Outer membrane vesicles extracted from Neisseria meningitidis serogroup X for prevention of meningococcal disease in Africa.

Meningococcal disease is caused mainly by serogroups A, B, C, Y, W of N. meningitidis. However, numerous cases of meningitis caused by serogroup X N. meningitidis (MenX) have recently been reported in several African countries. Currently, there are no licensed vaccines against this pathogen and most of the MenX cases have been caused by meningococci from clonal complex (c.c) 181. Detergent extracted meningococcal outer membrane vesicle (dOMV) vaccines have previously shown to be safe and effective against epidemics of serogroup B meningococcal disease in all age groups. The aim of this work is therefore to obtain, characterize and evaluate the vaccine potential of dOMVs derived from a MenX strain (OMVx). Three experimental lots of OMVx were prepared by deoxycholate extraction from the MenX strain BF 2/97. Size and morphology of the vesicles was determined by Dynamic Light Scattering and electron microscopy, whereas the antigenic composition was characterized by gel electrophoresis and immunoblotting. OMVx were thereafter adsorbed to aluminium hydroxide (OMVx/AL) and two doses of OMVx were administered s.c. to groups of Balb/c mice three weeks apart. The immunogenicity and functional antibody activities in sera were evaluated by ELISA (anti-OMVx specific IgG responses) and serum bactericidal activity (SBA) assay. The size range of OMVx was shown to be between 90 and 120nm, whereas some of the antigens detected were the outer membrane proteins PorA, OpcA and RmpM. The OMVx/AL elicited high anti-OMVx antibody responses with bactericidal activity and no bactericidal activity was observed in the control group of no immunised mice. The results demonstrate that OMVx are immunogenic and could form part of a future vaccine to prevent the majority of meningococcal disease in the African meningitis belt.

The meningococcal vaccine candidate neisserial surface protein A (NspA) binds to factor H and enhances meningococcal resistance to complement.

Complement forms an important arm of innate immunity against invasive meningococcal infections. Binding of the alternative complement pathway inhibitor factor H (fH) to fH-binding protein (fHbp) is one mechanism meningococci employ to limit complement activation on the bacterial surface. fHbp is a leading vaccine candidate against group B Neisseria meningitidis. Novel mechanisms that meningococci employ to bind fH could undermine the efficacy of fHbp-based vaccines. We observed that fHbp deletion mutants of some meningococcal strains showed residual fH binding suggesting the presence of a second receptor for fH. Ligand overlay immunoblotting using membrane fractions from one such strain showed that fH bound to a approximately 17 kD protein, identified by MALDI-TOF analysis as Neisserial surface protein A (NspA), a meningococcal vaccine candidate whose function has not been defined. Deleting nspA, in the background of fHbp deletion mutants, abrogated fH binding and mAbs against NspA blocked fH binding, confirming NspA as a fH binding molecule on intact bacteria. NspA expression levels vary among strains and expression correlated with the level of fH binding; over-expressing NspA enhanced fH binding to bacteria. Progressive truncation of the heptose (Hep) I chain of lipooligosaccharide (LOS), or sialylation of lacto-N-neotetraose LOS both increased fH binding to NspA-expressing meningococci, while expression of capsule reduced fH binding to the strains tested. Similar to fHbp, binding of NspA to fH was human-specific and occurred through fH domains 6-7. Consistent with its ability to bind fH, deleting NspA increased C3 deposition and resulted in increased complement-dependent killing. Collectively, these data identify a key complement evasion mechanism with important implications for ongoing efforts to develop meningococcal vaccines that employ fHbp as one of its components.

Investigating BB0405 as a novel Borrelia afzelii vaccination candidate in Lyme borreliosis.

