Identification of a fibronectin-binding protein as adhesin of Streptococcus pyogenes

The role of streptococcal fibronectin-binding protein (Sfb protein) in the adherence of Streptococcus pyogenes to epithelial cells was analyzed by using a recombinant Sfb fusion protein which was constructed by fusion of the binding domain of Sfb protein to MS2 polymerase. Sfb fusion protein was overexpressed in Escherichia coli, purified from E. coli lysates by FPLC and analysed in binding experiments with 125I-labelled fibronectin and adherence studies with HEp2 epithelial cells. Lysates from E. coli expressing the fusion protein as well as purified Sfb protein competitively inhibited fibronectin binding and epithelial cell adherence of S. pyogenes, whereas streptococcal lipoteichoic acid (LTA), previously suggested to be the adhesin of S. pyogenes, had no effects. Southern blot analysis of chromosomal DNA from various streptococci revealed that the gene coding for the binding domain of Sfb protein was also present in other S. pyogenes strains. These results indicate that fibronectin-binding protein is the major adhesin of S. pyogenes.

Nontypeable Haemophilus influenzae disease: epidemiology, pathogenesis, and prospects for prevention

Nontypeable Haemophilus influenzae has emerged as an important human pathogen and is associated with a wide range of diseases. As methods for subtyping isolates have improved, our understanding of the epidemiology and pathogenesis of nontypeable H. influenzae disease has grown. These advances have facilitated identification of a number of bacterial factors with potential as vaccine components. In this review we discuss methods of classifying nontypeable H. influenzae, the epidemiology of disease due to these organisms, bacterial and host factors contributing to disease pathogenesis, and the status of efforts to develop an effective vaccine.

[The outlook for developing recombinant vaccines based on mycobacteria]

The paper provides the data available in the literature on the present-day direction in exploitation of recombinant vaccines on the basis of Mycobacterium spp. Special attention is paid to the nature of shuttle vectors for Mycobacterium spp. and E. coli.

Protective activity of antisera against isolates of Borrelia burgdorferi from various geographical origins

Antisera from rabbits immunized with two Japanese strains of Borrelia burgdorferi, HP3 an isolate from Ixodes persulcatus and HO14 an isolate from I. ovatus, or the European strain P/Bi isolated from human cerebrospinal fluid (CSF) did not passively protect hamsters from challenge with the infectious strain 297, a North American isolate from patient CSF. Antisera to strains 297 and B31, a North American isolate from I. dammini, however, provided protective effect to challenge with strain 297. Immune mice sera in the presence of homologous B. burgdorferi antigen induced the production of oxygen intermediates from mouse peritoneal exudate cells. Heterologous B. burgdorferi antigen had no effect. These results suggest that antigenic properties of Japanese strains are different from those of North American and European isolates.

Construction of an aroA mutant of Salmonella serotype Gallinarum: its effectiveness in immunization against experimental fowl typhoid

An aroA mutant was produced from a virulent strain of Salmonella Gallinarum, the causative agent of fowl typhoid in poultry, by Tn10 insertional inactivation and deletion. The mutant was highly attenuated for chickens. A single intramuscular immunization of 2-week-old chickens with 10(7) mutant organisms reduced mortality following oral challenge with 10(8) organisms of the parent strain from 63 to 30%. In a second experiment multiple immunizations with 10(8) mutant organisms reduced mortality after challenge with 10(7) organisms of the virulent strain from 77 to 0%. By oral inoculation the mutant was not able to immunize chickens against oral challenge.

