A treatment strategy for cancer is the suppression of tumor growth by directing an immune response to the tumor vessels, which will destroy the tissue. In this thesis we describe the development of a vaccine that targets antigens expressed around angiogenic vasculature in most solid tumors. These antigens are alternative spliced extra domains of glycoproteins present in the extracellular matrix; e.g. the extra domain-B (ED-B) and extra domain-A (ED-A) of fibronectin and the C-domain of tenascin-C (TNCC). We show that it is possible to break self-tolerance and induce a strong antibody response against ED-B by vaccination. Furthermore, tumor growth was inhibited and the changes observed in the tumor tissue were consistent with an attack of the tumor vasculature by the immune system. For clinical development of therapeutic vaccines, targeting self-molecules like ED-B, a potent but non-toxic biodegradable adjuvant is required. The squalene-based Montanide ISA 720 (M720) in combination with CpG DNA fulfilled these requirements and induced an equally strong anti-self immune response as the preclinical golden standard Freund’s adjuvant. We have further characterized the immune response against ED-B generated with the adjuvant M720/GpG.  The ED-B vaccine also inhibited tumor growth in a therapeutic setting in a transgenic mouse model of pancreatic insulinoma in which tumorigenesis was already initiated. Furthermore, antibodies against ED-A and TNCC could be induced in mice and rabbits. We analyzed the expression of ED-A in breast tumors of transgenic MMTV-PyMT mice, a metastatic breast cancer model, with the aim to use this model to study the effect of an ED-A vaccine on metastasis. We also detected ED-B in canine mammary tumor tissue. Therefore vascular antigens might also represent potential therapeutic targets in dogs.  All together our preclinical data demonstrate that a vaccine targeting tumor blood vessels is a promising new approach for cancer treatment.

New efficient vaccines against infectious diseases are in demand. Some important factors impeding the vaccine development are the poor immunogenicity and the MHC restriction of the immune responses to a number of antigens. The use of novel vaccine adjuvants or carrier proteins, which are known to enhance the immunogenicity of the subunit antigens and provide T-cell help, can circumvent these problems. The potential of heat shock proteins (HSPs) to function as adjuvants when fused to or co-delivered with protein antigens, make them attractive vaccine candidates. In this thesis we have evaluated the potency of heat shock protein 70 (HSP70) as a possible vaccine adjuvant and studied the mechanisms behind the adjuvanticity. The first article aims to evaluate the carrier effect of glutathione-S-transferase (GST) on a malarial antigen EB200 that induces a MHC restricted response in mice. Immunization of CBA and C57BL/6 mice, high and low responders to EB200, respectively, with the GST-EB200 fusion protein elicited EB200 specific antibody responses in both strains of mice, which indicated that MHC restriction was broken in C57BL/6 mice. However, the antibody affinity and the magnitude of the response were lower in the C57BL/6 mice compared with that in CBA. To improve the response, the efficacy of various adjuvants like alum, HSP70 from Trypanosoma cruzi, and the adjuvant combination (HSP70 and cholera toxin) was evaluated. The results indicated that cholera toxin and HSP70 act synergistically and improve the immunogenicity of EB200 antigen by increasing the affinity and magnitude of the response. HSP belongs to a family of conserved molecules and the maximum homology lies on the N-terminal region of the protein, therefore there is a risk that use of a complete molecule would give rise to autoimmunity. Thus, in our second study we first evaluated the adjuvant effect of the less conserved portion of HSP70 derived from Plasmodium falciparum (Pf70C). We found that the Pf70C exhibited similar adjuvant properties as the whole molecule. We further analyzed the adjuvant potential of Pf70C against EB200 formulated as a chimeric DNA vaccine construct. These constructs alone failed to generate substantial levels of EB200 specific antibodies in mice. However, the DNA immunization efficiently primed the immune system. This was evident as the subsequent boosting with the corresponding recombinant fusion proteins Pf70C-EB200 elicited strong EB200 specific Th-1 antibody responses. In contrast, no such priming effect was observed for ex vivo IFN-γ production, however stimulation with the Pf70C-EB200 fusion protein induced