Tularensis Subspecies Research Articles

A Synthetic Oligosaccharide Resembling Francisella tularensis Strain 15 O‐Antigen Capsular Polysaccharide as a Lead for Tularemia Diagnostics and Therapeutics

AbstractFrancisella tularensis, a category A bioterrorism agent, causes tularemia in many animal species. F. tularensis subspecies tularensis (type A) and holarctica (type B) are mainly responsible for human tularemia. The high mortality rate of 30–60 % caused by F. tularensis subspecies tularensis if left untreated and the aerosol dispersal renders this pathogen a dangerous bioagent. While a live attenuated vaccine strain (LVS) of F. tularensis type B does not provide sufficient protection against all forms of tularemia infections, a significant level of protection against F. tularensis has been observed for both passive and active immunization of mice with isolated O‐antigen capsular polysaccharide. Well‐defined, synthetic oligosaccharides offer an alternative approach towards the development of glycoconjugate vaccines. To identify diagnostics and therapeutics leads against tularemia, a collection of F. tularensis strain 15 O‐antigen capsular polysaccharide epitopes were chemically synthesized. Glycan microarrays containing synthetic glycans were used to analyze the sera of tularemia‐infected and non‐infected animals and revealed the presence of IgG antibodies against the glycans. Two disaccharide (13 and 18), both bearing a unique formamido moiety, were identified as minimal glycan epitopes for antibody binding. These epitopes are the starting point for the development of diagnostics and therapeutics against tularemia.

A Synthetic Oligosaccharide Resembling Francisella tularensis Strain 15 O-Antigen Capsular Polysaccharide as a Lead for Tularemia Diagnostics and Therapeutics.

Francisella tularensis, a category A bioterrorism agent, causes tularemia in many animal species. F. tularensis subspecies tularensis (type A) and holarctica (type B) are mainly responsible for human tularemia. The high mortality rate of 30-60% caused by F. tularensis subspecies tularensis if left untreated and the aerosol dispersal renders this pathogen a dangerous bioagent. While a live attenuated vaccine strain (LVS) of F. tularensis type B does not provide sufficient protection against all forms of tularemia infections, a significant level of protection against F. tularensis has been observed for both passive and active immunization of mice with isolated O-antigen capsular polysaccharide. Well-defined, synthetic oligosaccharides offer an alternative approach towards the development of glycoconjugate vaccines. To identify diagnostics and therapeutics leads against tularemia, a collection of F. tularensis strain 15 O-antigen capsular polysaccharide epitopes were chemically synthesized. Glycan microarrays containing synthetic glycans were used to analyze the sera of tularemia-infected and non-infected animals and revealed the presence of IgG antibodies against the glycans. Two disaccharide (13 and 18), both bearing a unique formamido moiety, were identified as minimal glycan epitopes for antibody binding. These epitopes are the starting point for the development of diagnostics and therapeutics against tularemia.

Strategies for tularemia pathogen survival, spread and virulence

The bacterium Francisella tularensis is the etiological agent of tularemia, a natural focal, especially dangerous infection, which, “thanks to” its low infectious dose and ability to be transmitted to humans via all possible routes, is a potential bioterrorism agent. This pathogen has been known to mankind for over a hundred years, but it is still impossible to prevent massive human disease outbreaks and sporadic incidence cases, whereas tularemia diagnosis may be verified within several days-to-weeks. The basis for tularemia causative agent virulence is based on its ability to disrupt phagocyte function. In animals and humans, the various Francisella tularensis systems work together to bypass host immune system, attach to and enter eukaryotic cells, block phagosome-lysosome fusion, multiply in various host cells without being detected, inhibit their destruction and cause host cell death to release bacteria and infect neighboring tissue cells, thus developing an infectious disease in different organs. This is achieved through a unique complement-dependent penetration process into host cell, called loop phagocytosis, and an unusual inert endotoxin as well as variation in diverse forms of “free” lipid A modifications and lipid A in the LPS composition, its dynamic acyl chain length regulation, and specifically combined regulatory factors to induce the “pathogenicity island” protein synthesis. Accumulated point mutations, intragenomic rearrangements, deletions, insertions, duplications, transpositions, gene degradation, variation in the number of copies in repeated DNA sequences, as well as homologous and non-homologous recombinations underlie a markedly expanded potential for existence of the tularemia causative agent: they contribute to the holarctic subspecies strain survival in varying conditions, including osmotic shock, to form multiple resistance to various toxic substances and alter F. tularensis subspecies virulence. Analyzing a whole body of publications on the abovementioned aspects for tularemia causative agent life activity attempts to combine the differences, structural features and “tricks” of the F. tularensis species cells allowing them to be a powerful pathogen, with a high potential to adapt upon low pathogen variability and a limited genome length compared with other specially dangerous bacteria.

