Tuberculosis, caused by Mycobacterium tuberculosis, is one of the most prevalent infectious diseases inflicting humankind. The World Health Organization estimates that one third of the world's population, approximately 2.2 billion people, is infected with TB with a mortality of 1.7 million people annually. Currently, the WHO estimates that each year more than 9 million people develop TB. Bacille Calmette-Guérin (BCG), an attenuated strain of M. bovis, is the only licensed TB vaccine in the world. Clinical studies have shown childhood vaccination with BCG to be protective against disseminating and meningeal forms of TB. However, the efficacy of BCG against pulmonary TB in adults has been variable and inconsistent (0-80%). The objective of this study is to develop and test the efficacy of the B. abortus vaccine strain RB51 as a platform for expression of M. tuberculosis antigens (Ag85B, ESAT6 and Rv2660c) and induction of a protective immune response against M. tuberculosis and B. abortus challenge in mice. Here we report the construction of two recombinant strains of B. abortus vaccine strain RB51 capable of expressing mycobacterial antigens Ag85B, ESAT6 and Rv2660c. Our studies show that expression of mycobacterial antigens in strain RB51 lead to induction of antigen-specific immune responses characterized by secretion of IgG2a antibodies as well as of IFN- and TNF-α. Mice immunized with a combination of two strains of RB51 in equal numbers, one carrying Rv2660c-ESAT6 and another carrying Ag85B, led to a 0.90 log reduction in CFU burden with significance nearly reaching borderline (p = 0.052). However, when mice were primed with the same strains of RB51 and boosted with proteins Ag85B and ESAT6, a significant level of protection (1 log reduction) compared to the PBS vaccinated group was achieved. The protection levels conferred by this vaccination strategy was similar to that conferred by BCG vaccine. In conclusion, we have shown that recombinant RB51 strains expressing mycobacterial protective antigens result in stimulation of antigen specific immune response without altering the vaccine efficacy in protecting against the more virulent strain of B. abortus 2308. These recombinant vaccines could potentially be used to protect against M. tuberculosis infection. / Ph. D.

Contagious bovine pleuropneumonia (CBPP) is a bovine bacterial disease of major economic importance in sub-Saharan Africa. Vaccination has been recommended to control the disease in endemic areas such as the Maasai ecosystems of Kenya and Tanzania; however, the currently used live attenuated vaccine has been reported to have poor vaccine safety and efficacy. To compare standard (current) and an improved (buffered) version of the live CBPP-vaccine, several epidemiological studies were carried out in Maasai cattle in Kenya between 2006 and 2008. Specifically, the aims were to estimate CBPP seroprevalence at herd and animal level; to identify risk factors for seroprevalence at both levels; to investigate the spatial distribution of seroprevalence; to compare post vaccination adverse events in cattle vaccinated with a standard and a buffered vaccine, and finally to compare efficacy of the two vaccines to induce seroconversion and to prevent development of clinical signs suggestive of CBPP. A cross-sectional study was carried out in 6872 cattle in 175 randomly selected herds from Loita and Mara divisions. A competitive ELISA revealed that 85% of the herds in the area had at least one seropositive animal and that seropositive herds were harbouring 11% seropositive cattle. A complement fixation test revealed that 46% of the herds had at least one seropositive animal and that seropositive herds were harbouring 4% seropositive cattle. A multivariable logistic regression analysis of the seroprevalence indicated that previous vaccination against CBPP, a history of CBPP outbreaks in the herd, animal age and the location of the herd in the division of Mara were positively correlated to seroprevalence. To investigate the observed difference in herd seroprevalence between the two divisions further, a spatial analysis was conducted. A SatScan test revealed clusters in Mara in areas identified by veterinary personnel as CBPP ‘hot spots’. A logistic regression using spatial information identified that location in the midland agro-ecological zone or close to a river and vaccination were positively associated with seroprevalence. To compare safety and efficacy of a standard and a buffered vaccine, two cohorts of approximately 40,000 cattle were used. The study showed that within 100 days post vaccination, 6.2 cattle per 1000 vaccinates developed adverse events, 4.1 of which were specifically attributable to vaccination and ranging from swelling of the tail to the tail sloughing off. This study revealed a slightly higher incidence of adverse events in cattle vaccinated with the buffered vaccine compared to the standard vaccine. A comparison of the efficacy of the two vaccines revealed that cattle vaccinated with the buffered vaccine had higher odds of seroconversion and lower odds of developing symptoms of CBPP, three and twelve months post vaccination respectively. The epidemiological studies conducted clearly show wide spread seroprevalence in the Maasai cattle. Given the (spatial) heterogeneity observed, control measures should probably be targeted in areas of increased risk (clusters). However, positive association of vaccination and seropositivity call for better diagnostics tests that can differentiate vaccinated from infected animals. Vaccination with buffered vaccine resulted in increased seroconversion, decreased clinical signs indicative of CBPP post vaccination and low seroprevalence post ‘outbreak’. Nevertheless, the increase in adverse events related to the buffered vaccine calls for further research into safer CBPP vaccines.

