Treponema pallidum ssp. pallidum is the causative agent of syphilis, a sexually transmitted infection characterized by multi-stage disease and diverse clinical manifestations. Treponema pallidum undergoes rapid vascular dissemination to penetrate tissue, placental, and blood-brain barriers and gain access to distant tissue and organ sites. The rapidity and extent of T. pallidum dissemination is well documented, but the molecular mechanisms that underlie this process have yet to be fully elucidated. Tp0751 is a T. pallidum adhesin that interacts with vascular factors and mediates adherence to endothelial cells under shear flow. This dissertation explores the molecular interactions and functional outcomes of Tp0751-mediated vascular endothelium adhesion. The findings presented herein demonstrate that recombinant Tp0751 adheres to human macrovascular and microvascular endothelial cells, including cerebral brain endothelial cells. This interaction is confirmed using live T. pallidum, where spirochete- endothelial cells interactions are disrupted with Tp0751-specific antiserum. Further, the 67 kDa laminin receptor (LamR) is identified as an endothelial receptor using affinity chromatography coupled with mass spectrometry to isolate and identify Tp0751-interacting proteins from endothelial cells membrane extracts. Notably, LamR is a brain endothelial cell receptor for other neurotropic invasive pathogens. Evaluation of endothelial intercellular junctions reveals that recombinant Tp0751 and live T. pallidum disrupt junctional architecture. However, transwell solute flux assays reveal that Tp0751 and T. pallidum do not alter endothelial barrier integrity. The transendothelial migration of T. pallidum can be partially abrogated with an endocytosis inhibitor, implying a transcellular route for barrier traversal. However, a subpopulation of T. pallidum localizes to intercellular junctions, indicating paracellular traversal may also be employed. These findings enhance our understanding of the mechanics of T. pallidum attachment to endothelial cells and suggest that T. pallidum may use both paracellular and transcellular mechanisms to traverse the vascular endothelium without altering barrier permeability. A more complete understanding of this process will facilitate vaccine development for syphilis. / Graduate / 2020-06-18

Introduction: Mucosal human papillomavirus (HPV) infection is the most common sexually transmitted infection (STI) and is associated with genitals warts, anogenital cancers, and oropharyngeal cancers. Most sexually active persons will become infected with HPV at some point in their lives, however few will develop HPV-related diseases such as warts, lesions, or cancer as a result of the infection. It is unclear why a minority of individuals fail to clear HPV infection and develop clinical disease. Due to initial associations with cervical lesions, much research has focused on women. Th1 type immune responses have been associated with successful response to HPV infection. Factors such as psychological stress and sleep have been associated with immune function. Stress has been associated with cervical lesions, however no study has evaluated effects of stress or sleep on HPV infection. This research sought to examine the associations between perceived stress and sleep problems with HPV prevalence, incidence, and clearance among men. Methods: Men were tested for 37 individual HPV genotypes every 6 months as part of a large natural history study. A total of 426 men were followed over 1 to 4 visits. Perceived stress was measured with a modified 4-item Perceived Stress Scale (PSS-4) assessing stress in the past six months and was dichotomized into high (scores in the 4th quartile) and low perceived stress. Self-reported sleep problems were measured by seven likert-scale items and categorized as high (4th quartile of sleep problems scores), moderate (second and third quartiles; reference group), and low (first quartile). Three HPV classifications were examined; men were categorized as positive for 'Any HPV' if they tested positive for any of the 37 HPV genotypes in the study protocol, men were categorized as positive for 'Oncogenic HPV' if they tested positive for any oncogenic HPV type, and men were categorized as positive for 'Non-oncogenic HPV' if they tested positive for any non-oncogenic HPV genotype. In the prevalence analysis, men who had no detectable HPV infection with any of the 37 types were the reference group in all analyses. Prevalence ratios and 95% confidence intervals (95% CI) were calculated using Poisson regression with robust variance. For HPV clearance and incidence, Cox regression with the robust sandwich estimator was used to calculated hazard ratios and 95% confidence intervals. Results: A total of 424 men had genotyping results available for the prevalence analysis. High perceived stress was significantly associated with higher prevalence of any HPV infection [PR =1.33 (95% CI: 1.06-1.68)] and oncogenic HPV infection [PR=1.53 (95% CI: 1.06-2.20)], adjusting for demographics, sexual behavior, and sleep problems. High self-reported sleep problems was significantly associated with higher prevalence of oncogenic HPV infection [PR=1.50 (95% CI:1.01-2.13)], adjusting for demographics, sexual behavior, and perceived stress. Perceived stress and self-reported sleep problems were not associated with incidence of HPV infection. Perceived stress was not significantly associated with clearance of HPV infection overall. Among men 50 and older however, men with high stress were significantly less likely to clear any HPV infection than those with low stress adjusting for demographics, HR=0.09 (95% CI: 0.02-0.49). Compared to men with moderate sleep problems, those with high sleep problems were significantly less likely to clear an infection with any HPV type, HR=0.68 (95% CI: 0.49-0.94), or an oncogenic HPV type, HR=0.51 (95% CI: 0.28-0.94), after adjustment for demographics and perceived stress. Discussion: This is the first study to examine associations between HPV infection with perceived stress and self-reported sleep problems. It is also the largest study to examine associations between these exposures and an infection outcome. Results suggest that perceived stress and self-reported sleep problems have independent effects on HPV. Evaluation of perceived stress, biological indicators of stress, objective measures of sleep, and measurement of immune parameters may aid in further elucidating how stress and sleep disturbance are related to HPV infection. Determination of modifiable factors that can influence HPV infection may aid in the prevention of adverse disease outcomes related to infection with this virus. Examining the impact of factors such as perceived stress and sleep problems on HPV infection may aid in risk stratification of patients and allow more targeted interventions among those most at risk for developing disease.