an enhanced secretion of IFN-γ in vitro. During the infection process, the synthesis of bacterial HSP is up-regulated, which is known to sensitize T cells in the infected host. Since a high degree of homology exists within the phylogenetic families of HSPs, we postulated that exposure of mice to microorganisms could prime the immune system for evolutionary diverse HSPs and for any antigen coupled to them. We tested this hypothesis by priming mice with different microorganisms such as BCG, Mycobacterium vaccae or Chlamydia pneumoniae and boosted with a recombinant fusion protein Pf70C-EB200 or with a panel of HSPs. We found that BCG and M. vaccae but not C. pneumoniae could provide priming of the immune system to induce secondary IgG responses to Pf70C as well as to other HSPs tested. The priming effect was also observed when the EB200 antigen was coupled to Pf70C. Analysis of the IgG1 and IgG2a profiles and IFN-g production induced against the HSPs revealed a mixture of Th1/Th2 type of responses. We also observed that HSP70 specific sera cross-reacted some extent with certain autoreactive antigens. However, no deposits were observed in the kidneys of HSP treated animals. Finally, we investigated the role of TLR2 and TLR4 on HSP70-mediated adjuvanticity. We found that HSPs displayed different degrees of adjuvanticity regarding both the strength and the profile of the induced immune response. Also, they possessed different requirements for signaling through TLRs. While HSP70 from T. cruzi induced antigen-specific humoral responses in wild type as well as in both the TLR2 and TLR4 knockout mice, the response was diminished in the TLR4 knockout mice when both the whole and C-terminal fragment of HSP70 from Mycobacterium tuberculosis was used. However, the C-terminal fragment of P. falciparum HSP70 elicited responses only in wild type mice but not in TLR2 or TLR4 knockout mice indicating that the adjuvant function differ for phylogenetically related HSPs. Taken together our data suggest that HSPs can be promising candidates in future vaccines.

Cancer vaccines can fail despite the induction of large numbers of CD8+ T cells. Two categories of memory CD8+ T cells have been defined; central memory (TCM, IL-7RαhighCD44highCD62Lhigh) and effector memory (TEM, IL-7RαhighCD44highCD62Llow). It is clear that the memory phenotype of CD8+ T cells can affect vaccine potential; however methods to augment a beneficial phenotype are not clear. I have compared three vaccine delivery systems: Listeria monocytogenes, Salmonella enterica serovar Typhimurium and the particulate liposomal adjuvant, archaeosomes, for their efficacy to protect against murine melanoma. My study revealed that the anti-tumour response is strongly influenced by the kinetics, phenotype, and lymph node homing potential of CD8+ T cells. Listeria monocytogenes-ovalbumin (LM-OVA) induced TCM cells were adept at long lasting protection against B16-OVA melanoma due to their increased homeostatic and antigen-induced proliferation, interleukin-2 production, and ability to extravasate into tumour draining lymph nodes. Conversely, although Salmonella Typhimurium-ovalbumin (ST-OVA) induced TEM, produced IFN-γ, and killed target cells, this was insufficient for long-term tumour protection. Selectin-ligand engagements of TCM cells influenced their homing potential and efficacy against murine melanoma. Fucosyltransferase deficient (FtDKO) mice, lacking functional selectin ligands, were vaccinated with LM-OVA; despite the activation of cytotoxic CD8+ T cells, there was a reduced protection against murine melanoma compared to wild-type. FtDKO CD8+ T cells exhibited reduced extravasation into FtDKO lymph nodes compared to wild-type. Additionally, fewer FtDKO CD8+ T cells compared to wild-type migrated into tumour sites. Archaeosome vaccination was used to compare the influence of CD8+ T cell quantity versus phenotype. Single or multiple therapeutic vaccinations with archaeosome-OVA yielded transient melanoma tumour protection, despite an increased frequency of circulating and tumour infiltrating CD8+ T cells. This correlated with increased expression of Program death receptor-1 (PD-1) on CD8+ T cells and induction of regulatory T cells. Prophylactic archaeosome-OVA vaccination resulted in a maximal frequency of antigen-specific CD8+ T cells of ~50-60 % with just three injections, and ~50 % of the mice were of mice were afforded long-term tumour protection (> 90 days). Overall, my study shows that the choice of vaccine adjuvant and/or vector can profoundly influence CD8+ T cell quality and cancer vaccine efficacy.

