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The gut commensal Anaerobutyricum soehngenii is an anaerobe that can produce both propionate and butyrate, metabolites that have been shown to have a positive effect on gut and overall health. Murine and human dose finding studies have shown that oral intake of A. soehngenii has a positive influence on peripheral insulin resistance, thereby reducing the risk of type 2 diabetes. A recent human intervention provided support for the mode of action of A. soehngenii as it affected gene expression in the duodenum, stimulated the secretion of GLP‐1 and improved insulin sensitivity. For these reasons A. soehngenii has been proposed as a food ingredient. Before introducing this bacterium to the food chain, however, it must be established that oral intake of live A. soehngenii bacteria does not pose any health risk. As part of the safety analysis of A. soehngenii strain CH106, we performed genotoxicity assays to determine its mutagenic potential (bacterial reverse mutation and in vitro mammalian cell micronucleus tests) and a 90‐day subchronic toxicity study in rats to determine overall toxicity potential. The results of both genotoxicity studies were negative, showing no genotoxic effects. For the 90‐day subchronic toxicity study, no adverse events were registered that could be attributed to the feeding with A. soehngenii strain CH106. Even at the highest dose, which exceeds the expected daily human intake more than 100‐fold, no adverse events were observed. These result support the conclusion that the use of A. soehngenii strain CH106 as a food ingredient is safe. Based on its health beneficial effects, the commensal bacterium Anaerobutyricum soehngenii strain CH106 is proposed as a food ingredient. As part of a safety assessment, toxic potential was tested through genotoxicity assays and a 90‐day subchronic toxicity study in rats. No genotoxic effects could be detected, while the rat study did not reveal any A. soehngenii‐related adverse events. The observations support the conclusion that the use of A. soehngenii strain CH106 as a food ingredient is safe. [ABSTRACT FROM AUTHOR]

Yersinia pestis, one of history's deadliest pathogens, has killed millions over the course of human history. It has attributes that make it an ideal choice to produce mass casualties and is a prime candidate for use as a biological weapon. When aerosolized, Y. pestis causes pneumonic plague, a pneumonia that is 100% lethal if not promptly treated with effective antibiotics. Currently, there is no FDA approved plague vaccine. The current lead vaccine candidate, a parenterally administered protein subunit vaccine comprised of the Y. pestis virulence factors, F1 and LcrV, demonstrated variable levels of protection in primate pneumonic plague models. As the most likely mode of exposure in biological attack with Y. pestis is by aerosol, this raises a question of whether this parenteral vaccine will adequately protect humans against pneumonic plague. In the present study we evaluated two distinct mucosal delivery platforms for the intranasal (IN) administration of LcrV and F1 vaccine proteins, a live bacterial vector, Lactobacillus plantarum, and a Tobacco Mosaic Virus (TMV) based delivery platform. IN administration of L. plantarum expressing LcrV, or TMV-conjugated to LcrV and F1 (TMV-LcrV+TMV-F1) resulted in the similar induction of high titers of IgG antibodies and evidence of proinflammatory cytokine secretion. However, only the TMV-conjugate delivery platform protected against subsequent lethal challenge with Y. pestis. TMV-LcrV+TMV-F1 co-vaccinated mice had no discernable morbidity and no mortality, while mice vaccinated with L. plantarum expressing LcrV or rLcrV+rF1 without TMV succumbed to infection or were only partially protected. Thus, TMV is a suitable mucosal delivery platform for an F1-LcrV subunit vaccine that induces complete protection against pneumonic infection with a lethal dose of Y. pestis in mice., Competing Interests: PMA, MS, CD, LAP, AM, and RD have no conflicts associated with this study., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Consumed for centuries, lactic acid bacteria are excellent candidates for the development of safe mucosal delivery vehicles for prophylactic and therapeutic molecules. We have recently reported that the immune response to an effective OspA-expressing L. plantarum vaccine for Lyme disease is modulated by the lipid modification of the antigen. In this study, we investigated if this technology can be applied to developing vaccines for other diseases by focusing on the Class A select agent, Yersinia pestis. We used a number of biochemistry and immunology techniques to determine the localization of the immunogen in our delivery vehicle and to evaluate the mucosal as well as the systemic immune response to the immunogen. We found that only LcrV cloned downstream of the signal sequence of B. burgdorferi OspA ((ss)LcrV), but not wildtype LcrV (LcrV), is localized to the desired peptidoglycan layer of the delivery vehicle. In addition, only mice that received L. plantarum expressing (ss)LcrV produced significant titers of IgG antibody as well as IgA in distant mucosal sites such as lungs and vagina. Furthermore, only L. plantarum expressing (ss)LcrV induced significant amounts of pro-inflammatory cytokines TNFα, IL-12, IFNγ and IL-6 as well as anti-inflammatory IL-10 in human peripheral blood mononuclear cells derived dendritic cells, suggesting that the mechanism by which LcrV-expressing L. plantarum stimulates the immune response involves polarization to Th1 mediated immunity with some involvement of Th2. The study reported here proves that this system is a platform technology to develop oral vaccines for multiple diseases., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Mucosal immunization is advantageous over other routes of antigen delivery because it can induce both mucosal and systemic immune responses. Our goal was to develop a mucosal delivery vehicle based on bacteria generally regarded as safe, such as Lactobacillus spp. In this study, we used the Lyme disease mouse model as a proof of concept. We demonstrate that an oral vaccine based on live recombinant Lactobacillus plantarum protects mice from tick-transmitted Borrelia burgdorferi infection. Our method of expressing vaccine antigens in L. plantarum induces both systemic and mucosal immunity after oral administration. This platform technology can be applied to design oral vaccine delivery vehicles against several microbial pathogens.

The genome of bacteriophage Tuc2009 consists of 38347 base pairs on which 57 open reading frames (ORFs) were identified, divided in two oppositely transcribed regions. The leftward-transcribed region harbors three ORFs, two of which are involved in the establishment of lysogeny. The rightward-transcribed region contains 54 ORFs, which are assumed to be required for the lytic life cycle. An exception to the above organization is ORF 10, of unknown function, located within the rightward-transcribed region that has an orientation opposite to the ORFs surrounding it. Transcriptional analysis of the Tuc2009 genome following infection of a sensitive host revealed that most ORFs are transcribed in a sequential manner. ORFs that are presumed to form (part of) the genetic switch along with the superinfection exclusion-encoding gene are transcribed immediately after infection, followed by transcription of the presumed replication region. Subsequent to this, several small transcripts could be identified followed by a single 24-kb transcript. This latter transcript was shown to specify most of the identified structural proteins as well as two proteins required for host lysis. Interestingly, the 24-kb mRNA was shown to undergo splicing through the activity of a type I intron whose removal from the mRNA resulted in the formation of an ORF specifying a major structural protein. Primer extension analysis was employed to identify the 5' ends of mRNA transcripts and the genome and transcriptional data are discussed in relation to other lactococcal bacteriophages.

Evidence is accumulating that lactobacilli influence the immune response in a strain-dependent manner. This immunomodulatory capacity is important for the development of the immune response, and also identifies Lactobacillus as a potent oral vaccine carrier. Most of our current knowledge of the use of lactobacilli for vaccination purposes has been obtained with tetanus toxin fragment C (TTFC) as the model antigen. This knowledge, together with our ever-increasing understanding of the immune system and recent developments in cloning and expression techniques, should enable the utilisation of antigens other than TTFC and has made the development of lactobacilli as live vaccines a realistic prospect.