India houses the world’s third largest population of people living with Human Immunodeficiency Virus (HIV) who constitute about 6% of the global HIV burden. In about 2008-9, an estimated 1.9 million [95%CI: 1.5 to 2.5] adults were living with HIV in India. The four southern Indian states of Andhra Pradesh, Karnataka, Maharashtra and Tamil Nadu account for about 60% of estimated HIV infections, although they house only 30% of the adult population. I report that most HIV infections in infected couples in the general population of India (85.4% (95%CI: 80.0, 90.7)) were introduced by the male partner. The per-partnership transmission probability of HIV in the general population was low 29.1% (95%CI: 22.5, 35.7) compared to what has been reported for other STIs. Important theoretical facilitating factors for HIV transmission were associated with HIV infection with nearly equal effect sizes in both genders and across HIV–risk settings (multiple partnerships (OR: 2.46 (95%CI: 1.98, 3.06) and STIs (ORHSV-2: 5.60 (95%CI: 3.37, 9.33); ORSyphilis: 4.12 (95%CI: 2.35, 7.25)). The strength of association of STIs with HIV was consistent. Intervention spending on, or coverage of, STI treatment-focused sex work interventions (per 1000 total district population) was associated with a reduced annual risk of either HIV (- 1.7%, 95%CI: -3.3, -0.10) or syphilis (-10.9%, 95%CI: -15.9, -5.8) infection in young pregnant women in the high-burden southern states. A decreased annual risk of syphilis iii among young pregnant women attending public prenatal clinics in the high-burden southern states was associated with a unit increase (per 1000 total district population) of intervention spending (-0.009%, 95%CI: -0.014, -0.004), number of STIs treated (-10.9%, 95%CI: -15.9, -5.8), FSWs reached (-3.0%, 95%CI: -5.2, -0.7) and condoms distributed (-0.034%, 95%CI: - 0.053, -0.015). Male sexual behaviour (non-regular partnerships and use of female sex work) is the dominant driver of HIV transmission in the general population of south India. Ulcerative STIs were strongly associated with HIV infection in south India and interventions aimed at treating STIs and promoting safer sex practices for FSWs and their clients have resulted in reductions in HIV and syphilis incidence and prevalence in the general population of south India.

India houses the world’s third largest population of people living with Human Immunodeficiency Virus (HIV) who constitute about 6% of the global HIV burden. In about 2008-9, an estimated 1.9 million [95%CI: 1.5 to 2.5] adults were living with HIV in India. The four southern Indian states of Andhra Pradesh, Karnataka, Maharashtra and Tamil Nadu account for about 60% of estimated HIV infections, although they house only 30% of the adult population. I report that most HIV infections in infected couples in the general population of India (85.4% (95%CI: 80.0, 90.7)) were introduced by the male partner. The per-partnership transmission probability of HIV in the general population was low 29.1% (95%CI: 22.5, 35.7) compared to what has been reported for other STIs. Important theoretical facilitating factors for HIV transmission were associated with HIV infection with nearly equal effect sizes in both genders and across HIV–risk settings (multiple partnerships (OR: 2.46 (95%CI: 1.98, 3.06) and STIs (ORHSV-2: 5.60 (95%CI: 3.37, 9.33); ORSyphilis: 4.12 (95%CI: 2.35, 7.25)). The strength of association of STIs with HIV was consistent. Intervention spending on, or coverage of, STI treatment-focused sex work interventions (per 1000 total district population) was associated with a reduced annual risk of either HIV (- 1.7%, 95%CI: -3.3, -0.10) or syphilis (-10.9%, 95%CI: -15.9, -5.8) infection in young pregnant women in the high-burden southern states. A decreased annual risk of syphilis iii among young pregnant women attending public prenatal clinics in the high-burden southern states was associated with a unit increase (per 1000 total district population) of intervention spending (-0.009%, 95%CI: -0.014, -0.004), number of STIs treated (-10.9%, 95%CI: -15.9, -5.8), FSWs reached (-3.0%, 95%CI: -5.2, -0.7) and condoms distributed (-0.034%, 95%CI: - 0.053, -0.015). Male sexual behaviour (non-regular partnerships and use of female sex work) is the dominant driver of HIV transmission in the general population of south India. Ulcerative STIs were strongly associated with HIV infection in south India and interventions aimed at treating STIs and promoting safer sex practices for FSWs and their clients have resulted in reductions in HIV and syphilis incidence and prevalence in the general population of south India.

