Peptidoglycan-Free Bacterial Ghosts Confer Enhanced Protection against Infection.

To develop a modern plague vaccine, we used hypo-endotoxic   bacterial ghosts (BGs) with combinations of genes encoding the bacteriophage ɸX174 lysis-mediating protein E and/or holin-endolysin systems from λ or L-413C phages. Expression of the protein E gene resulted in the BGs that retained the shape of the original bacterium. Co-expression of this gene with genes coding for holin-endolysin system of the phage L-413C caused formation of structures resembling collapsed sacs.

The subcutaneous inoculation of pH 6 antigen mutants of Yersinia pestis does not affect virulence and immune response in mice.

Two isogenic sets of Yersinia pestis strains were generated, composed of wild-type strains 231 and I-1996, their non-polar pH 6(-) mutants with deletions in the psaA gene that codes for its structural subunit or the whole operon, as well as strains with restored ability for temperature- and pH-dependent synthesis of adhesion pili or constitutive production of pH 6 antigen. The mutants were generated by site-directed mutagenesis of the psa operon and subsequent complementation in trans. It was shown that the loss of synthesis or constitutive production of pH 6 antigen did not influence Y.

Relationship of the lipopolysaccharide structure of Yersinia pestis to resistance to antimicrobial factors.

Disruption of lipopolysaccharide (LPS) biosynthesis genes in an epidemiologically significant Yersinia pestis strain showed that the ability to synthesize the full inner core of the LPS is crucial for resistances to the bactericidal action of antimicrobial peptides and to complement-mediated serum killing. Resistance to polymyxin B also requires a high content of the cationic sugar, 4-amino-4-deoxy-L-arabinose, in lipid A.

Effect of deletion of the lpxM gene on virulence and vaccine potential of Yersinia pestis in mice.

Yersinia pestis undergoes an obligate flea-rodent-flea enzootic life cycle. The rapidly fatal properties of Y. pestis are responsible for the organism's sustained survival in natural plague foci.

Intraspecies and temperature-dependent variations in susceptibility of Yersinia pestis to the bactericidal action of serum and to polymyxin B.

Lipopolysaccharide (LPS) structure impacts the bactericidal action of cationic peptides, such as polymyxin B (PMB), and sensitivity to killing by normal human serum (NHS). Cultivation of different subspecies strains of Yersinia pestis isolated from unrelated geographic origins at various temperatures (mammals, 37 degrees C; fleas, 25 degrees C; or winter hibernation, 6 degrees C) affects LPS composition and structure. We tested the susceptibilities of various strains of Y.

Temperature-dependent variations and intraspecies diversity of the structure of the lipopolysaccharide of Yersinia pestis.

Yersinia pestis spread throughout the Americas in the early 20th century, and it occurs predominantly as a single clone within this part of the world. However, within Eurasia and parts of Africa there is significant diversity among Y. pestis strains, which can be classified into different biovars (bv.