Mosquito-borne diseases account for hundreds of thousands of deaths each year, highlighting the need for successful intervention methods, which can be targeted at either the pathogen, mosquito vector, or human host. This thesis aims to contribute to better intervention methods focused against malaria and dengue by either (i) improving available research tools, (ii) enhancing the understanding of a promising intervention method or (iii) designing new intervention candidates. Firstly, a superior method for studying in vitro malaria infection of the liver is shown, with implications for vaccine and drug interventions. Secondly, the biology of Wolbachia infection in Anopheles gambiae mosquitoes in the context of the target of rapamycin signalling cascade is investigated in an attempt to improve our understanding of its malaria inhibitory phenotype and inability to stably infect An. gambiae mosquitoes. Finally, an algorithm is developed for the design of a hypothesis driven conservation-based vaccine against viral mosquito diseases with a particular focus on dengue.

To investigate how an infectious disease spreads, it is desirable to use the observed surveil­lance data to discover the underlying (often hidden) disease transmission networks. Previous studies have provided methods for inferring information diffusion networks in which each node corresponds to an individual person within the diffusion network. However, in the case of disease transmission, to effectively propose and implement intervention strategies, it is more realistic and reasonable for policy makers to study the diffusion patterns at a metapop­ulation level, that is, to consider disease transmission networks in which nodes represent subpopulations, and links indicate their interrelationships. Such networks can be useful in several ways: (i) to investigate hidden impact factors that in.uence epidemic dynamics, (ii) to reveal possible sources of epidemic outbreaks, and (iii) to practically develop and/or improve strategies for controlling the spread of infectious diseases. Therefore, this thesis addresses the problem of inferring disease transmission networks at a metapopulation level. A network inference method called NetEpi (Network Epidemic) is developed and evaluated using both synthetic and real-world datasets. The experimental results show that NetEpi can recover most of the ground-truth disease transmission networks using only surveillance data.

The purpose of this thesis is to evaluate a vaccination education module and evaluate its effectiveness to improve vaccine beliefs and behaviors among college freshmen. The participants included 177 college freshmen at one Utah university. Participants were eligible for this study if admitted as a new freshman during the 2019-2020 school year. The study was a cross-sectional pre- and post-education evaluation assessing vaccine beliefs and behaviors using a Likert-type scale. After completing the vaccination education module, participants' vaccine beliefs and behavioral intentions improved. Participants reported they were more likely to be up-to-date on personal vaccines and more likely to expect other students to be up-to-date on their vaccinations. Participants were more likely to ask other students to vaccinate and were also more likely to ask their family members to be vaccinated. In conclusion this online vaccination education module effectively improved participants' vaccine beliefs and behavioral intentions.

Thesis (M.Sc.) (Applied Mathematics) --University of Limpopo, 2008. / In this dissertation, two non-linear mathematical models are proposed and analyzed to investigate the spread of infectious diseases in a variable size population through horizontal transmission in the presence of preventive or therapeutic vaccines which are capable of inducing temporary immunity and wane in time. In modeling the transmission dynamics, the population is divided into three subclasses namely; Susceptibles, Infectives and Vaccinated groups. It is assumed that both Vaccinated and Susceptible individuals are recruited into the community and can only become infected via contacts with the infectives group but the rate at which the vaccinated group may contract the diseases is extremely very low depending on the efficacy of the vaccine. All infectives are assumed to move at a constant rate to both Vaccinated and Susceptible groups. These models are analyzed by using the stability theory of differential equations and numerical simulation. The models exhibit two equilibria namely; the disease-free and the endemic equilibria. It is shown that if the vaccination reproduction number R0 < 1, the disease-free equilibrium is always globally asymptotically stable and in such a case the endemic equilibrium does not exist and the disease can be totally eliminated in the community. However, if R0 > 1, a unique endemic equilibrium exists that is locally asymptotically stable and consequently the equilibrium values of infective, vaccinated and susceptible population can be maintained at desired levels. Numerical simulations implemented on MAPLE using both Adomian decomposition technique and Runge-Kutta integration schemes, support our analytical conclusions and illustrate possible behaviour scenarios of the models. / International Pentecostal Holiness Church, Limpopo Provincial Treasury, National Student Financial Aid Scheme and National Research Foundation

Call number: LD2668 .T4 1943 C6 / Master of Science

Hepatitis C Virus currently affects up to 3% of the world’s population. There is no effective vaccine yet available and the natural immune response to infection is largely inefficient. Progress has been made in isolating several broad-acting neutralizing antibodies that target the viral envelope protein E2. However, a dominant element of the epitopes targeted is an overlap with the highly conserved CD81 binding sites. Various E2 constructs were investigated as possible targets to be used in phage display panning of a combinatorial library of the phagemid vector pComb3H. HVR2 deletion showed optimal exposure of the CD81 binding sites and D535A disrupted known CD81 epitopes. A selection technique was designed to improve exposure of conserved sites on an E2 construct target molecule that disrupts CD81 epitopes while remaining conformationally correct. Optimisation of the screening methodology was used to assess the quality of enrichment of the library panning along with more efficient selection of specific clones. The approach adopted in this project isolated Fab clones specifically reactive to the protein target, one of which also showed preferential binding in acidic environments. Taken together, the information gathered on E2 and the implementation of the phage display method described will contribute to more effective ways of isolating novel antibodies.