Introduction: Oil/gas communities across Northeastern British Columbia are experiencing rapid in-migration of young, primarily male workers in response to an economic ‘boom’ in the oil/gas sectors. Accompanying the ‘boom’ has been a rise in rates of sexually transmitted infections (STIs) among young people, with Chlamydia rates among youth in the Northeast exceeding the provincial average by 22%. Previous research indicates that socio-cultural and structural determinants of youth sexual behaviour and access to STI testing are important for understanding youth sexual health disparities – and represent key targets for STI prevention efforts. No other research has explored STIs in this rapidly developing, under-resourced context. Therefore, objectives of this thesis were to: (1) Examine how socio-cultural and structural features related to the oil/gas ‘boom’ affect the sexual behaviour of young people in Fort St. John (FSJ), BC; (2) Gather the perspectives of youth and their service providers on the socio-cultural and structural barriers to STI testing in FSJ; (3) Develop recommendations to improve the accessibility of STI testing. Results: Participants identified 4 main ways in which the socio-cultural and structural conditions created by the ‘boom’ affect sexual behaviours, fuelling the spread of STIs in FSJ: mobility of oil/gas workers; binge partying; high levels of disposable income; and gendered power dynamics. As well, 5 key barriers to STI testing among youth were identified: limited opportunities for access; geographic inaccessibility; local social norms; limited information; and negative interactions with providers. Discussion: These data indicate that the conditions fostered by the ‘boom’ in FSJ exacerbate sexual health inequalities among young people. They can be more widely contextualized as an example of the unintended – but not unexpected – health and social implications of a resource-extraction ‘boom’, illustrating the fallacy of ‘development’ as representing uniformly positive ‘progress’. Recommended actions include STI prevention and testing service delivery models that incorporate a locally tailored public awareness campaign, outreach to oil/gas workers, condom distribution, expanded clinic hours and drop-in appointments, specialized training for health care providers, and intersectoral partnerships between public health, non-profit organizations, and industry. An ongoing knowledge translation internship has been undertaken to implement some of these recommendations.

Persistent infection with certain subtypes of Human papillomavirus (HPV) is a necessary cause of cervical cancer, the second most common cancer among women worldwide. Uptake of HPV vaccines in the targeted Canadian female population has been lower than anticipated. This study’s primary objective was to determine undergraduate women’s perceptions about HPV vaccination. A total of 401 female University of Ottawa undergraduate students completed a newly developed cross-sectional web survey. The prevalence of HPV vaccination was 49%. While the overall attitude towards receiving the vaccine was positive, vaccinated respondents had more favorable attitudes toward the vaccine. Lack of vaccine knowledge and cost were the primary barriers that have prevented HPV vaccination among non-vaccinated respondents. Offering HPV vaccination for women aged 18 to 25 presents a strategy for addressing suboptimal vaccination coverage in the targeted female population and may reduce health inequities demonstrated by variations in cervical cancer incidence within jurisdictions.

