Particulate Cell Wall Materials of Lactobacillus acidophilus as Vaccine Adjuvant (original) (raw)
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Methods, 2006
Mucosal immunization with subunit vaccines requires new types of antigen delivery vehicles and adjuvants for optimal immune responses. We have developed a non-living and non-genetically modiWed gram-positive bacterial delivery particle (GEM) that has built-in adjuvant activity and a high loading capacity for externally added heterologous antigens that are fused to a high aYnity binding domain. This binding domain, the protein anchor (PA), is derived from the Lactococcus lactis AcmA cell-wall hydrolase, and contains three repeats of a LysM-type cell-wall binding motif. Antigens are produced as antigen-PA fusions by recombinant expression systems that secrete the hybrid proteins into the culture growth medium. GEM particles are then used as aYnity beads to isolate the antigen-PA fusions from the complex growth media in a one step procedure after removal of the recombinant producer cells. This procedure is also highly suitable for making multivalent vaccines. The resulting vaccines are stable at room temperature, lack recombinant DNA, and mimic pathogens by their bacterial size, surface display of antigens and adjuvant activity of the bacterial components in the GEM particles. The GEM-based vaccines do not require additional adjuvant for eliciting high levels of speciWc antibodies in mucosal and systemic compartments.
Frontiers in Microbiology, 2020
S-layers are bacterial structures present on the surface of several Gram-positive and Gram-negative bacteria that play a role in bacterial protection. In Lactobacillus acidophilus (L. acidophilus ATCC 4356), the S-layer is mainly composed of the protein SlpA. A tandem of two copies of the protein domain SLP-A (pfam: 03217) was identified at the C-terminal of SlpA, being this double SLP-A protein domain (in short dSLP-A) necessary and sufficient for the association of the protein to the L. acidophilus cell wall. A variety of proteins fused to the dSLP-A domain were able to spontaneously associate with high affinity to the cell wall of L. acidophilus and Bacillus subtilis var. natto, in a process that we termed decoration. Binding of dSLP-A-containing-proteins to L. acidophilus was stable at conditions that mimic the gastrointestinal transit in terms of pH, proteases, and bile salts. To evaluate if protein decoration of L. acidophilus can be adapted to generate an oral vaccine platform, a chimeric antigen derived from the bacterial pathogen Shiga-toxin-producing Escherichia coli (STEC) was constructed by fusing the sequences encoding the polypeptides EspA 36-192 , Intimin 653-953 , Tir 240-378 , and H7 flagellin 352-374 (EITH7) to the dSLP-A domain (EITH7-dSLP-A). Recombinantly expressed EITH7-dSLP-A protein was affinity purified and combined with L. acidophilus cultures to allow the association of the chimeric antigen to the bacterial surface. EITH7-decorated L. acidophilus was orally administered to BALB/c mice and the induction of anti-EITH7 specific antibodies in sera and feces determined by ELISA. Mice presenting significantly higher anti-EITH7 antibodies titers were able to control more efficiently an experimental STEC infection than mice that received the non-decorated L. acidophilus carrier, indicating that antigen-decorated L. acidophilus can be adapted as a mucosal immunization delivery platform to elicit a protective immune response for vaccine purposes.
Vaccine, 2007
Mucosal immunity plays a major role in the prevention of infectious diseases. Genetically engineered lactic acid bacteria (LAB) have been tested in the last 10 years as safe mucosal delivery vectors. We previously showed that intranasal co-administration of recombinant lactococci displaying human papillomavirus type 16 (HPV-16) E7 antigen at its surface (LL-E7) and secreting biologically active interleukine-12 (LL-IL-12) has therapeutic effects on HPV-16-induced tumors in mice. In this work, to optimize the immunization protocol, a comparison between intragastric and intranasal routes of administration was performed and two different LAB strains (Lactococcus lactis and Lactobacillus plantarum) were tested as delivery vector. E7-specific systemic and mucosal responses as well as potent anti-tumor effects were higher after intranasal immunization with LL-E7 and LL-IL-12 strains than intragastric administration. Comparisons of the immune responses induced by intranasal administration of either LL-E7 or Lb. plantarum anchoring E7 antigen (LP-E7) revealed highest systemic responses with recombinant Lactobacillus. Furthermore, although only a modest mucosal immune response was observed with LP-E7, this strain was able to induce a significant regression of HPV-induced tumors in contrast to LL-E7. Taken together, our results demonstrate the advantage of intranasal over intragastric route of immunization to induce an antigen-specific immune response and suggest that intrinsic immunomodulatory properties of Lb. plantarum play an important role in the immunogenicity of the expressed antigen.
