The Mycobacterium bovis BCG vaccine for commercial use is classically produced as surface pellicles by culture on synthetic medium. Under these conditions, reproducibility of the cultures and quality assessment are hampered by slow growth of the bacilli, the formation of bacterial aggregates and a high proportion of dead bacilli after processing and final formulation of the vaccine. Here, we established dispersed cultures of M. bovis BCG in synthetic media in small-scale bioreactors. These cultures allow recording and adjusting of culture parameters and give rise to single bacilli with a high degree of live bacteria. In the murine model, bioreactor-grown M. bovis BCG exhibited slightly stronger replication and persistence than the vaccine produced under the classical conditions. The protective efficacy against challenge with M. tuberculosis was identical for both vaccine preparations.

In search of protective antigens which can be used in a vaccine to prevent Helicobacter pylori infection, we report on the identification of four genes, hopV, hopW, hopX and hopY, and the characterization of the corresponding proteins which belong to the H. pylori outer membrane protein (Hop) family containing 32 homologous members, some of which were shown to function as porins. Sequence analysis of 16 different H. pylori strains revealed that the proteins HopV, HopW, HopX and HopY are highly conserved. Localization of HopV, HopW, HopX and HopY at the surface of the bacteria was investigated by immunofluorescence. Using a planar lipid bilayer system the proteins HopV and HopX were shown to form pores with single-channel conductances of 1.4 and 3.0 nS, respectively.

In a prospective, controlled, randomized, multicenter study the immunogenicity of a single (day 0) and two (day 0, 28) booster vaccination against diphtheria were compared in subjects who had received their last diphtheria vaccination more than 10 years ago. Both short-term and long-term immunogenicity was assessed by determining diphtheria antitoxin levels four weeks after vaccination and after one and two years. 102 subjects received the first booster vaccination, and 83 were vaccinated twice. Prior to the first vaccination 27% of the subjects had a diphtheria antitoxin level below 0.01 I.U./ml; after the first booster only 5% were unprotected. The second booster did not show a significant effect, however, in 1 of the 5 subjects who were still unprotected after the first booster the second elicited an antitoxin level of more than 0.01 I.U./ml. After one and two years 7% and 8% of the subjects had diphtheria antitoxin level below 0.01 I.U./ml. A serological effect of a second booster vaccination four weeks after the first one could not be demonstrated neither after one nor after two years.

Three different variants of the recombinant hybrid outer membrane protein OprF (aa 190-342)-OprI (aa 21-83) could be obtained in high yield after expression in Escherichia coli. The hybrid protein was modified N terminally, either with a minimal histidine tag or with a homologous sequence of OprF. Both recombinant proteins were purified by nickel chelate affinity chromatography under native and denaturing conditions, and this produced three suitable candidates for a vaccination trial, protein His-F-I, which was purified in its native as well as in its refolded form; and the native purified N terminally extended protein, ex-F-I. In mice, significantly higher antibody titers and survival rates after challenge with Pseudomonas aeruginosa were observed following immunization with protein His-F-I, purified under native conditions.

Neisseria meningitidis is a major cause of bacterial septicemia and meningitis. Sequence variation of surface-exposed proteins and cross-reactivity of the serogroup B capsular polysaccharide with human tissues have hampered efforts to develop a successful vaccine. To overcome these obstacles, the entire genome sequence bf a virulent serogroup B strain (MC58) was used to identify vaccine candidates. A total of 350 candidate antigens were expressed in Escherichia coli, purified. and used to immunize mice. The sera allowed the identification of proteins that are surface exposed, that are conserved in sequence across a range of strains, and that induce a bactericidal antibody response, a property known to correlate with vaccine efficacy in humans.

A hybrid protein [Met–Ala–(His)6 OprF190–342–OprI21–83] consisting of the mature outer membrane protein I (OprI) and amino acids 190–342 of OprF of Pseudomonas aeruginosa was expressed in Escherichia coli and purified by Ni2+ chelate-affinity chromatography. After several studies in healthy volunteers, as well as in patients, had proven the tolerability and immunogenicity of the the OprF–OprI vaccine, after intra-muscular application, we developed an emulgel for intranasal immunization. For this purpose we combined a highly concentrated OprF–I with sodiumdodecylsulfate as vehicle and the gel matrix natriumlauryl sulfate. After safety and pyrogenicity evaluations in animals, eight healthy adult human volunteers received the OprF–I gel intranasally three times at 2-week intervals. The vaccination was well tolerated and no side effects were observed. An antibody induction (IgG and IgA) could be detected in the sera. These data support continued clinical investigation of the protection against infections in cystic fibrosis patients and patients prone to P. aeruginosa infections.