BB0405 is a surface exposed Borrelia burgdorferi protein and its vaccination protected mice against B. burgdorferi infection. As BB0405 is highly conserved across different B. burgdorferi sensu lato species, we investigated whether vaccination with recombinant BB0405 or through intradermal bb0405 DNA tattoo vaccination could provide protection against different Borrelia species, specifically against Borrelia afzelii, the predominant B. burgdorferi sensu lato genospecies causing Lyme borreliosis across Eurasia. We immunized C3H/HeN mice with recombinant BB0405 or with a codon-optimized bb0405 DNA vaccine using the pVAC plasmid and immunized corresponding control groups mice with only adjuvant or empty vectors. We subsequently subjected these immunized mice to a tick challenge with B. afzelii CB43-infected Ixodes ricinus nymphs. Upon vaccination, recombinant BB0405 induced a high total IgG response, but bb0405 DNA vaccination did not elicit antibody responses. Both vaccine formulations did not provide protection against Borrelia afzelii strain CB43 after tick challenge. In an attempt to understand the lack of protection of the recombinant vaccine, we determined expression of BB0405 and showed that B. afzelii CB43 spirochetes significantly and drastically downregulate the expression of BB0405 protein at 37 °C compared to 33 °C, where as in B. burgdorferi B31 spirochetes expression levels remain unaltered. Vaccination with recombinant BB0405 was previously shown to protect against B. burgdorferi sensu stricto. Here we show that vaccination with either recombinant BB0405 (or non-immunogenic bb0405 DNA), despite being highly conserved among B. burgdorferi sl genospecies, does not provide cross-protection against B. afzelii, mostly likely due to downregulation of this protein in B. afzelii in the mammalian host.

Highly conserved Neisseria meningitidis surface protein confers protection against experimental infection.

A new surface protein, named NspA, which is distinct from the previously described Neisseria meningitidis outer membrane proteins was identified. An NspA-specific mAb, named Me-1, reacted with 99% of the meningococcal strains tested indicating that the epitope recognized by this particular mAb is widely distributed and highly conserved. Western immunoblotting experiments indicated that mAb Me-1 is directed against a protein band with an approximate molecular mass of 22,000, but also recognized a minor protein band with an approximate molecular mass of 18,000. This mAb exhibited bactericidal activity against four meningococcal strains, two isolates of serogroup B, and one isolate from each serogroup A and C, and passively protected mice against an experimental infection. To further characterize the NspA protein and to evaluate the protective potential of recombinant NspA protein, the nspA gene was identified and cloned into a low copy expression vector. Nucleotide sequencing of the meningococcal insert revealed an ORF of 525 nucleotides coding for a polypeptide of 174 amino acid residues, with a predicted molecular weight of 18,404 and a isoelectric point of 9.93. Three injections of either 10 or 20 microg of the affinity-purified recombinant NspA protein efficiently protected 80% of the mice against a meningococcal deadly challenge comparatively to the 20% observed in the control groups. The fact that the NspA protein can elicit the production of bactericidal and protective antibodies emphasize its potential as a vaccine candidate.

Current State of Modern Biotechnological-Based Aeromonas hydrophila Vaccines for Aquaculture: A Systematic Review.

This systematic review describes what "the cutting edge vaccines for Aeromonas hydrophila are". The focus is on types of high tech biotechnological based vaccines, target gene or antigen in developing these vaccines, and challenge model fish species used in vaccines efficacy testing. Vaccines delivery methods, immune response, and their efficacy, adjuvant or carrier systems used, and the overall experimental setup or design of the vaccines under investigation are also described. The search for the original papers published between 2009 and 2018 was conducted in June of 2018, using the PubMed and Google scholar electronic database. Twenty-three (23/4386) studies were included in the final assembly using PRISMA guidelines (Protocol not registered). Recombinant protein vaccines were the highly experimented type of the modern biotechnological based vaccines identified in the selected studies (16/23; 70%). Outer membrane proteins (OMPs) of different ß-barrels were shown to be a potential antigenic entity for A. hydrophila vaccines (57%). Intraperitoneal route with conventional carries or adjuvants was the highly applied delivery system while very few studies used herbal based vaccine adjuvants and nanomaterial as a vaccine carrier. Variation was observed in terms of protection levels in the selected studies. The experimental designs partly contributed to the observed variation. Therefore, recombinant vaccines that use new carrier system technologies and delivered through oral route in feeds would have been of great value for use in the prevention and control of A. hydrophila infections in fish. Despite the usefulness as academic tools to identify what is important in pathogenicity of the etiological agent to the host fish, these vaccines are only economically viable in very high-value animals. Therefore, if vaccination is a good option for A. hydrophila group, then simple autogenous vaccines based on accurate typing and evidence-based definition of the epidemiological unit for their use would be the most viable approach in terms of both efficacy and economic feasibility especially in low and middle-income countries (LMIC).