Thesis (DR. P.H.)--University OF MICHIGAN.

Salmonella infections remain one of the most common food borne diseases worldwide. Gastroenteritis, which can be caused by many non-typhoidal Salmonella (NTS) serovars, is relatively common in North America. One of the main risk factors of NTS gastroenteritis is travel to endemic areas in the developing world. The current treatment of NTS infections with antibiotics is reserved for severe cases. A growing concern with antibiotic use is that clinical isolates are becoming drug resistant. Although most NTS infections are self-limiting in nature, the burden on the body and recovery can take several months. Thus, it is vital to prevent NTS infections rather than solely rely on treatment. We have previously discovered two novel surface associated polysaccharides in Salmonella: O-Antigen capsule and X-factor. Not only O-Antigen Capsule is considered a common surface antigen, but its’ genes were found to be expressed during in vivo infections in mice. Such an antigen would be a suitable candidate in developing a vaccine against Salmonella induced gastroenteritis. The goal of this research was to evaluate the use of O-Antigen capsule to develop a traveler’s vaccine for NTS associated gastroenteritis. Results and Conclusions: We have developed a purification protocol and purified the capsule and X-factor from Salmonella Typhimurium, Enteritidis, and Heidelberg. Lipopolysaccharide (LPS) was co-isolated with O-Antigen capsule, but removed using Triton extraction. Salmonella LPS is strain-specific and an adaptive immune response against LPS will not provide cross-protection. We generated specific immune sera in rabbits to recognize O-Antigen capsule and X-factor produced by Salmonella Typhimurium and Enteritidis. We used a mouse model to determine the immunization dose of O-Antigen capsule and showed that conjugation is necessary to enhance the immune response in mice. To boost capsule production, we analyzed PyihUTSRQPO activity using a luciferase-based reporter system. Deletion of a putative transcriptional repressor (YihW) resulted in over 100-fold increase in PyihUTSRQPO confirming YihW as a repressor. We have also looked at the effect of growth media, temperature, and sugar precursors on PyihUTSRQPO activity, and were able to show that PyihUTSRQPO has highest activity in Tryptone broth at 30oC in the absence of any additional sugars.

The quadrivalent (q-) human papillomavirus (HPV) vaccine is praised for its near perfect efficacy of 98% in the per-protocol population and minimal safety concerns. Adherence to the dosing schedule of 0, 2 and 6 months outside clinical trials has not yet been described. Furthermore, clinical trials were underpowered to detect rare, but serious, adverse events including convulsions, seizures and epilepsy in young girls targeted by American and Canadian national advisory committees. This retrospective cohort study followed Grade 8 girls eligible for Ontario’s HPV immunization program during the 2007/08 to 2010/11 campaign years. Using Ontario’s immunization and health databases, baseline characteristics, qHPV vaccination, dates of qHPV vaccination and diagnoses of serious neurological events were identified for each cohort member. The proportions of girls who initiated and completed the qHPV vaccine program were determined. Adherence to the recommended dosing intervals and for ‘time-to-series completion’ was calculated as the proportion of eligible girls whose number of days between doses complied with the recommended dosing interval. A self-matched, case only approach was used to estimate the age-adjusted rate ratio (RR) of neurological events in the 0-30 day period following qHPV vaccination. The primary study endpoint was a composite of the first occurrence of a convulsion, seizure or epilepsy. Secondarily, an epileptic seizure only endpoint was assessed, as were the influence of a number of predisposing risk factors. An overall uptake of 50.24% was observed, of which, 87.02% received at least three doses. Adherence to the recommended dosing interval was most difficult in scheduling of the second dose (70.80%). There was no increased risk observed for the primary endpoint in the 0-30 days following qHPV vaccination (RR 1.01, 95% CI 0.92-1.10). However, this association was modified in girls with predisposing risk factors for epilepsy. There was an increased risk observed for the epileptic seizure only endpoint (RR 1.64, 95% CI 1.28-2.10). In Ontario, the overall uptake of the qHPV vaccine is low. Once initiated, series completion is high, with the majority receiving the vaccine in a timely manner. A risk for epileptic seizures following vaccination may be limited to girls with predisposing risk factors. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2012-09-28 17:56:59.608