Development, Strategies, and Challenges for Tularemia Vaccine.

Francisella tularensis is a facultative intracellular bacterial pathogen that affects both humans and animals. It was developed into a biological warfare weapon as a result. In this article, the current status of tularemia vaccine development is presented. A live-attenuated vaccine that was designed over 50years ago using the less virulent F. tularensis subspecies holarctica is the only prophylactic currently available, but it has not been approved for use in humans or animals. Other promising live, killed, and subunit vaccine candidates have recently been developed and tested in animal models. This study will investigate some possible vaccines and the challenges they face during development.

Functional characterization of Francisella tularensis subspecies holarctica genotypes during tick cell and macrophage infections using a proteogenomic approach.

Tularemia is a vector-borne disease caused by the Gram-negative bacterium Francisella tularensis. Known hosts and vectors in Europe are hare and ticks. F. tularensis is transmitted from ticks and animals, but also from the hydrotelluric environment and the consumption of contaminated water or food. A changing climate expands the range in which ticks can live and consequently might contribute to increasing case numbers of tularemia. Two subspecies of F. tularensis are human pathogenic. Francisella tularensis tularensis (Ftt) is endemic in North America, while Francisella tularensis holarctica (Fth) is the only subspecies causing tularemia in Europe. Ft is classified as a category A bioterrorism agent due to its low infectious dose, multiple modes of transmission, high infectivity and potential for airborne transmission and has become a global public health concern. In line with the European survey and previous phylogenetic studies, Switzerland shows the co-distribution of B.6 and B.12 strains with different geographical distribution and prevalence within the country. To establish itself in different host environments of ticks and mammals, F. tularensis presumably undergoes substantial changes on the transcriptomics and proteomic level. Here we investigate the transcriptomic and proteomic differences of five strains of Fth upon infection of rabbit macrophages and tick cells.

Mutation of wbtJ, a N-formyltransferase involved in O-antigen synthesis, results in biofilm formation, phase variation and attenuation in Francisella tularensis.

Two clinically important subspecies, Francisella tularensis subsp. tularensis (type A) and F. tularensis subsp. holarctica (type B) are responsible for most tularaemia cases, but these isolates typically form a weak biofilm under in vitro conditions. Phase variation of the F. tularensis lipopolysaccharide (LPS) has been reported in these subspecies, but the role of variation is unclear as LPS is crucial for virulence. We previously demonstrated that a subpopulation of LPS variants can constitutively form a robust biofilm in vitro, but it is unclear whether virulence was affected. In this study, we show that biofilm-forming variants of both fully virulent F. tularensis subspecies were highly attenuated in the murine tularaemia model by multiple challenge routes. Genomic sequencing was performed on these strains, which revealed that all biofilm-forming variants contained a lesion within the wbtJ gene, a formyltransferase involved in O-antigen synthesis. A ΔwbtJ deletion mutant recapitulated the biofilm, O-antigen and virulence phenotypes observed in natural variants and could be rescued through complementation with a functional wbtJ gene. Since the spontaneously derived biofilm-forming isolates in this study were a subpopulation of natural variants, reversion events to the wbtJ gene were detected that eliminated the phenotypes associated with biofilm variants and restored virulence. These results demonstrate a role for WbtJ in biofilm formation, LPS variation and virulence of F. tularensis.

Three Cases of Tickborne Francisella tularensis Infection, Austria, 2022.

Tularemia is increasing in Austria. We report Francisella tularensis subspecies holarctica isolated from 3 patients who had been bitten by arthropods. Next-generation sequencing showed substantial isolate similarity. Clinicians should consider bloodstream F. tularensis infections for patients with signs/symptoms of ulceroglandular tularemia, and surveillance of potential vectors should be intensified.