Anti-tumor activity of Acinetobacter baumannii outer membrane protein A on dendritic cell-based immunotherapy against murine melanoma.

Acinetobacter baumannii outer membrane protein A (AbOmpA) is a major surface protein that is an important pathogen-associated molecular pattern. Based on our previous findings that AbOmpA induced the phenotypic maturation of dendritic cells (DCs) and drove the Th1 immune response in vitro, we investigated the therapeutic efficacy of AbOmpA-pulsed DC vaccines in a murine melanoma model. The surface expression of co-stimulatory molecules (CD80 and CD86) and major histocompatibility complex class I and II molecules was higher in DCs pulsed with AbOmpA alone or with a combination of B16F10 cell lysates than that of DCs pulsed with B16F10 cell lysates. AbOmpA stimulated the maturation of murine splenic DCs in vivo. In a therapeutic model of murine melanoma, AbOmpA-pulsed DCs significantly retarded tumor growth and improved the survival of tumor-bearing mice. AbOmpA-pulsed DCs significantly enhanced CD8+, interleukin-2+ T cells and CD4+, interferon-gamma+ T cells in tumor-bearing mice. These results provide evidence that AbOmpA may be therapeutically useful in adjuvant DC immunotherapy against poorly immunogenic melanoma without tumor-specific antigens.

Omics and bioinformatics applied to vaccine development against Borrelia.

Borrelia burgdorferi is an extracellular spirochete that causes Lyme disease. Currently, no effective vaccine is available for humans and animals except for dogs. In the present study, an extensive bioinformatics pipeline was established to predict new candidates that can be used for vaccine development including building the protein-protein interaction network based on orthologues of experimentally verified protein-protein interaction networks, elucidation of the proteins involved in the immune response, selection of the topologically-interesting proteins and their prioritization based on their antigenicity. Proteomic network analysis yielded an interactome network with 120 nodes with 97 interactions. Proteins were selected to obtain a subnet containing only the borrelial membrane proteins and immune-related host proteins. This strategy resulted in the selection of 15 borrelial targets, which were subjected to extensive bioinformatics analysis to predict their antigenic properties. Based on the strategy applied in this study the proteins encoded by erpX (ErpX proteins, UniProt ID: H7C7L6), erpL (ErpL protein, UniProt ID: H7C7M3) and erpY (ErpY protein, UniProt ID: Q9S0D9) are suggested as a novel set of vaccine targets to control Lyme disease. Moreover, five different tools were used to validate their antigenicity regarding B-cells. The combination of all these proteins in a vaccine should allow improved protection against Borrelia infection.

Gal-Gal pili vaccines prevent pyelonephritis by piliated Escherichia coli in a murine model. Single-component Gal-Gal pili vaccines prevent pyelonephritis by homologous and heterologous piliated E. coli strains.

The initial pathogenic step in nonobstructive Escherichia coli pyelonephritis usually involves the binding of a bacterial adhesin with host uroepithelial glycoprotein receptors containing the D-Gal p alpha 1----4 D-Gal p beta 1 (Gal-Gal) moiety. In this study, groups of mice were immunized with Gal-Gal pili and challenged 2 wk later intravesicularly with E. coli strains expressing homologous or heterologous pili. 63 of 129 pili-immunized mice (49%) were protected from subsequent E. coli renal colonization compared with 5 of 85 control mice (6%). Among mice that had E. coli cultured from their right kidney, control mice had greater bacterial colony counts than pili-immunized animals (P less than 0.05). Light microscopic examination of kidneys demonstrated less histopathology among pili immunized mice than among control mice (P less than 0.05). Protection correlated with the presence of specific IgG antibodies in the urine and serum that bind to the major pilin structural polypeptide and not to the Gal-Gal pili tip adhesin per se. These results support the concept that immunization with a bacterial surface-coat constituent can prevent mucosal infection by interfering with colonization. Also Gal-Gal pili of E. coli represent a suitable candidate for immunoprophylaxis against pyelonephritis.