Background: The qHPV vaccine has the potential to significantly reduce the burden of HPV-related diseases, including cervical cancer. However, a recent systematic review of clinical trials has suggested that the risk of bronchospasm may be increased by this vaccine, and a large observational study has reported an increased risk of anaphylaxis. Objectives: To determine whether qHPV vaccination increases the risk of incident asthma, asthma exacerbation, and anaphylaxis. Methods: A population-based retrospective cohort of grade 8 girls eligible for Ontario’s HPV immunization program between 2007 and 2011 was identified using the province’s administrative health and immunization databases. Cohort members were followed from September 1st of their grade 8 year until their date of death or end of study (March 31st, 2012). The self-controlled case series method, a self-matched, case-based analysis was used to assess the effect of qHPV vaccination on the risk of SRREs, and rate ratios (RRs) and 95% confidence intervals for each outcome was estimated using conditional Poisson regression. Results: The cohort consisted of 125,575 girls with a mean age of 13.2 years, 57.7% of whom received at least one dose of the qHPV vaccine. During an average of 2.5 years of follow-up, 1473 cases of incident asthma, 901 of asthma exacerbation and 38 of anaphylaxis were identified. HPV vaccination was not associated with an increased risk of incident asthma or asthma exacerbation (RRadj 0.76, 95% CI 0.37-1.54 and RRadj 0.74, 95% CI 0.27-2.00, respectively), and these associations were unchanged by the presence of risk factors and time since vaccination. There was also no evidence of an increased risk of anaphylaxis following qHPV vaccination as demonstrated by an absence of cases of anaphylaxis occurring on the day of vaccination. Conclusions: This large, population-based study provides strong evidence that the qHPV vaccine does not increase the risk of developing or exacerbating asthma, and additional evidence for the lack of an increased risk of anaphylaxis in the younger populations targeted by HPV immunization programs. These findings add to the growing body of evidence on the safety of the qHPV vaccine. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2014-04-16 19:20:41.019

Thesis (DR. P.H.)--University OF MICHIGAN.

The purpose of these investigations was to isolate and purify the largest of several antigens demonstrable in rabies-infected suckling mouse brains. The biochemical and biophysical properties of the antigen were studied with a view to elucidating its contribution to the intracellular synthesis and the structure of the virus particles. Extracts of normal and infected suckling mouse brains were purified by precipitation at pH 4.5 and freed of the smaller antigens by centrifugation prior to digestion with RNAase, DNAase and trypsin. The large antigen was purified by enzyme treatment, preparative ultracentrifugation, exclusion chroma tography and gradient centrifugation and appeared as rings varying in diameter between 8 and 12 mμ when examined by electron microscopy. Methods for the chemical estimation of pentose, deoxypentose and nitrogen were modified to meet the requirements of this investigation, and these techniques were used to determine the composition of the purified antigen. The antigen is a ribonucleoprotein, and found to be resistant to RNAase, DNAase, trypsin and chymotrypsin. A purified solution of the antigen contained 7.3μg RNA/ml., 11.4μg protein/ml and probably a trace of DNA. The success of this programme has resulted in the accumulation of certain original information which has been used in clari£ying the nature and structure of the largest soluble antigen.

Vaccinations are among the greatest accomplishments of public health. However, many parents are choosing not to vaccinate. The purpose of this study was to explore the association between social media influence and parents' decisions to vaccinate their children. The health belief model indicates that individuals' likelihood of engaging in a health-related behavior is determined by their perceptions of susceptibility, severity, benefits, and barriers. The research questions addressed whether there is an association between parents' perception of their children's disease susceptibility and their decisions about vaccination, and whether there is an association between exposure to messaging from social media and parents' decision to vaccinate. A quantitative, cross-sectional research design was used. The primary dependent variable was vaccination choices, and the primary independent variable was exposure to information about vaccination through social media. Data were gathered through a questionnaire administered to 269 White parents residing in Illinois with their own children between the ages of 0 and 18 years living with them. Binomial logistic regression showed that there was not a statistically significant relationship between parents' perception of disease susceptibility and vaccination choice or between parents' vaccination choice and exposure to online antivaccine advertisements. These study findings help in defining an overall picture of vaccine hesitancy in the United States. By focusing on the predictors of this behavior, it may be possible to implement interventions to combat the antivaccine movement with the goal of increasing vaccine compliance among parents.

Purpose: The purposes of this research are to evaluate the effectiveness of a vaccine education module (VEM) in 1) contributing to new vaccine knowledge of university freshmen; and 2) identifying common vaccine concerns of university freshmen before and after completing the VEM. Methods: A VEM, including information about vaccine-preventable diseases, benefits of vaccines, principles of community or herd immunity, and where to go to get vaccinated, was created for freshman students. Student vaccine concerns were identified using a pretest/posttest quasi-experimental design using an online questionnaire before and after completing the VEM. After the VEM, participants were also asked to identify newly acquired knowledge. Results: Prior to viewing the VEM, the most common participant vaccine theme was the overall decrease of vaccination rates in the general population. After completing the VEM, the most common vaccine concern was the erosion of community immunity. The second most common theme were concerns about vaccine safety. Participants were also concerned about their own vaccination status. When asked what new knowledge they gleaned from the VEM, participants most frequently reported learning information about communicable diseases. Data were collected in the fall of 2019. Conclusions: Following the completion of the VEM, freshman university students reported fewer concerns about vaccine safety and more concerns regarding their current vaccination status. This demonstrates how a VEM contributes to vaccination knowledge and addresses vaccination concerns in university students.