Tularemia – a re-emerging disease with growing concern

Tularemia caused by Gram-negative, coccobacillus bacterium, Francisella tularensis, is a highly infectious zoonotic disease. Human cases have been reported mainly from the United States, Nordic countries like Sweden and Finland, and some European and Asian countries. Naturally, the disease occurs in several vertebrates, particularly lagomorphs. Type A (subspecies tularensis) is more virulent and causes disease mainly in North America; type B (subspecies holarctica) is widespread, while subspecies mediasiatica is present in central Asia. F. tularensis is a possible bioweapon due to its lethality, low infectious dosage, and aerosol transmission. Small mammals like rabbits, hares, and muskrats are primary sources of human infections, but true reservoir of F. tularensis is unknown. Vector-borne tularemia primarily involves ticks and mosquitoes. The bacterial subspecies involved and mode of transmission determine the clinical picture. Early signs are flu-like illnesses that may evolve into different clinical forms of tularemia that may or may not include lymphadenopathy. Ulcero-glandular and glandular forms are acquired by arthropod bite or handling of infected animals, oculo-glandular form as a result of conjunctival infection, and oro-pharyngeal form by intake of contaminated food or water. Pulmonary form appears after inhalation of bacteria. Typhoidal form may occur after infection via different routes. Human-to-human transmission has not been known. Diagnosis can be achieved by serology, bacterial culture, and molecular methods. Treatment for tularemia typically entails use of quinolones, tetracyclines, or aminoglycosides. Preventive measures are necessary to avoid infection although difficult to implement. Research is underway for the development of effective live attenuated and subunit vaccines.

Human Tularemia Epididymo-Orchitis Caused by Francisella tularensis Subspecies holartica, Austria.

A previously healthy man in Austria had tularemia epididymo-orchitis develop, leading to unilateral orchiectomy. Francisella tularensis subspecies holartica was detected by 16S rRNA gene sequencing analysis of inflamed granulomatous testicular tissue. Clinicians should suspect F. tularensis as a rare etiologic microorganism in epididymo-orchitis patients with relevant risk factors.

Ceftobiprole Medocaril Is an Effective Post-Exposure Treatment in the Fischer 344 Rat Model of Pneumonic Tularemia.

Francisella tularensis subspecies tularensis is a category-A biothreat agent that can cause lethal tularemia. Ceftobiprole medocaril is being explored as a medical countermeasure for the treatment of pneumonic tularemia. The efficacy of ceftobiprole medocaril against inhalational tularemia was evaluated in the Fischer 344 rat model of infection. The dose was expected to be effective against F. tularensis isolates with ceftobiprole minimum inhibitory concentrations ≤0.5 µg/mL. Animals treated with ceftobiprole medocaril exhibited a 92% survival rate 31 days post-challenge, identical to the survival of levofloxacin-treated rats. By comparison, rats receiving placebo experienced 100% mortality. Terminally collected blood, liver, lung, and spleen samples confirmed disseminated F. tularensis infections in most animals that died prior to completing treatments (placebo animals and a rat treated with ceftobiprole medocaril), although levels of bacteria detected in the placebo samples were significantly elevated compared to the ceftobiprole-medocaril-treated group geometric mean. Furthermore, no evidence of infection was detected in any rat that completed ceftobiprole medocaril or levofloxacin treatment and survived to the end of the post-treatment observation period. Overall, survival rates, body weights, and bacterial burdens consistently demonstrated that treatment with ceftobiprole medocaril is efficacious against otherwise fatal cases of pneumonic tularemia in the rat model.

Case Studies and Literature Review of Francisella tularensis–Related Prosthetic Joint Infection

Tularemia is a zoonotic infection caused by Francisella tularensis. Its most typical manifestations in humans are ulceroglandular and glandular; infections in prosthetic joints are rare. We report 3 cases of F. tularensis subspecies holarctica-related prosthetic joint infection that occurred in France during 2016-2019. We also reviewed relevant literature and found only 5 other cases of Francisella-related prosthetic joint infections worldwide, which we summarized. Among those 8 patients, clinical symptoms appeared 7 days to 19 years after the joint placement and were nonspecific to tularemia. Although positive cultures are typically obtained in only 10% of tularemia cases, strains grew in all 8 of the patients. F. tularensis was initially identified in 2 patients by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry; molecular methods were used for 6 patients. Surgical treatment in conjunction with long-term antimicrobial treatment resulted in favorable outcomes; no relapses were seen after 6 months of follow-up.