Protection against Staphylococcus aureus and tetanus infections by a combined vaccine containing SasA and TeNT­Hc in mice.

In developing countries, trauma patients and neonates are vulnerable to Staphylococcus aureus (S. aureus) and Clostridium tetani infections. It has been suggested that a combined vaccine against the two infections may be a reliable and cost­effective strategy. Previous studies have indicated that the S. aureus surface protein A (SasA) and the C fragment of tetanus neurotoxin (TeNT­Hc) may be suitable candidates for a vaccine against S. aureus and tetanus infections, respectively. In the present study, mice were immunized with a combined vaccine containing SasA and TeNT­Hc, which induced a robust immune response to both antigens, and mutual interference between SasA and TeNT­Hc was not observed. In the S.aureus challenge model, the combined vaccine fully protected BALB/c mice against lethal intraperitoneal challenges with 3x109 colony­forming units of a methicillin­resistant S. aureus USA300 strain. In the TeNT challenge model, the combined vaccine conferred complete protection against a lethal dose of (2x103) xLD50 tetanus toxin. These results implied that SasA and TeNT­Hc promising components for a combined vaccine against S. aureus and tetanus infections.

Bacterial Outer Membrane Vesicles as a Delivery System for Virulence Regulation.

Outer membrane vesicles (OMVs) are spherical nanostructures that are ubiquitously shed from gram-negative bacteria both in vitro and in vivo. Recent findings revealed that OMVs, which contain diverse components derived from the parent bacterium, play an important role in communication with neighboring bacteria and the environment. Furthermore, nanoscale proteoliposomes decorated with pathogen-associated molecules attract considerable attention as a non-replicative carrier for vaccines and drug materials. This review introduces recent advances in OMV biogenesis and discusses the roles of OMVs in the context of bacterial communication and virulence regulation. It also describes the remarkable accomplishments in OMV engineering for diverse therapeutic applications.

Impact of Reducing Complement Inhibitor Binding on the Immunogenicity of Native Neisseria meningitidis Outer Membrane Vesicles.

Neisseria meningitidis recruits host human complement inhibitors to its surface to down-regulate complement activation and enhance survival in blood. We have investigated whether such complement inhibitor binding occurs after vaccination with native outer membrane vesicles (nOMVs), and limits immunogenicity of such vaccines. To this end, nOMVs reactogenic lipopolysaccharide was detoxified by deletion of the lpxl1 gene (nOMVlpxl1). nOMVs unable to bind human complement factor H (hfH) were generated by additional deletions of the genes encoding factor H binding protein (fHbp) and neisserial surface protein A (NspA) (nOMVdis). Antibody responses elicited in mice with nOMVdis were compared to those elicited with nOMVlpxl1 in the presence of hfH. Results demonstrate that the administration of human fH to mice immunized with fHbp containing OMVlpxl1 decreased immunogenicity against fHbp (but not against the OMV as a whole). The majority of the OMV-induced bactericidal immune response (OMVlpxl1 or OMVdis) was versus PorA. Despite a considerable reduction of hfH binding to nOMVdis, and the absence of the vaccine antigen fHbp, immunogenicity in mice was not different from nOMVlpxl1, in the absence or presence of hfH (serum bactericidal titers of 1:64 vs 1:128 after one dose in the nOMVdis and nOMVlpxl1-immunized groups respectively). Therefore, partial inhibition of fH binding did not enhance immunity in this model.

Adjuvanted Lyme disease vaccine: a review of its use in the management of Lyme disease.