Introduction: Oil/gas communities across Northeastern British Columbia are experiencing rapid in-migration of young, primarily male workers in response to an economic ‘boom’ in the oil/gas sectors. Accompanying the ‘boom’ has been a rise in rates of sexually transmitted infections (STIs) among young people, with Chlamydia rates among youth in the Northeast exceeding the provincial average by 22%. Previous research indicates that socio-cultural and structural determinants of youth sexual behaviour and access to STI testing are important for understanding youth sexual health disparities – and represent key targets for STI prevention efforts. No other research has explored STIs in this rapidly developing, under-resourced context. Therefore, objectives of this thesis were to: (1) Examine how socio-cultural and structural features related to the oil/gas ‘boom’ affect the sexual behaviour of young people in Fort St. John (FSJ), BC; (2) Gather the perspectives of youth and their service providers on the socio-cultural and structural barriers to STI testing in FSJ; (3) Develop recommendations to improve the accessibility of STI testing. Results: Participants identified 4 main ways in which the socio-cultural and structural conditions created by the ‘boom’ affect sexual behaviours, fuelling the spread of STIs in FSJ: mobility of oil/gas workers; binge partying; high levels of disposable income; and gendered power dynamics. As well, 5 key barriers to STI testing among youth were identified: limited opportunities for access; geographic inaccessibility; local social norms; limited information; and negative interactions with providers. Discussion: These data indicate that the conditions fostered by the ‘boom’ in FSJ exacerbate sexual health inequalities among young people. They can be more widely contextualized as an example of the unintended – but not unexpected – health and social implications of a resource-extraction ‘boom’, illustrating the fallacy of ‘development’ as representing uniformly positive ‘progress’. Recommended actions include STI prevention and testing service delivery models that incorporate a locally tailored public awareness campaign, outreach to oil/gas workers, condom distribution, expanded clinic hours and drop-in appointments, specialized training for health care providers, and intersectoral partnerships between public health, non-profit organizations, and industry. An ongoing knowledge translation internship has been undertaken to implement some of these recommendations.

Chlamydia trachomatis infections are among the most frequently reported causes of human sexually transmitted infection. In Australia, the reported rate of infection in 2004 reached 175 per 100,000 population, the highest rate since surveillance of the condition began in 1991. Severe adverse sequelae that commonly occur following progression of the infection from the lower to the upper genital tract include pelvic inflammatory disease, infertility and ectopic pregnancy. However the frequent prevalance of asymptomatic infection makes diagnosis and treatment often late and therefore ineffective against upper genital tract complications. Hence there is a great need to develop a vaccine to protect against the sexual transmission of C.trachomatis. Despite many years of research investigating potential vaccine strategies to prevent sexually transmitted C.trachomatis infections, there remains no commercially available C.trachomatis vaccine. Early research showed that the use of live, attenuated or inactivated whole Chlamydia as a vaccine was not a viable option due to adverse effects caused by immunopathogenic cellular components. The early human vaccine trials that utilized whole chlamydial cells and resulted in exacerbated disease when immunized individuals were re-exposed to Chlamydia have led to the investigation of chlamydial subunit components as potential vaccine antigens. The most widely investigated vaccine candidate antigen is the major outer membrane protein (MOMP) as it is known to be immunogenic and surface exposed. Much research using this antigen has been undertaken with the antigen being delivered as a protein, peptide or DNA, via many mucosal and systemic routes of immunization, and in combination with various vaccine adjuvants. However, at best only partial protection against a chlamydial genital tract infection has been achieved. Only a few alternative candidate antigens have been investigated as potential vaccine targets to protect against chlamydial infections. These include the outer membrane porin PorB, the large cysteine rich outer membrane protein Omp2 and the heat shock proteins DnaK and GroEL. Although other candidate antigens have been predicted in various models of chlamydial infection (Finco et al., 2005; Stemke-Hale et al., 2005; Li et al., 2006), few have been tested for their protective efficacy. The aim of this study was to use expression library immunization to screen the whole C.muridarum genome for novel vaccine candidates capable of protecting against a chlamydial genital tract infection. C.muridarum was selected as the disease model for chlamydial genital tract infection as it has similarities to C.trachomatis in pathogenesis, immune response to infection and gene content and order. Once protective antigens had been isolated from an expression library, these were screened individually for immunogenicity and protective efficacy in the C.muridarum model of infection. An expression library containing over 21,000 recombinant C.muridarum clones was constructed and divided into pools of clones. DNA was extracted from these pools and used to immunize mice through gene gun technology, delivering 1μg of DNA to the abdomen of mice. Following the immunization regime, mice were challenged intra-vaginally with live C.muridarum as this route of infection best resembles the natural route of infection that is responsible for the sexual transmission of C.trachomatis in humans. Four in vivo screens of the C.muridarum expression library, each time using reduced numbers of clones, resulted in the identification of seven novel vaccine antigens that conferred protection against a genital tract challenge infection in mice. These warrant further investigation as vaccine antigens in the development of a vaccine against C.trachomatis infection. The identified antigens include antigens not conventionally believed to be potential vaccine candidates such as hypothetical proteins and housekeeping genes, including a DNA gyrase subunit, TC0462, and the ATP-dependent Clp protease, ATP-binding subunit ClpC, TC0559. Other antigens identified were more traditional, surface exposed vaccine targets that have not been previously investigated as vaccine targets, including a novel outer membrane protein, TC0512, a polymorphic membrane protein, TC0693, and TC0850, a protein of the type three secretion system, a family of proteins that allow gram-negative bacteria to inject virulence related proteins into the cytoplasm of a host cell. All antigens were shown to be partially protective with the putative outer membrane protein TC0512 showing an overall reduction in chlamydial burden of 55% and other antigens showing overall reductions in chlamydial burden of 26 - 44%. These antigens were also either capable of stimulating an immune response, or predicted to contain epitopes that may stimulate strong immune responses and so warrant further investigation as vaccine antigens to protect against chlamydial genital tract infections. The results of this research demonstrate that it is possible to identify novel vaccine targets through screening an expression library in a disease model. This study has identified several novel vaccine targets that are partially-protective against a C.muridarum infection and that are thought to be capable of stimulating strong immune responses. These antigens have high homology with C.trachomatis sequences, indicating that they have potential as vaccine candidates capable of protecting against the serovars of C.trachomatis that cause sexually transmitted infections in humans. Although the protection observed in this study was only partial, the immunization strategy utilised only fragments of the genes, an immunization mechanism known to elicit Th2 type immune responses, and no adjuvant to enhance the immunogenicity of the antigens. Through different immunization routes and in conjunction with adjuvants that stimulate Th1 type immune responses, complete protection against chlamydial genital tract infections may be achieved.