Intraspecific Differentiation of <i>Francisella tularensis</i> Strains Using Multilocus Real-Time Polymerase Chain Reaction

The aim of the study was to develop a method for intraspecific differentiation of the tularemia microbe: subspecies tularensis (subpopulations AI and AII), holarctica (biovars japonica, EryS/R), mediasiatica, and novicida using multilocus real-time PCR. Materials and methods. We used 48 strains of F. tularensis of various subspecies, biovars, and subpopulations. Intraspecific appurtenance of the strains was carried out on the basis of the analysis of the RD-1 region variability applying PCR, the sdhA gene by Sanger fragment sequencing and by the disk diffusion method using disks with erythromycin. The selection of primers and probes was performed using the software available at www.genscript.com and GeneRunner 6.5.52. Sequence homology was assessed using the BLAST algorithm and the GenBank NCBI database. Results and discussion. New data on the structure and occurrence of the differentiation regions RD-8, RD-12, RD-28 of FTT1122c gene and its homologous sequences in strains of tularemia microbe of various subspecies have been obtained. Novel RDhm 346 bp in size, characteristic of strains of the subsp. mediasiatica, holarctica, which is deleted in subsp. tularensis and absent in subsp. novicida has been detected. Based on the detection of the FTT1670, FTT1122с, FTT1067, FTW_2084 loci, a multilocus real-time PCR has been developed – “F. tularensis 4c”, providing for identification of all subspecies of the tularemia microbe, separately for the biovar japonica of the Holarctic subspecies and subpopulations AI, AII of the subspecies tularensis. The PCR specificity was confirmed in the study of strains of tularemia microbe from the fund of the “State Collection of Pathogenic Bacteria” at the premises of the Russian Reserarch Anti-Plague Institute “Microbe”. The results obtained expand the concept of intraspecific genetic heterogeneity of tularemia microbe and possibilities of identifying the causative agent of tularemia using molecular-genetic methods. They are important for understanding the processes of adaptation of the pathogen to circulation in the host organism and environmental objects, the course of evolution and formation of new species of Francisella.

ANATOMY OF THE IMMUNE RESPONSE TO FRANCISELLA TULARENSISLVS INFECTION IN THE LUNGS.

Abstract The respiratory mucosa is under constant immune surveillance because of its vulnerability to infectious diseases. Infection of the lungs with the live vaccine strain (LVS) derived from Francisella tularensis (Ft) subspecies holarctica models pulmonary tularaemia-like disease in mice. Current evidence suggest many immune cells and cytokines respond to Ft LVS infection, but how these various immune system components are integrated to mount a protective response remains unclear. Hence, in a transcriptomics study at single cell resolution, we characterized the acute immune landscape in the lungs of C57BL/6 mice at day 0 and day 7 post intranasal inoculation with Ft LVS. Defining features of the immune response include a robust type 1 immune response characterized by the accumulation of inflammatory neutrophils and the expansion of innate-like effector lymphocytes, primarily interferon-γ producing NKT1, NK, and effector CD8 +T cells. Increased accumulation of MAIT17 over MAIT1 cells is another feature, which is in line with previous findings linking MAIT cells and IL-17 to LVS immune response. Surprisingly, a significant proportion of MAIT17 cells either maintained or upregulated type 1 inflammatory markers. Similarly, MAIT1 cells maintained or upregulated Type 3 inflammatory markers. Additionally, a highly active MAIT cell subset has increased Nr4a1 expression, which encodes Nur77, suggesting a T cell receptor-mediated activation. By contrast, NKT1 cells poorly upregulated Nr4a1 expression but induced Il18r1 expression suggesting, a cytokine-mediated activation. Consequently, we predict that unconventional NKT & MAIT cells integrate innate cues to control tularaemia-like disease caused by Ft LVS infection in the mouse. VUSM MSTP NIGMS of the National Institutes of Health T32GM007347 (GDO); IO1 BX001444, BX001610, BX00xxx, IK6 BX004595 & RO1 AI137082; IBX000915A (HMA)

Identification of Francisella tularensis Subspecies in a Clinical Setting Using MALDI-TOF MS: An In-House Francisella Library and Biomarkers.