UNLABELLED: Lyme disease is a potentially serious infection which is caused by the spirochaete Borrelia burgdorferi and is endemic in certain areas of North America, Europe and Asia. Lyme disease vaccine (LYMErix) is an adjuvanted formulation of the outer surface protein A (OspA) of the causative spirochaete. It acts by inducing high titres of anti-OspA antibodies (anti-OspA), which must be present in vaccinated individuals before exposure to B. burgdorferi to provide protection against Lyme disease. Lyme disease vaccine efficacy against Lyme disease was 80% for definite and asymptomatic cases and 76% for definite cases at year 2 using the recommended dosage regimen [30 microg at months 0, 1 and 12 (0, 1, 12 schedule)] in a randomised, double-blind, multicentre trial in 10,936 enrolled adult volunteers who resided in areas of the US endemic for Lyme disease. On the basis of an anti-OspA correlate of protection, Lyme disease vaccine 30 microg was equally effective when administered by a shorter schedule (0, 1, 6 schedule); > or = 90% of adult volunteers developed protective anti-OspA titres with this or the 0, 1, 12 schedule. Although published data are fewer, a 0, 1, 2 schedule has also shown promise in adults. In addition, virtually all children (aged 2 to 15 years) given Lyme disease vaccine 30 microg developed protective anti-OspA titres, but published data are also limited and results of a large paediatric trial are awaited with interest. Long term protection against Lyme disease appears to be possible with Lyme disease vaccine. Although anti-OspA titres decline rapidly after completion of the recommended schedule, booster doses of 30 microg of the vaccine induced protective anti-OspA titres in > or = 96% of adult volunteers when administered 12 and/or 24 months later. Lyme disease vaccine 30 microg is well tolerated: most vaccination-related adverse events were transient and mild or moderate in severity in clinical trials. The most common spontaneously reported adverse event was pain at the injection site in 24% of vaccine recipients (vs 7.6% of the placebo group). The incidence of spontaneously reported, early nonspecific systemic adverse events was <4% but was higher with the vaccine than with placebo for some events (e.g. myalgias, fever and chills but not arthralgia). There appeared to be no association between the vaccine and the incidence of arthritis or any late systemic adverse events. The tolerability profile of Lyme disease vaccine did not appear to vary with the schedule of administration, nor to differ between adults and children. CONCLUSIONS: Lyme disease vaccine, an adjuvanted formulation of OspA, protects most adults against Lyme disease when administered by the recommended 0, 1, 12 schedule before disease exposure, and is well tolerated. The optimal schedule(s) of administration, duration of protection against Lyme disease, long term tolerability in adults and potential role in children are not fully defined for this vaccine. Lyme disease vaccine is indicated in North America for active immunisation of adults at moderate to high risk of contracting Lyme disease.

IgG subclass antibodies to serogroup B meningococcal outer membrane antigens following infection and vaccination.

IgG and IgG subclass antibodies to the outer membrane antigens from Neisseria meningitidis (serogroup B, serotype 15:P1.16) were quantitated by an enzyme-linked immunosorbent assay (ELISA) in sera from 40 patients with group B:15:P1.16 meningococcal disease and 24 volunteers immunized with a serotype 15:P1.16 outer membrane vesicle vaccine. A second injection was given 6 weeks after the first immunization. Patient sera obtained two and six weeks after onset of the disease had significantly higher levels of total IgG, IgG1, IgG2, and IgG3 antibodies to the outer membrane antigens than acute sera, convalescent sera from patients with systemic non-meningococcal bacterial infections and sera from healthy controls. The levels of total IgG and IgG1 remained high one and three years later. Sera from the vaccinees showed high levels of total IgG and IgG1 6, 12 and 26 weeks after the first immunization and high levels of IgG3 6 weeks after the second immunization. No increase of IgG2 or IgG4 levels was observed in the postimmunization sera. Immunoblotting of three convalescent sera demonstrated individual patterns of IgG subclass binding to various outer membrane antigens with most distinct binding of IgG1 and IgG3 antibodies to the class I protein, the H.8 lipoprotein and the lipopolysaccharide. Since IgG1 and IgG3 are the most effective antibodies for complement activation and phagocytosis, group B meningococcal disease and immunization with the serotype 15:P1.16 outer membrane vesicle vaccine stimulate production of those IgG subclasses which have the strongest opsonic and bactericidal activity.