Progress in the Development of Lactococcus lactis as a Mucosal Vaccine Delivery Vehicle
Lactococcus lactis, a food-grade, non-pathogenic, non-invasive, non-colonizing and " generally regarded as safe " lactic acid bacteria, is widely used in food, medicine, and husbandry industry, and it is a potential and promising candidate as a mucosal vaccine delivery vehicle (MVDV). This review describes the latest research progress of L. lactis as an MVDV and its potential improvements. Firstly, the review introduces the advantages of using L. lactis as an MVDV, emphasizing the efficient controlled protein expression and protein-targeting systems developed for production of a desired antigen. Secondly, an extensive overview is given of the progress made in improving production yield and stability of the heterologous proteins expressed in L. lactis. Thirdly, an overview is provided of the efficiency of L. lactis as MVDV for mucosal immunization. Finally, the problems limiting the use of L. lactis as MVDV are introduced and probable methods to solve them are brought forward.
Biotecnologia Aplicada
Developing an effective vaccine entails: 1) proper antigenic presentation to the immune system, inducing a response of adequate intensity 2) a long duration for said response 3) the ability to steer this response towards the immune system pattern most suited for the elimination of the pathogen. Among the current crop of adjuvants, only aluminum-based gels and some oil emulsions are compliant with established regulatory and safety requirements and, not surprisingly, have received extensive use. The present work describes the development of a technological framework for the inclusion of virus-like particles (VLP) as adjuvants in vaccine preparations, allowing the induction of a functional immune response in humans that achieves seroconversion and protective antibody levels without the need for additional adjuvants. This technological framework comprises both the production and formulation of antigens as virus-like particles and the use of these VLP as adjuvants for soluble antigens, o...
TURKISH JOURNAL OF VETERINARY AND ANIMAL SCIENCES, 2020
Infectious bronchitis (IB) is a notable disease of poultry flocks that results in economic loss. As a consequence of the presence of various IB virus (IBV) serotypes, control strategies, such as vaccination, should be replaced by provide broad protective immunity against the disease to date. Gram-positive enhancer matrix particles, or so-called bacterium like particles (BLPs), obtained from the bacterium Lactococcus lactis (L. lactis), have demonstrated an adjuvancy effect by providing demanding mucosal and humoral immune responses, as well as a protective cellular immunity whenever delivered admixed with a vaccine via intranasal or intraocular administration. In this study, for the first time, attempts were made to investigate the impact of an IBV vaccine supplemented by various doses of BLPs on induced levels of humoral immunity against IB. For this purpose, increasing doses of derived BLPs (0, 0.15, 0.3, and 0.6 mg dry weight per bird) were admixed with IBV live attenuated H120 serotype vaccine, and were delivered via ocular administration to 4 equal groups of 10 specific pathogen-free (SPF) chickens in 4 groups: control, BLP1, BLP2, and BLP3, respectively. In addition, 10 SPF chickens that were not immunized comprised the Unvaccinated group. Blood was collected from 5 members of each group weekly for 35 days. Levels of IgG antibodies in the sera were then assayed using ELISA. Weight gain and the feed conversion ratio of each group were also recorded weekly. Finally, 3 birds from each group were necropsied to evaluate probable lesions. The best results were obtained in the BLP1 group, with IBV vaccination at a low dose of admixed BLPs boosted immediate anti-IBV humoral responses; however, the results were not significantly different from those of the Control group, but were still feasible enough for application in the field. In conclusion, BLPs could be a desirable adjuvant for IBV vaccines to increase immunity in chickens.