Francisella tularensis is a zoonotic bacterium that is endemic in large parts of the world. It is absent in the standard library of the most applied matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) systems: the Vitek MS and the Bruker Biotyper system. The additional Bruker MALDI Biotyper Security library contains F. tularensis without subspecies differentiation. The virulence of F. tularensis differs between the subspecies. The F. tularensis subspecies (ssp.) tularensis is highly pathogenic, whereas the subspecies holarctica displays lower virulence and subspecies novicida and F. tularensis ssp. mediasiatica are hardly virulent. To differentiate the Francisellaceae and the F. tularensis-subspecies, an in-house Francisella library was built with the Bruker Biotyper system and validated together with the existing Bruker databases. In addition, specific biomarkers were defined based on the main spectra of the Francisella strains supplemented with in silico genome data. Our in-house Francisella library accurately differentiates the F. tularensis subspecies and the other Francisellaceae. The biomarkers correctly differentiate the various species within the genus Francisella and the F. tularensis subspecies. These MALDI-TOF MS strategies can successfully be applied in a clinical laboratory setting as a fast and specific method to identify F. tularensis to subspecies level.

Contribution of Lipid Mediators in Divergent Outcomes following Acute Bacterial and Viral Lung Infections in the Obese Host.

Obesity is considered an important comorbidity for a range of noninfectious and infectious disease states including those that originate in the lung, yet the mechanisms that contribute to this susceptibility are not well defined. In this study, we used the diet-induced obesity (DIO) mouse model and two models of acute pulmonary infection, Francisella tularensis subspecies tularensis strain SchuS4 and SARS-CoV-2, to uncover the contribution of obesity in bacterial and viral disease. Whereas DIO mice were more resistant to infection with SchuS4, DIO animals were more susceptible to SARS-CoV-2 infection compared with regular weight mice. In both models, neither survival nor morbidity correlated with differences in pathogen load, overall cellularity, or influx of inflammatory cells in target organs of DIO and regular weight animals. Increased susceptibility was also not associated with exacerbated production of cytokines and chemokines in either model. Rather, we observed pathogen-specific dysregulation of the host lipidome that was associated with vulnerability to infection. Inhibition of specific pathways required for generation of lipid mediators reversed resistance to both bacterial and viral infection. Taken together, our data demonstrate disparity among obese individuals for control of lethal bacterial and viral infection and suggest that dysregulation of the host lipidome contributes to increased susceptibility to viral infection in the obese host.

Arginine Catabolism and Polyamine Biosynthesis Pathway Disparities Within Francisella tularensis Subpopulations.

Francisella tularensis is a highly infectious zoonotic pathogen with as few as 10 organisms causing tularemia, a disease that is fatal if untreated. Although F. tularensis subspecies tularensis (type A) and subspecies holarctica (type B) share over 99.5% average nucleotide identity, notable differences exist in genomic organization and pathogenicity. The type A clade has been further divided into subtypes A.I and A.II, with A.I strains being recognized as some of the most virulent bacterial pathogens known. In this study, we report on major disparities that exist between the F. tularensis subpopulations in arginine catabolism and subsequent polyamine biosynthesis. The genes involved in these pathways include the speHEA and aguAB operons, along with metK. In the hypervirulent F. tularensis A.I clade, such as the A.I prototype strain SCHU S4, these genes were found to be intact and highly transcribed. In contrast, both subtype A.II and type B strains have a truncated speA gene, while the type B clade also has a disrupted aguA and truncated aguB. Ablation of the chromosomal speE gene that encodes a spermidine synthase reduced subtype A.I SCHU S4 growth rate, whereas the growth rate of type B LVS was enhanced. These results demonstrate that spermine synthase SpeE promotes faster replication in the F. tularensis A.I clade, whereas type B strains do not rely on this enzyme for in vitro fitness. Our ongoing studies on amino acid and polyamine flux within hypervirulent A.I strains should provide a better understanding of the factors that contribute to F. tularensis pathogenicity.

Differentiation of the Francsella tularensis subspecies by the INDEL typing method