In a prospective, controlled, randomized, multicenter study the immunogenicity and tolerance of a single vaccination (day 0) and two (day 0, 28) booster vaccinations against diphtheria were compared in subjects who had received their last diphtheria vaccination more than 10 years ago. 415 subjects received the first booster vaccination, and 203 were vaccinated twice. The geometric mean diphtheria antitoxin concentration after the first booster (day 28) was 2.354 I.U./ml, and after the second booster (day 56) 2.238 I.U./ml. Prior to the first vaccination 48.9% of the subjects had a diphtheria antitoxin level below 0.1 I.U./m; after the first and second boosters 95.4% and 97.5% of subjects, respectively, showed a level of at least 0.1 I.U./ml. A clear serological effect of a second booster 4 weeks after the first one could not be demonstrated.

Among the numerous targets which can be used for the development of vaccines against Pseudomonas aeruginosa we focused on the outer membrane proteins OprF and OprI. The C-terminal part of OprF from aa 190 to aa 350 was investigated for its conservation and its localization of B-cell epitopes. A hybrid protein which combines the protective epitopes of OprF and OprI was expressed in E. coli and was proven to be highly protective against an intraperitoneal challenge with P. aeruginosa by active immunization of immunocompromised mice as well as by passive immunization of SCID mice with specific antisera. A purification procedure of the N-terminal His-tagged hybrid antigen was established using immobilized-metal-affinity chromatography. To evaluate its safety and immunogenicity the recombinant protein was purified for the immunization of human volunteers. The OprF/OprI hybrid protein is considered to be a candidate for a vaccine against P. aeruginosa.

From a sarkosyl-insoluble outer membrane fraction prepared from the Helicobacter pylori strain ATCC 43504, 19 proteins could be sequenced N-terminally by Edman degradation. Oligonucleotides were deduced and used for screening of a genomic library. From the isolated genes, five code for different members of a H.pylori outer membrane protein (Hop) family. Among these, the hopZ gene was characterized in more detail. It encodes a protein which was shown to be located at the bacterial surface by immunofluorescence studies. Sequence analysis of the hopZ gene from 15 different H.pylori strains revealed the existence of two alleles and the possible regulation of hopZ expression by slipped-strand mispairing within a CT dinucleotide repeat motif located in the signal-peptide coding region. Among the different strains, the influence of this region on the expression of HopZ was analyzed on a translational level by western blot analysis of bacterial extracts and immunofluorescence studies on intact cells. The protein is expressed only in those strains in which the number of the CT dinucleotide repeats allow for an open reading frame encoding the complete protein. Addionally the function of HopZ was investigated in an adhesion assay. The wild-type strain ATCC 43504 adhered to human gastric epithel cells whereas a knockout mutant strain showed significantly reduced binding to the cells.

ABSTRACT Plasmodium falciparum antigens SERP, HRPII, MSAI, and 41-3 have shown promise as vaccine components. This study aimed at reproducing and extending previous results using three hybrid molecules. Antibody responses were reproduced in Aotus monkeys, but solid protection from a P. falciparum blood-stage challenge that showed an unintendedly enhanced pathogenicity was not observed.

In einer prospektiven, kontrollierten, randomisierten, internationalen multizentrischen Studie wurde die Immunogenität und Toleranz einer einmaligen Boosterimpfung (Tag 0) mit einer zweimaligen Impfung (Tag 0, 28) gegen Diphtherie verglichen. 415 Probanden, bei denen die letzte Diphtherie-Impfung mindestens zehn Jahre zurücklag, erhielten eine erste Auffrischung, und 203 von ihnen wurden 28 Tage später erneut geimpft. Vor der ersten Auffrischimpfung betrug der mittlere geometrische Antikörpertiter (GMT) 0,077 I.E./ml, nach dem ersten Booster 2,354 I.E./ml und nach der zweiten Impfung wurde ein GMT von 2,238 I.E./ml gemessen. Vor der ersten Impfung hatten 48,9% der Probanden einen Antitoxinpiegel von weniger als 0,1 I.E./ml und 23,4% waren ungeschützt (<0,01 I.E./ml). Nach dem ersten Booster erhöhte sich der Anteil der Geschützten (≥0,1 I.E/ml) auf 95,4%, nach dem zweiten Booster auf 97,5%. Ein serologischer Effekt einer zweiten Boosteriumpfung vier Wochen nach der ersten konnte nicht nachgewiesen werden.

A mixture of Plasmodium falciparum exoantigens inducing lymphocyte activation and cytokine production was shown to contain the malaria vaccine candidate, the serine-stretch protein. This protein was shown serologically to correspond to Ag2, an exoantigen recognized by antibodies linked with protection against malaria. The glycophorin-binding protein, the histidine-rich protein II, the S-antigen, the heat shock protein 70, the ring-infected erythrocyte surface antigen, and the apical membrane antigen-1 were also shown serologically to be present in the mixture of exoantigens.