Protective immunity induced by porin against Salmonella infection in mice.

Porin, a major outer membrane protein was purified from Salmonella typhimurium and its immune potential was studied in mice. Active immunization with porin induced about 45 per cent protection to an intravenous challenge with 10LD50 of S. typhimurium. Further, in porin immunized mice significant level of anti-porin antibodies and DTH reaction were detected. Attempts were also made to improve the immune potential of porin. Freund's complete adjuvant when mixed with immunogenic doses of porin enhanced the anti-porin antibody titre. However, it could not improve the protective ability of porin. On the other hand, porin when injected along with lipopolysaccharide (LPS) induced a higher level (55% survival with 50LD50) of protection than porin or LPS alone. This finding was also substantiated by the significantly reduced in vivo growth of challenge organisms in mice immunized with porin plus LPS. These results indicate that porin is a protective antigen and LPS significantly enhances the protective ability of porin.

Tick trouble: overview of tick-borne diseases.

Tick-borne diseases can be severe or even fatal, but when identified early, most can be easily treated. Tick-borne diseases often present with nonspecific symptoms. Therefore it is important for the primary care physician to be familiar with the epidemiology of these diseases and their presentations. Although Lyme disease is the most common and well-known of the many tick-borne diseases, Rocky Mountain spotted fever, ehrlichiosis, and babesiosis are also threats throughout the United States.

Differential effects of two different routes of immunization on protection against gram-negative sepsis by a detoxified Escherichia coli J5 lipopolysaccharide group B meningococcal outer membrane protein complex vaccine in a burned mouse model.

Gram-negative sepsis causes morbidity and mortality in burned patients. To determine whether immunization with core endotoxin (lipopolysaccharide) via one of two routes could protect burned mice from septic death, mice were immunized either three times subcutaneously (SC) or one time intramuscularly (IM) then two times intraperitoneally (IP) with a core-lipopolysaccharide vaccine. Control mice were immunized with either saline or an irrelevant antigen. Postimmunization, mice were immunocompromised with a 15% TBSA flame burn and challenged subeschar with Klebsiella pneumoniae or Escherichia coli. Vaccine immunization improved the survival of both E. coli- and K. pneumoniae-challenged mice when given SC but not when given IM, IP. Postimmunization, total immunoglobulin titers were elevated over preimmune titers, but titers in IM, IP-immunized mice were higher than those in SC-immunized mice. Both isotyping and flow cytometry studies indicated that sera from mice immunized via IM, IP opsonized better than sera from mice immunized via SC. Hence, this vaccine provided route-specific protection of burned mice against gram-negative sepsis; its mechanism of action was not solely dependent upon increased immunoglobulin titers or phagocytosis.

[Prevention of Lyme disease]. / Profilaktyka boreliozy z Lyme.

Over the last decade many researchers have turned much attention to the vaccine against Lyme disease as the only effective preventive method. Recently two groups of researchers have published data on their trials carried out on humans. The vaccine given to volunteers consisted of recombinant outer surface protein (Osp)A. A two-year observation of the persons studies revealed that 79% of them had developed resistance to Borrelia burgdorferi infection. These data were evaluated by the FDA experts who recommended the vaccine for general use with the following reservations that have to be elucidated: too short observation of vaccinated persons, no possibility to vaccinate children and the problem of vaccinating people with undiagnosed Lyme disease.

[The protective properties of a porin from the outer membrane of Yersinia pseudotuberculosis]. / Protektivnye svoistva porina iz vneshnei membrany Yersinia pseudotuberculosis.