Lactobacillus acidophilus as a live vehicle for oral immunization against chicken anemia virus
Applied Microbiology and Biotechnology, 2011
The AcmA binding domains of Lactococcus lactis were used to display the VP1 protein of chicken anemia virus (CAV) on Lactobacillus acidophilus. One and two repeats of the cell wall binding domain of acmA gene were amplified from L. lactis MG1363 genome and then inserted into co-expression vector, pBudCE4.1. The VP1 gene of CAV was then fused to the acmA sequences and the VP2 gene was cloned into the second MCS of the same vector before transformation into Escherichia coli. The expressed recombinant proteins were purified using a Histag affinity column and mixed with a culture of L. acidophilus. Whole cell ELISA and immunofluorescence assay showed the binding of the recombinant VP1 protein on the surface of the bacterial cells. The lactobacilli cells carrying the CAV VP1 protein were used to immunize specific pathogen-free chickens through the oral route. A moderate level of neutralizing antibody to CAV was detected in the serum of the immunized chickens. A VP1specific proliferative response was observed in splenocytes of the chickens after oral immunization. The vaccinated groups also showed increased levels of Th1 cytokines interleukin (IL)-2, IL-12, and IFN-γ. These observations suggest that L. acidophilus can be used in the delivery of vaccines to chickens.
Assessment of Lactobacillus gasseri as a Candidate Oral Vaccine Vector
Clinical and Vaccine Immunology, 2011
Lactobacillus species are commensal bacteria that have long been recognized as probiotic microbes and are generally regarded as safe (GRAS) for human consumption. We have investigated the use of L. gasseri as a vaccine vector for oral immunization against mucosal pathogens. Recent research has shown that the immune response to different lactobacilli can vary widely depending on the species or subspecies of Lactobacillus being studied. While some lactobacilli seem to induce oral tolerance, others induce an adaptive immune response. This study characterized the systemic and mucosal immune response to wild-type and genetically modified L. gasseri. L. gasseri primarily activates TLR2/6, with additional activation through the TLR2 homodimer. To expand the Toll-like receptor (TLR) activation profile of L. gasseri and the immunogenicity of the vector, a plasmid containing fliC, the gene encoding bacterial flagellin, was introduced which resulted in the strong activation of TLR5. The treatment of human myeloid dendritic cells with recombinant lactobacilli expressing flagellin triggered phenotypic maturation and the release of proinflammatory cytokines. In contrast, bacterial treatment also resulted in a statistically significant increase in IL-10 production. In vivo studies established that treatment with L. gasseri led to a diversification of B-cell populations in the lamina propria of the murine colon. Furthermore, treatment with genetically modified L. gasseri led to a significant decrease in the percentage of FoxP3 ؉ colonic lymphocytes. Taken together, these data clarify the interaction of L. gasseri with the host immune system and support further investigation of the in vivo immunogenicity of L. gasseri expressing both flagellin and candidate vaccine antigens.
Vaccines, 2021
Capsid-like particle (CLP) displays can be used to enhance the immunogenicity of vaccine antigens, but a better understanding of how CLP vaccines are best formulated and delivered is needed. This study compared the humoral immune responses in mice elicited against two different vaccine antigens (a bacterial protein and a viral peptide) delivered on an AP205 CLP platform using six different adjuvant formulations. In comparison to antibody responses obtained after immunization with the unadjuvanted CLP vaccine, three of the adjuvant systems (neutral liposomes/monophosphoryl lipid A/quillaja saponaria 21, squalene-in-water emulsion, and monophosphoryl lipid A) caused significantly increased antibody levels, whereas formulation with the three other adjuvants (aluminum hydroxide, cationic liposomes, and cationic microparticles) resulted in similar or even decreased antibody responses. When delivering the soluble bacterial protein in a squalene-in-water emulsion, 4-log lower IgG levels we...