Endotoxins are responsible for initiation of septic shock which increases the number of fatalities in Gram-negative bacteremia among hospital patients. The morality from septic shock is still high despite recent developments in antibiotic therapy because antibiotics are unable to decrease the level of free lipopolysaccharide in the blood stream. Another approach to the treatment and prevention of septicaemia involves stimulation of an immune response against LPS. It was found that immunization with the core structures of endotoxin conjugated with proteins protected animals against infections and endotoxic shock. Anticonjugate sera are of great interest because they are directed against conserved parts of LPS and therefore could have cross-reactive and cross-protective properties with respect to many Gram-negative rods.
Most Proteus lipopolysaccharides (LPSs) contain uronic acids or their amides with different amino acids, which together with other negatively charged components account for the acidic character of such LPS molecules. Previous studies have shown the significance of an amide of galacturonic acid with lysine [D-GalA(L-Lys)] for serological specificity of O-antigens from few P. mirabilis strains. In this work, the immunodominant role of GalALys was indicated for the P. penneri 42 LPS core region. The studies also showed the serological identity of core oligosaccharides from P. penneri 42 (O71), P. mirabilis 51/57 (O28) and R14/S1959 strains.
Our previous study showed the efficacy of lactoferrin-monophosphoryl lipid A isolated from Hafnia alvei LPS complex (LF-MPL H.a.) as an adjuvant in stimulation of humoral and cellular immune response in mice to conventional antigens and a lower pyrogenicity of the complex as compared with MPL H.a. alone. In the present investigation we demonstrated that LF-MPL H.a. complex enhanced the immunity of BALB/c mice immunized with Plesiomonas shigelloides CNCTC 138/92 bacterial vaccine, against P. shigelloides infection. The adjuvant effect was evidenced by a significant increase of the antigen-specific serum IgG, IgG2a, and IgG1 and elevation of antigen-specific serum IgA concentrations. In addition, application of the adjuvant facilitated better clearance of the bacteria in spleens and livers of infected mice when compared with MPL H.a. alone. These features of the new adjuvant may predispose it for vaccination protocols in humans.
The aim of the studies was the use of Haemophilus somnus vaccine in the immunization of chickens to protect them against Salmonella infections by increasing the local cross-immunity of the alimentary tract. Broilers were immunized with a live vaccine administered in drinking water on the 1st and the 14,h day of life. The groups were as follows: H. somnus (24h broth culture, 109 cfu/ml); Salmonella typhimurium (live, attenuated vaccine, 1010 cfu/ml, TAD, Cuxhaven, FRG), and the control. The efficacy of the vaccines applied was assessed upon: bacteriological monitoring of gut and organs for the presence of Salmonella, results of challenge with S. enteritidis on the 10th day, following the second vaccination, and serological monitoring (specific antibodies -IgA, IgG and IgM in bile, serum and intestinal mucus by ELISA test). The results tndftate that the chickens' immunization with H. somnus oral vaccine protect them from infection with the virulent strain of S. enteritidis. On the 18lh day after the challenge no S. enteritidis was found in the cloaca and organs of the chickens immunized with H. somnus and S. typhimurium, whereas in the control group. S. enteritidis was isolated in 20 to 50% of the samples collected from the duodenum, liver and caecum. The serological examination showed that in immunized chickens, after the challenge a rapid, anamnestic response of IgA specific antibodies occurred in all the fluids examined (serum, bile and intestinal mucus). It indicates the protective role of local cross-reacting antibodies, induced by oral H.somnus vaccination.
The rough mutants of Gram-negative bacteria are widely used to induce protective antisera but the nature of the target epitope for such antibodies is not precisely defined. Endotoxin is one of several antigens present on the surface of bacterial cells, which are able to elicit specific antibodies. We studied the specificity of antibodies produced against a conjugate of E. coli J5 endotoxin core oligosaccharide with tetanus toxoid. The use of chemically defined antigen for immunisation excludes the possibility of production of antibodies against other cell surface antigens. A comparison of this monospecific anti-endotoxin serum with antiserum against E. coli J5 whole cells was performed in order to distinguish the role that endotoxin core oligosaccharide plays in the interaction with humoral host defences from that of other potentially important Gram-negative bacterial surface antigens. The reactivity of both sera with smooth and rough lipopolysaccharides was determined in ELISA, immunoblotting and by flow cytometry. Both antisera reacted with similar specificity with most lipopolysaccharides of identical or related core type. Less distinct reactions with endotoxins of the antibacterial serum in comparison with the anti-conjugate serum were found in all serological tests. LPS of E. coli O100 that showed the strongest reactions with both sera was used to stimulate IL-6, TNFα and nitric oxide production by the J-774A.1 cell line. Both sera were used to inhibit that stimulation and no inhibitory effects of the examined sera in comparison with non-immune serum were observed.
The structures and serological activities of core oligosaccharide of Hafnia alvei strains have been investigated. Methylation analysis, NMR spectroscopy and various specific degradation procedures were the principal methods used. It is concluded that, core hexasaccharides are identical in the lipopolysaccharides tested and are built of two glucose, three heptose and one 2-keto-3-deoxyoctulosonic acid residues. The antiserum raised against the ATCC13337oligosaccharide core-tetanus toxoid conjugate cross-reacted strongly with all lipopolysaccharides used as antigens in ELISA test, suggesting that this core region is the common structure in the Hafnia genus.