Introduction: Oil/gas communities across Northeastern British Columbia are experiencing rapid in-migration of young, primarily male workers in response to an economic ‘boom’ in the oil/gas sectors. Accompanying the ‘boom’ has been a rise in rates of sexually transmitted infections (STIs) among young people, with Chlamydia rates among youth in the Northeast exceeding the provincial average by 22%. Previous research indicates that socio-cultural and structural determinants of youth sexual behaviour and access to STI testing are important for understanding youth sexual health disparities – and represent key targets for STI prevention efforts. No other research has explored STIs in this rapidly developing, under-resourced context. Therefore, objectives of this thesis were to: (1) Examine how socio-cultural and structural features related to the oil/gas ‘boom’ affect the sexual behaviour of young people in Fort St. John (FSJ), BC; (2) Gather the perspectives of youth and their service providers on the socio-cultural and structural barriers to STI testing in FSJ; (3) Develop recommendations to improve the accessibility of STI testing. Results: Participants identified 4 main ways in which the socio-cultural and structural conditions created by the ‘boom’ affect sexual behaviours, fuelling the spread of STIs in FSJ: mobility of oil/gas workers; binge partying; high levels of disposable income; and gendered power dynamics. As well, 5 key barriers to STI testing among youth were identified: limited opportunities for access; geographic inaccessibility; local social norms; limited information; and negative interactions with providers. Discussion: These data indicate that the conditions fostered by the ‘boom’ in FSJ exacerbate sexual health inequalities among young people. They can be more widely contextualized as an example of the unintended – but not unexpected – health and social implications of a resource-extraction ‘boom’, illustrating the fallacy of ‘development’ as representing uniformly positive ‘progress’. Recommended actions include STI prevention and testing service delivery models that incorporate a locally tailored public awareness campaign, outreach to oil/gas workers, condom distribution, expanded clinic hours and drop-in appointments, specialized training for health care providers, and intersectoral partnerships between public health, non-profit organizations, and industry. An ongoing knowledge translation internship has been undertaken to implement some of these recommendations. / Medicine, Faculty of / Population and Public Health (SPPH), School of / Graduate

Persistent infection with certain subtypes of Human papillomavirus (HPV) is a necessary cause of cervical cancer, the second most common cancer among women worldwide. Uptake of HPV vaccines in the targeted Canadian female population has been lower than anticipated. This study’s primary objective was to determine undergraduate women’s perceptions about HPV vaccination. A total of 401 female University of Ottawa undergraduate students completed a newly developed cross-sectional web survey. The prevalence of HPV vaccination was 49%. While the overall attitude towards receiving the vaccine was positive, vaccinated respondents had more favorable attitudes toward the vaccine. Lack of vaccine knowledge and cost were the primary barriers that have prevented HPV vaccination among non-vaccinated respondents. Offering HPV vaccination for women aged 18 to 25 presents a strategy for addressing suboptimal vaccination coverage in the targeted female population and may reduce health inequities demonstrated by variations in cervical cancer incidence within jurisdictions.