translational modifications found in prokaryotes. Understanding how pathogens evade immune detection, interphase with the surrounding environment and assemble major surface features is key in the development of novel treatments and vaccines. / text