This thesis examined the evidence, policy decision-making, and implementation of HPV vaccination in Canada as a case study to explore normalization versus individualized decision making in public health programs. Mixed methods were used: a systematic review, content analyses and policy document analysis. Overall, the scientific evidence supported an effect of vaccination against HPV infection and precancerous cervical lesions, but evidence regarding cervical cancer incidence or mortality is lacking. Scientific and medical communities appeared optimistic about the vaccine, but cautious about its readiness for routine implementation. Policy decision-making was initially cautious, but shifted towards active program implementation, possibly related to the availability of federal funding. The educational materials and media coverage both sent clearly normalizing messages about HPV vaccination. The discussion suggests that HPV vaccination might be more suited to an individualized than population approach, but many factors coincided to promote its implementation, in Canada, within a traditional public health model.

Taenia solium is a cestode that has a two-hosts life cycle. The adult tapeworm causes an asymptomatic disease known as taeniasis whereas the larval stage causes a disease called cysticercosis. In humans, the most common localization for the larvae is the central nervous system where it produces the neurological disorder neurocysticerco-sis. Previous works by several research groups around the world have shown that T. so-lium is a potentially eradicable parasite. Control programs have included treatment of human and pig populations with antihelmintics in conjunction with health education and are now considering vaccination of naïve piglets. The potential of a live vector vaccine system to deliver Taenia solium Tsol18, a proven protective antigen, to prevent transmission of cysticercosis was investigated. An attenuated strain of Salmonella enterica serovar Typhimurium χ9402 was used to develop an oral delivery system. Tsol18 gene was cloned downstream from the β-lactamase signal sequence in a multicopy asd + plasmid vector pYA3620 to yield plasmid pYA3620/Tsol18 and then transformed into the vaccine strain. The recombinant atte-nuated salmonella vaccine construct was stable for 50 generations and expressed rTsol18. Immunization of mice either with one or two doses of 109 CFU of the recombi-nant vaccine strain carrying plasmid pYA3620/Tsol18 elicited specific antibody response to Salmonella self antigens and to rTsol18. Moreover, oral immunization of piglets with 1012 CFU of the vaccine construction significantly reduced the numbers of viable cysts after challenged. The development of a quantitative assay to detect specific antibodies against Tsol18 is also presented here. The Falcon assay screening test –enzyme linked immu-noabsorbant assay (FAST-ELISA) format was used to develop a quantitative antibody detection assay. We have cloned, expressed and purified rTsol18. With purified porcine IgGs we constructed a standard curve that can be used to quantify the immune re-sponse. Our Fast-ELISA was able to follow the kinetics of the immune response in vac-cinated pigs from an experimental trial. The data we present here provides the basis for a safe, affordable and easy vaccine delivery system that can be used as an adjunct in control programs.