Enterotoxicity and immunological properties of two mutant forms of Escherichia coli STIp with lysine or arginine substituted for the asparagine residue at position 11

Two variants of Escherichia coli heat-stable enterotoxin Ip, in which the amino acid residue at position 11 was substituted with lysine or arginine, were purified to near homogeneity from the culture supernatants of toxin-producing mutant strains. Neither the purified heat-stable enterotoxin Ip(Lys-11) nor the purified heat-stable enterotoxin Ip(Arg-11) showed a positive response in the suckling mouse assay or in the mouse intestinal loop assay. Furthermore, live bacteria producing these mutant heat-stable Ip enterotoxins did not cause fluid accumulation in mouse intestinal loops, in contrast to bacteria producing native heat-stable enterotoxin Ip. Nevertheless, antisera raised against both heat-stable enterotoxin Ip(Lys-11) and heat-stable enterotoxin Ip(Arg-11) neutralized the enterotoxic activity of native heat-stable enterotoxin Ip. These results demonstrate that heat-stable enterotoxin Ip(Lys-11) and heat-stable enterotoxin Ip(Arg-11) lose enterotoxicity but retain epitopes which are common to native heat-stable enterotoxin Ip.

[Experience in using an autovaccine in treating patients with chronic osteomyelitis]

Autovaccine immunization (AI) of 60 patients with chronic osteomyelitis resulted in 93% success (significant in 43%) in formerly failures both with surgical and medical treatment. The method of manufacturing the autovaccine is described, immunization schemes are given.

Development of an immunoassay using recombinant maltose-binding protein-STa fusions for quantitating antibody responses against STa, the heat-stable enterotoxin of Escherichia coli

A set of fusion proteins containing heat-stable enterotoxin (STa) and maltose-binding protein were engineered. These molecules were readily purified and used as solid-phase antigens in an enzyme-linked immunosorbent assay to monitor anti-STa responses in mice immunized with a recombinant vaccine composed of STa and the B subunit of heat-labile enterotoxin.

Bacterial vaccines: old and new, veterinary and medical

Developments in veterinary and medical bacterial vaccines are outlined. In the former case, economic considerations are paramount, and cruder, less purified products of proven efficacy continue to be employed. For human use, however, safety and absence of side effects are increasingly demanded. Various examples of human and veterinary vaccines are discussed, and interaction between the two fields is illustrated by reference to the pig-bel disease in New Guinea and the possible aetiology of Sudden Infant Death Syndrome.

OmpB (osmo-regulation) and icsA (cell-to-cell spread) mutants of Shigella flexneri: vaccine candidates and probes to study the pathogenesis of shigellosis

Genetic and molecular data now available on the pathogenic properties of Shigella flexneri allow rational design of live attenuated vaccine strains. The genes required at given steps of the infection process can be selectively mutated to impair the bacterium's capacity to interact with intestinal epithelial cells and/or survive within intestinal tissues in general. We have tested two mutations in S. flexneri serotype 5a (M90T) which, alone or in combination, have yielded promising results when evaluated as vaccine prototypes in orally infected macaque monkeys. The first mutation, icsA, blocks intracellular and cell-to-cell spread of the micro-organism. This mutant (SC560) appeared reasonably well tolerated and elicited protection against homologous challenge. The second mutation, ompB, disconnects the bacterium from one of its major environmental regulatory factors, osmolarity. This mutant (SC433) still caused slight dysenteric symptoms in vaccinees. It was also perfectly protective. When these two mutations were combined, the double mutant (SC445), was perfectly tolerated but failed to protect one out of five animals. These studies bring interesting prospects of the possibility of immunizing against shigellosis. In addition to providing new possibilities for vaccine design, construction and evaluation of these mutants allowed substantial progress in understanding the pathogenesis of shigellosis.

[The action of ribosomal preparations on nonspecific resistance to bacterial infection and on early tolerance to endotoxic shock]

Ribosomal preparations from Shigella flexneri and Shigella sonnei, introduced parenterally into mice, enhance their resistance to infection with the causative agents of typhoid fever and staphylococci. This effect is considerably less pronounced than that produced by the preparation of homologous lipopolysaccharide isolated by Boivin's method. After the administration of ribosomes nonspecific resistance to bacterial infective agents lasts for a short time. Ribosomal preparations do not enhance the resistance of mice to the lethal action of endotoxin.