The protective properties of the species-specific pore-forming polypeptide of Y. pseudotuberculosis outer membrane (porin) were studied. The study showed that 80-90% of mice immunized with porin survived after challenge with 10-30 LD50 of Y. pseudotuberculosis, serovars 1 and 3. The LD50 of the preparation exceeded its ED50 more than 100-fold. Immunization made in two injections was more effective than immunization in one injection. The immunization of the animals with porin led to an increase in the activity of peritoneal exudate macrophages with respect to Y. pseudotuberculosis, serovars 1 and 3.

Immunization with a Borrelia burgdorferi BB0172-derived peptide protects mice against lyme disease.

Lyme disease is the most prevalent arthropod borne disease in the US and it is caused by the bacterial spirochete Borrelia burgdorferi (Bb), which is acquired through the bite of an infected Ixodes tick. Vaccine development efforts focused on the von Willebrand factor A domain of the borrelial protein BB0172 from which four peptides (A, B, C and D) were synthesized and conjugated to Keyhole Limpet Hemocyanin, formulated in Titer Max® adjuvant and used to immunize C3H/HeN mice subcutaneously at days 0, 14 and 21. Sera were collected to evaluate antibody responses and some mice were sacrificed for histopathology to evaluate vaccine safety. Twenty-eight days post-priming, protection was evaluated by needle inoculation of half the mice in each group with 10³ Bb/mouse, whereas the rest were challenged with 105Bb/mouse. Eight weeks post-priming, another four groups of similarly immunized mice were challenged using infected ticks. In both experiments, twenty-one days post-challenge, the mice were sacrificed to determine antibody responses, bacterial burdens and conduct histopathology. Results showed that only mice immunized with peptide B were protected against challenge with Bb. In addition, compared to the other the treatment groups, peptide B-immunized mice showed very limited inflammation in the heart and joint tissues. Peptide B-specific antibody titers peaked at 8 weeks post-priming and surprisingly, the anti-peptide B antibodies did not cross-react with Bb lysates. These findings strongly suggest that peptide B is a promising candidate for the development of a new DIVA vaccine (Differentiate between Infected and Vaccinated Animals) for protection against Lyme disease.

Protection from hemolytic uremic syndrome by eyedrop vaccination with modified enterohemorrhagic E. coli outer membrane vesicles.

We investigated whether eyedrop vaccination using modified outer membrane vesicles (mOMVs) is effective for protecting against hemolytic uremic syndrome (HUS) caused by enterohemorrhagic E. coli (EHEC) O157:H7 infection. Modified OMVs and waaJ-mOMVs were prepared from cultures of MsbB- and Shiga toxin A subunit (STxA)-deficient EHEC O157:H7 bacteria with or without an additional waaJ mutation. BALB/c mice were immunized by eyedrop mOMVs, waaJ-mOMVs, and mOMVs plus polymyxin B (PMB). Mice were boosted at 2 weeks, and challenged peritoneally with wild-type OMVs (wtOMVs) at 4 weeks. As parameters for evaluation of the OMV-mediated immune protection, serum and mucosal immunoglobulins, body weight change and blood urea nitrogen (BUN)/Creatinin (Cr) were tested, as well as histopathology of renal tissue. In order to confirm the safety of mOMVs for eyedrop use, body weight and ocular histopathological changes were monitored in mice. Modified OMVs having penta-acylated lipid A moiety did not contain STxA subunit proteins but retained non-toxic Shiga toxin B (STxB) subunit. Removal of the polymeric O-antigen of O157 LPS was confirmed in waaJ-mOMVs. The mice group vaccinated with mOMVs elicited greater humoral and mucosal immune responses than did the waaJ-mOMVs and PBS-treated groups. Eyedrop vaccination of mOMVs plus PMB reduced the level of humoral and mucosal immune responses, suggesting that intact O157 LPS antigen can be a critical component for enhancing the immunogenicity of the mOMVs. After challenge, mice vaccinated with mOMVs were protected from a lethal dose of wtOMVs administered intraperitoneally, conversely mice in the PBS control group were not. Collectively, for the first time, EHEC O157-derived mOMV eyedrop vaccine was experimentally evaluated as an efficient and safe means of vaccine development against EHEC O157:H7 infection-associated HUS.