The Shiga-like toxins have DNA sequence homology to the toxins accountable for the dysentery brought about by the Shigella species. <i>Escherichia coli</i> which encode and produce shiga-like toxins are referred to as shiga toxin-producing E. coli (STEC). Upon infection with STEC, humans may develop a variety of clinical symptoms ranging in severity from bloody diarrhea to life threatening hemolytic uremic syndrome (HUS). Hemolytic uremic syndrome is the most fatal disease manifestation upon STEC infection for humans and has been documented to occur in up to 20% of patients upon STEC infection [29]. The Shiga toxins (Shiga toxin 1 and 2) are regarded as the principal virulence factor of STEC and are responsible for the clinical manifestations during HUS in humans [49].<p> Cattle are the primary non-human reservoir for STEC and therefore represent an attractive target for pre-slaughter intervention as a means to reduce human infections. To date, vaccination with secreted proteins including Shiga toxin 2 (Stx2), has reduced the numbers of bacteria shed in feces [3]. Even though published data exists supporting vaccination in cattle as a means to reduce STEC, commercially available vaccines are not being used by farms and STEC remain a significant zoonotic pathogen of humans causing disease and death. To further our knowledge about STEC pathogenesis in cattle, we examined the effect of Shiga toxin 2 on bovine immune responses. Bovine lymphocyte function was determined in the presence of Shiga toxin 2 and the magnitude of bovine immunological responses was measure after immunization with Shiga toxin 2. In general, results suggest that Shiga toxin 2 downregulates bovine immune responses suggesting vaccination with effector molecules that exclude Shiga toxin 2 may induce a better immunological response and improve vaccine efficacy.<p> To examine the possibility that Stx2 modulates bovine immune responses, we investigated lymphocyte function in the presence of Stx2. Menge et al [70] have reported that bovine lymphocytes express the Stx receptor and that Shiga toxin 1 inhibits lymphocyte proliferation in vitro. We isolated two populations of lymphocytes, peripheral blood mononuclear cells (PBMCs) and ileal Peyers patch lymphocytes (IPPL) and compared lymphocyte function in the presence and absence of Stx2. We found that Stx2 did not affect IPPL viability in vitro but did inhibit IPPL proliferation after 12 hours of incubation <i>in vitro</i>. In contrast, no altered PBMC function could be observed in the presence of Stx2. These results suggest that receptor-bound Stx2 may inhibit IPPL proliferation and that the two populations of lymphocytes isolated are unique and distinct from each other in their response to Stx2.<p> To determine the effect of Stx2 on bovine immune responses during STEC infection, a bovine ileal ligated loop model was employed. Ligated loops were inoculated with either a Stx2+ STEC strain or an isogenic Stx2- STEC strain. After 24 hours, IPPL populations were isolated from each ligated loop and immunophenotyped. The results indicated a significantly reduced CD4+ T cell population in the presence of Stx2. No differences in the levels of IFNá, TNFá, IL12 or IFNã could be detected between groups. These results suggest that Stx2 modulates bovine immune responses but not as a result of increased production of these cytokines. To extend this finding, we determined the effect of Stx2 on bovine immune responses during active immunization by using ELISA to measure serological responses in the presence and absence of Stx2. Serological responses to secreted proteins, as well as a co-administered antigen (hen egg lysozyme), were significantly reduced in the groups of cattle that were immunized with either purified Stx2 or secreted protein preparations isolated from STEC compared to groups vaccinated with antigens which did not contain the toxin. Bovine proliferative responses were also measured and the results indicated significantly reduced proliferation in the groups vaccinated with the formulations containing Stx2. Therefore, based on these results, we conclude that Stx2 downregulates bovine immune responses and thus may contribute to the colonization and persistence of cattle by STEC.