Recombinant derivatives of Pasteurella multocida toxin: candidates for a vaccine against progressive atrophic rhinitis

Potential vaccine components for protection against atrophic rhinitis in pigs were developed. This was achieved by deletion mutagenesis of the gene encoding the Pasteurella multocida toxin. Four purified toxin derivatives lacking different and widely separated regions in the amino acid sequence were characterized by a lack of toxic activity. One such component was shown to induce efficient protection of vaccinated female mice and their offspring against challenge with purified P. multocida toxin.

Stable Listeria monocytogenes live vaccine candidate strains with graded attenuation on the mouse model

Metabolic drift (antibiotics resistance) mutations were used to construct stable two (and three) marker vaccine candidate strains of the predominant Listeria monocytogenes serotypes 1/2a and 4b by stepwise selection. Derived from wild-type strains, spontaneous chromosomal streptomycin-resistant clones with their i.p. LD50 elevated from less than or equal to 10(5.0) c.f.u. to approximately 10(6.1) c.f.u. were used in the second step to isolate the rifampicin-resistant mutants with i.p. LD50 values ranging from 10(6.6) to 10(7.4). On i.p. immunization with fully tolerated doses (less than or equal to 1% LD50), these potential vaccine strains were found to protect not less than 95% of the mice against a lethal (approximately 100 LD50) challenge with the homologous wild-type strain. Further elevation of the i.p. LD50 to greater than 10(8.3) c.f.u. by means of a third attenuating fosfomycin-resistance marker resulted in overattenuation and reduced protective capacity.

New trends in the use of Al(OH)3-conjugated endotoxins and their subunits from the S- and R-forms of Shigella dysenteriae serovar 1 for model vaccination purposes

The lipopolysaccharides, lipopolysaccharide-protein complexes and their lipids A, isolated from Shigella dysenteriae 1, exhibited lethal toxicity (LD50 300-400 micrograms per mouse), pyrogenicity (0.01-1.0 microgram), activity in the Limulus test (10(-3)-10(-12) mg ml-1) and produced a positive local Shwartzman reaction. It was found that these substances bound to Al(OH)3 were capable of successfully protecting mice from challenge with both homologous and heterologous infections (up to 90% of mice survived a challenge with LD100), whereas immunization with substances with no biological carrier exhibited very low or zero protective effects. Furthermore, the positive cross-reactivity of lipids A in the agar immunodiffusion test confirms the wide applicability for vaccination purposes.

Vaccine containing iron-regulated proteins of Pasteurella haemolytica A2 enhances protection against experimental pasteurellosis in lambs

A vaccine containing sodium salicylate extract (SSE) of Pasteurella haemolytica A2 cells grown in a medium chemically depleted of available iron by the addition of alpha alpha dipyridyl to induce iron-regulated proteins (IRPs) conferred protection to specific pathogen-free (SPF) lambs exposed to an aerosol of P. haemolytica A2. The disease score in these lambs was significantly lower (p less than 0.005) than those in unvaccinated lambs or in lambs immunized with SSE prepared from cells grown in iron-replete medium. Immunoblotting of sera from these SPF lambs against whole cell antigens of P. haemolytica A2 grown under iron-restricted conditions demonstrated that antibodies to IRPs were present only in the sera of animals immunized with SSE-IRP. The antibody profile of sera from the SSE-IRP group was similar to that obtained with serum from a lamb which had recovered from P. haemolytica A2 disease produced experimentally. Negligible levels of cytotoxin-neutralizing and bactericidal antibodies were detectable in the SSE-IRP group and therefore appear not to be involved in the protection observed in this experiment.

Research priorities for diarrhoeal disease vaccines: memorandum from a WHO meeting

Diarrhoeas caused by rotaviruses, Shigella, Vibrio cholerae, and enterotoxigenic Escherichia coli (ETEC) represent a major health burden in developing countries, and have stimulated much effort towards vaccine development in order to protect against these four disease agents. This Memorandum describes the state of the art and points the way to future research and test trials in this area.