Background. Francisella tularensis, the etiological agent of tularemia, belongs to the facultative intracellular pathogens that cause severe disease in humans and man species of animals, and is a category A bioterrorism agent. Currently, F. tularensis is divided into four subspecies: F. tularensis subsp. tularensis (nearctica), F. tularensis subsp. holarctica, F. tularensis subsp. mediasiatica, F. tularensis subsp novicida, which differ in their pathogenicity and geographical distribution. Historically, this division was due to the different distribution area of strains, their differences in biochemical activity and pathogenicity for different hosts. The biochemical identification of subspecies is very laborious and requires work with live cultures of the microorganism, which determines the need to develop new molecular genetic approaches for genotyping F. tularensis strains.The aim of this study is to develop a method for differentiating subspecies and individual groups of F. tularensis based on INDEL typing. Research objectives: creation of a local database of nucleotide sequences of F. tularensis strains of different subspecies, search for INDEL markers that are significant for the differentiation of subspecies of the causative agent of tularemia, designing primers for the detection of INDEL markers using PCR, optimization of the set of INDEL markers and elucidation of phylogenetic relationships between the studied strains based on the proposed INDEL typing method.Materials and methods. The local database of nucleotide sequences of F. tularensis strains of different subspecies for comparative analysis of F. tularensis genomes presented in the GenBank database was created using the author's software. Detection of INDEL markers in the genomes of strains of the local database was carried out using the GeneExpert program. Primer design and in silico PCR were performed using the Primer3Plus software and the proprietary VirtualPCR software. Cluster analysis and construction of a phylogenetic tree were performed using the GrapeTree program.Results and discussion. The implementation of the proposed five INDEL markers for genotyping of 29 studied strains of different subspecies from the GenBank database made it possible to detect 9 individual genotypes with a high diversity index (DI = 0.85). Not only the corresponding division of the tularensis, holarctica, mediasiatica, and novicida subspecies into different clusters was noted, but also the intraspecific division into groups of strains was observed. Differentiation of F. tularensis subspecies was confirmed in vitro for the collection of strains of different subspecies of the Collection of Living Cultures of the Rostov-on-Don Plague Control Researsh Institute.Conclusion. For the first time, the F. tularensis subspecies differentiation system based on the INDEL typing method has been developed, which allows in vitro identification of both F. tularensis subspecies (tularensis, holarctica, mediasiatica and novicida) and groups of strains within subspecies without the need for strain sequencing. The method is protected by a patent. The topology of the INDEL phylogenetic tree of genotypes of F. tularensis strains correlates with the patterns of evolution of the tularemia microbe presented earlier. The proposed method can be used for combined typing of F. tularensis strains together with MLVA or SNP typing

Tularemia Transmission to Humans, the Netherlands, 2011-2021.

We used national registry data on human cases of Francisella tularensis subspecies holarctica infection to assess transmission modes among all 26 autochthonous cases in the Netherlands since 2011. The results indicate predominance of terrestrial over aquatic animal transmission sources. We recommend targeting disease-risk communication toward hunters, recreationists, and outdoor professionals.

Alginate microencapsulation of an attenuated O-antigen mutant of Francisella tularensis LVS as a model for a vaccine delivery vehicle.

Francisella tularensis is the etiologic agent of tularemia and a Tier I Select Agent. Subspecies tularensis (Type A) is the most virulent of the four subspecies and inhalation of as few as 10 cells can cause severe disease in humans. Due to its niche as a facultative intracellular pathogen, a successful tularemia vaccine must induce a robust cellular immune response, which is best achieved by a live, attenuated strain. F. tularensis strains lacking lipopolysaccharide (LPS) O-antigen are highly attenuated, but do not persist in the host long enough to induce protective immunity. Increasing the persistence of an O-antigen mutant may help stimulate protective immunity. Alginate encapsulation is frequently used with probiotics to increase persistence of bacteria within the gastrointestinal system, and was used to encapsulate the highly attenuated LVS O-antigen mutant WbtIG191V. Encapsulation with alginate followed by a poly-L-lysine/alginate coating increased survival of WbtIG191V in complement-active serum. In addition, BALB/c mice immunized intraperitoneally with encapsulated WbtIG191V combined with purified LPS survived longer than mock-immunized mice following intranasal challenge. Alginate encapsulation of the bacteria also increased antibody titers compared to non-encapsulated bacteria. These data suggest that alginate encapsulation provides a slow-release vehicle for bacterial deposits, as evidenced by the increased antibody titer and increased persistence in serum compared to freely suspended cells. Survival of mice against high-dose intranasal challenge with the LVS wildtype was similar between mice immunized within alginate capsules or with LVS, possibly due to the low number of animals used, but bacterial loads in the liver and spleen were the lowest in mice immunized with WbtIG191V and LPS in beads. However, an analysis of the immune response of surviving mice indicated that those vaccinated with the alginate vehicle upregulated cell-mediated immune pathways to a lesser extent than LVS-vaccinated mice. In summary, this vehicle, as formulated, may be more effective for pathogens that require predominately antibody-mediated immunity.

Molecular-Genetic Bases of Differences between Tularaemia Pathogen Subspecies and Francisella tularensis subsp. holarctica Strain Typing

Molecular-Genetic Bases of Differences between Tularaemia Pathogen Subspecies and Francisella tularensis subsp. holarctica Strain Typing