As respiratory syncytial virus (RSV) is a respiratory pathogen that causes significant morbidity and mortality in infants, there has always been great interest in the development of a vaccine. In the 1960s, children were immunized with formalin-inactivated (FI)-RSV vaccines. Not only did these vaccines fail to prevent infection, but in most cases they resulted in enhanced disease upon subsequent exposure to the virus. In the intervening years, studies in mice have led to the hypothesis that the enhanced disease is due to an aberrant Th2-biased immune response. Thus, we hypothesized that formulating FI-RSV vaccines with a Th1 promoting adjuvant, such as CpG oligoeoxynucleotides (ODN), would result in the induction of protective immunity against RSV without risk of deleterious effects. We observed in calves that parenterally delivered FI-bovine RSV (BRSV) formulated with CpG ODN resulted in a shift towards a Th1-biased or more balanced immune response that was protective against BRSV.<p> As RSV infects the lung mucosa, vaccines that induce mucosal immunity are desirable. Parenterally delivered vaccines typically induce systemic immunity with low mucosal immune response levels, whereas mucosally delivered vaccines induce systemic and mucosal immunity. However, upon mucosal delivery there is an increased chance of vaccine components being degraded or washed away prior to the induction of immunity. Thus, we added polyphosphazenes (PP) to our mucosal vaccine formulations. PP are synthetic polymers that form non-covalent complexes with other vaccine components, increasing their stability. Intranasally delivered FI-BRSV co-formulated with CpG ODN and PP performed better than FI-BRSV alone, or FI-BRSV formulated with either adjuvant individually, in terms of inducing protective immunity against BRSV in mice. Furthermore, mice that received intranasally-delivered FI-BRSV or BRSV F protein co-formulated with CpG ODN and PP developed higher levels of immunity and protection than mice that received parenterally delivered vaccines. Because of the similarities between BRSV and HRSV, co-formulation of intranasally delivered HRSV vaccines with CpG ODN and PP could prove important in the development of a safe vaccine against HRSV in humans.

This thesis describes the West Nile virus (WNV) epidemic in horses by exploring all aspects: sub-clinical infection, development of clinical disease and case fatality. All of the collected data were then compiled to create predictive risk maps of WNV infection for the province of Saskatchewan. <p>During the 2003 season, 133 clinical cases were documented with laboratory testing. Week of onset of clinical signs, gender, and coat color were significant predictors of whether the horse died or was euthanized due to severity of clinical signs. Studies of the serological response to vaccination and natural infection were examined to interpret the lab results from over 1100 samples taken from approximately 875 horses in 2003. A serologic study involving 212 horses on 20 farms determined the prevalence of sub-clinical infection (55.7% (95%CI, 44.9% to 65.8%)) and identified risk factors for infection. The study found risk of infection was highest in the Grasslands ecoregions compared to the Boreal Transition ecoregion. A case control study looked at risk factors for development of clinical disease. The study followed 23 case farms and control farms with a total of 300 horses sampled. This was the first field study to show that vaccination was efficacious in preventing the development of clinical signs. <p>The inclusion of horse surveillance data in the Saskatchewan Health WNV Integrated Surveillance Initiative was useful; however, it was discontinued due to time constraints, logistics, and declining monetary resources. <p>Since West Nile Virus is a mosquito-borne disease it is highly influenced by environmental changes, spatially and temporally. Discriminant analyses were used to partition Saskatchewan rural municipalities (RM) into categories of risk of infection with WNV based on acquired horse data and different environmental and meteorological data derived from both satellites or climate stations. The result was the creation of yearly predictive risk maps defining low to high risk of infection with WNV for each RM. <p>The 2003 epidemic provided a novel opportunity to study an important zoonotic disease emerging in a new environment. The information gathered will further the knowledge base upon which decisions for prevention of infection and clinical disease are made.