Immunoprophylaxis of otitis media

Prospects for an effective otitis media vaccine are bolstered by a number of encouraging observations. Results of pneumococcal polysaccharide vaccine trials beginning in 1975, the enormously enhanced immunogenicity of protein-Hib polysaccharide coupled vaccines in infants, and the apparent effectiveness of a protein-PCP coupled vaccine in experimental otitis media suggest that a pneumococcal vaccine targeted to prevent invasive and middle ear infections is not too distant. The identification of several conserved surface antigens on NTHi and demonstration of otitis media protection elicited by these antigens in an animal model give promise for the development of H. influenzae vaccines for otitis media. Evidence that attenuated influenza A virus vaccination may also be an effective strategy for otitis media prevention, at least in an animal model, suggests that priority should be given to testing the efficacy of influenza, parainfluenza and respiratory syncytial virus vaccines with respect to otitis media prevention. It seems quite likely that not one but several immunoprophylaxis approaches will be necessary to reduce the overall incidence of otitis media given the multifactorial nature of the disease. Increasing parent and physician concern with the high incidence of otitis media and its morbidity suggests high participation rates in vaccine trials and high utilization of vaccines shown to be protective. Even if a vaccine could reduce the incidence of otitis media by 30%, an annual health care savings of $300-750 million would be achieved.

Environmental regulation of bacterial virulence — implications for vaccine design and production

There is now overwhelming evidence that many of the crucial virulence determinants of pathogenic bacteria are environmentally regulated and expressed only under certain conditions. Much progress is currently being made in identifying these factors and in understanding the molecular mechanisms controlling their production. This information is crucial for the understanding of microbial pathogenicity and it has important practical implications for vaccine design and production.

Construction of aromatic dependent Shigella flexneri 2a live vaccine candidate strains: deletion mutations in the aroA and the aroD genes

Live Shigella flexneri 2a vaccine candidate strains with deletion mutations in the aro genes were constructed. Tn10-generated auxotrophic mutations were transduced from Escherichia coli to S. flexneri 2a with bacteriophage P1CmCts. The tetracycline-sensitive derivatives of Tn10 mutants obtained were selected on Bochner's medium and checked by DNA-DNA hybridization using aroA and aroD gene specific probes. The vaccine candidate strains were tested to assess the efficacy of protection in guinea-pig conjunctival epithelia (Sereny test). The strains did not cause keratoconjunctivitis and exhibited significant protection in the challenge experiments. A candidate vaccine strain (delta aroD) showed 100% protection against 10(7) c.f.u. of wild type strain in the immunized guinea-pigs.

[The sorption of a protein-polysaccharide complex isolated from Neisseria meningitidis serogroup B on aluminum hydroxide gels and the immunological activity of the sorbed preparations]

The protein-polysaccharide complex, isolated from group B N. meningitidis, is a variant of vaccine for the prophylaxis of group B N. meningitidis infection. In this investigation the influence of the complex of the physical properties of aluminium hydroxide gels, the amount of gel, pH and the duration of sorption on the process of sorption has been studied. Aluminium hydroxide has been shown to produce a stimulating effect on the response of mice to the polysaccharide and protein contained in the complex after immunization made in two injections. Gels with a smaller particle size have been found to possess greater adjuvant activity, as well as greater absorbing activity. The immunological activity of the complex, adsorbed ex tempore, has proved to be no different from that of the complex adsorbed in an hour.

Modified Feist broth as a serum-free alternative for enhanced production of protective antigen of Erysipelothrix rhusiopathiae

The production of protective antigen in modified serum-free nutrient broth (H. Feist, K.-D. Flossmann, and W. Erler, Arch. Exp. Veterinaermed. 30:49-57, 1976) and in brain heart infusion broth supplemented with 10% horse serum (BHIS) was evaluated for six strains of Erysipelothrix rhusiopathiae serotypes 1a, 2, 2b, 4, and N. All six strains grew to higher cell densities in modified Feist medium than in BHIS and produced larger amounts of 64,000- to 66,000- and 39,000- to 40,000-molecular-weight antigens involved in immunity to erysipelas. A vaccine produced in Feist medium from E. rhusiopathiae SE-9 (serotype 2) was highly effective in a mouse protection test. We therefore suggest that modified Feist medium is an excellent, if not superior, alternative to BHIS for production of erysipelas vaccine.