Although avian influenza virus (AIV) infections in domestic poultry are uncommon, transmission of avian influenza from wild waterfowl reservoirs does occur. Depopulation of the infected flock is the typical response to AIV outbreaks in domestic chicken production, causing a loss in profits and accumulation of unexpected expenses. Because it is impossible to know which of many virus subtypes will cause an outbreak, it is not feasible for the U.S. to stockpile vaccines against all possible avian influenza threats. Currently, the U.S. does not routinely vaccinate chickens against influenza due to the inability to differentiate infected from vaccinated animals (DIVA), which would place limitations on its trade markets. A Sindbis virus vector expressing the PR8 influenza strain's M2e peptide was developed as a potential universal DIVA vaccine. M2e is a conserved peptide amongst influenza A viruses; M2e-specific antibodies induce antibody-dependent cytotoxicity or phagocytosis of infected cells, reducing production and shedding of AIV during infection. In this study, chickens were vaccinated at one-month-of-age with parental (E2S1) or recombinant Sindbis viruses expressing the PR8 M2e peptide (E2S1-M2e) by subcutaneous or intranasal routes at high (106 pfu) or low (103 pfu) dosages. Chickens were boosted at 2-weeks post-initial vaccination using the same virus, route, and dosage, then challenged with low pathogenic H5N3 AIV at 0.2 mL of 106/mL EID50 2-weeks post-boost. Serum samples were collected at 1-week and 2-weeks post-vaccination, 2-weeks post-boost, and 2-weeks post-challenge and screened for PR8 M2e-specific IgY antibody production by ELISA. Both high and low dose subcutaneously, as well as high dose intranasally vaccinated E2S1-M2e groups produced significantly higher levels of PR8 M2e-specific IgY antibodies as early as 1-week post-vaccination, while the uninoculated control and E2S1 groups remained negative for all pre-challenge time points. M2e-specific IgY antibodies capable of binding the challenge H5N3 M2e peptide were detected in groups with existing vaccine-induced M2e-specific antibodies pre-challenge, suggesting antibody M2e cross-reactivity. After challenge, all groups developed M2e-specific IgY antibodies and high HI titers, verifying successful AIV infection during challenge and production of hemagglutinin-specific antibodies. Viral shedding titers 4-days post-challenge were used to measure vaccine efficacy and were similar amongst all groups. Microneutralization assay results confirmed that post-boost serum samples, containing only M2e-specific antibodies, were unable to neutralize AIV in vitro. Although the E2S1-M2e vaccine was capable of producing high levels of M2e-specific IgY antibodies when inoculated subcutaneously, these antibodies were not able to reduce viral shedding and therefore did not protect chickens from AIV.

This thesis describes the West Nile virus (WNV) epidemic in horses by exploring all aspects: sub-clinical infection, development of clinical disease and case fatality. All of the collected data were then compiled to create predictive risk maps of WNV infection for the province of Saskatchewan. During the 2003 season, 133 clinical cases were documented with laboratory testing. Week of onset of clinical signs, gender, and coat color were significant predictors of whether the horse died or was euthanized due to severity of clinical signs. Studies of the serological response to vaccination and natural infection were examined to interpret the lab results from over 1100 samples taken from approximately 875 horses in 2003. A serologic study involving 212 horses on 20 farms determined the prevalence of sub-clinical infection (55.7% (95%CI, 44.9% to 65.8%)) and identifed risk factors for infection. The study found risk of infection was highest in the Grasslands ecoregions compared to the Boreal Transition ecoregion. A case control study looked at risk factors for development of clinical disease. The study followed 23 case farms and control farms with a total of 300 horses sampled. This was the first field study to show that vaccination was efficacious in preventing the development of clinical signs. The inclusion of horse surveillance data in the Saskatchewan Health WNV Integrated Surveillance Initiative was useful; however, it was discontinued due to time constraints, logistics, and declining monetary resources. Since West Nile Virus is a mosquito-borne disease it is highly influenced by environmental changes, spatially and temporally. Discriminant analyses were used to partition Saskatchewan rural municipalities (RM) into categories of risk of infection with WNV based on acquired horse data and different environmental and meteorological data derived from both satellites or climate stations. The result was the creation of yearly predictive risk maps defining low to high risk of infection with WNV for each RM. The 2003 epidemic provided a novel opportunity to study an important zoonotic disease emerging in a new environment. The information gathered will further the knowledge base upon which decisions for prevention of infection and clinical disease are made.