published_or_final_version / Nursing Studies / Master / Master of Nursing

published_or_final_version / China Development Studies / Master / Master of Arts in China Development Studies

This dissertation examines factors associated with healthcare-associated infections (HAIs) in four acute care hospitals located in New York City. Specifically, this investigation focuses on the role that the physical environment plays with regard to patient-to-patient transmission. The initial analyses describe the scope of the problem by reporting the incidence of HAIs and antimicrobial resistance over a seven-year period in the study institutions. In total, 19,052 HAIs were identified among 761,426 discharges. HAI rates fell over time within all hospitals and for all organisms and infection types included in the study, and the odds of acquiring an HAI decreased significantly over time for all organisms. Resistance levels were stable for Enterococcus spp., Staphylococcus aureus, Acinetobacter baumannii, and Streptococcus pneumoniae. Multidrug resistance increased for Pseudomonas aeruginosa and decreased for Klebsiella pneumoniae, though imipenem resistance among K. pneumoniae climbed sharply in 2011. A systematic literature review is presented to summarize what is known and unknown about how patients’ exposure to infected or colonized concurrent roommates and prior bed occupants affects their risk of developing HAIs. Eighteen articles meeting the inclusion criteria were identified. More than half reported at least one statistically significant positive association between the infection/colonization status of a roommate or previous room occupant and the development of HAIs. Only a single article identified a statistically significant negative association. The remainder found no associations that reached statistical significance, though this may be due to the fact that they were insufficiently powered. The dissertation concludes with a matched case-control study designed to quantify the association between having a prior bed occupant or roommate with a positive blood, respiratory, urine, or wound culture and subsequent infection with the same organism. In a multivariable analysis controlling for patient characteristics and mutually controlling for each exposure, the odds of being exposed to a prior bed occupant with the same organism were 5.83 (95% Confidence Interval [3.62, 9.39]) times greater for cases versus controls and the odds of being exposed to a roommate with the same organism were 4.82 [3.67, 6.34] times greater.

The human non-integrin laminin receptor (LamR) is a multifunctional protein which is localised to a number of sub-cellular locations. LamR is a component of the ribosome and has a number of intracellular functions; it also acts as an extracellular receptor for laminin, growth factors, pathogenic microorganisms, prion proteins, toxins and the anticarcinogen epigallocatechin gallate (ECGC). Although LamR is present in most cellular compartments, its overexpression in many types of cancer cells suggests a vital role for LamR in tumor-cell migration and invasion. There are two isoforms of laminin receptor: the monomeric 37-kDa laminin receptor precursor (37LRP) and the mature 67-kDa laminin receptor (67LR). Although the precise molecular nature of 67LR is unclear, accumulating evidence strongly suggest that 37LRP can undergo homo- and/or hetero-dimerization with Galectin-3 (Gal-3) to form mature 67LR. A recent study demonstrated that both homo- and heterodimer LamR forms are present on the cell surface, where they form distinct populations. Neisseria meningitidis, Streptococcus pneumoniae and Haemophilus influenzae type b (Hib) are major causes of bacterial meningitis. The contribution of LamR in traversal of the blood brain barrier (BBB) by neurotropic viruses is well established and interaction with LamR was recently found to be critical for initiation of bacterial contact with the blood brain barrier (BBB). These bacteria bind LamR via the surface protein adhesins: meningococcal PilQ and PorA; pneumococcal CbpA; and H. influenzae OmpP2. Further investigations showed that the fourth and second extracellular loops of meningococcal PorA and OmpP2 of H. influenzae, respectively, are responsible for LamR binding. The work presented here consists of two complementary projects in which a number of approaches were taken to characterise the ligand-binding domains of LamR. The first project aimed to identify sites on LamR that are critical for binding the ligands of bacterial meningeal pathogens. The second project aimed to identify residues that contribute to the stability of LamR homodimers and the heterodimer with Gal-3. Several mutations were introduced into full-length human LamR, either by deletion mutations within the C-terminal domain (CTD) of LamR using inverse polymerase chain reaction (IPCR), or by single-amino acid substitution in the N-terminal domain (NTD) of LamR using site-directed mutagenesis. Protocols for large-scale expression of full-length and truncated LamR proteins in human cells were developed, as well as non-denaturing purification protocols. We hypothesised that bacteria-binding domains could be located on both the NTD and CTD of LamR. In vivo examination using ELISA assays, in which the interaction of LamR and whole bacteria or purified recombinant PorA or PilQ were tested identified several novel sites on LamR that contributed significantly to binding of the bacterial ligands. These sites include amino acids 206-229 and 263-282, located within the CTD, and Tyrosine 156 in the NTD, each of which contributed to the binding of meningococcal PorA, and more specifically it’s fourth extracellular loop. Furthermore, three sites on LamR comprising amino acids 206-229 and 263-282 within the CTD and Tyrosine 139 in the NTD were shown to contribute to binding pneumococcal CbpA, OmpP2 and Loop two of OmpP2 of H. influenzae. These results indicate that the three neuroinvasive bacteria share the same binding sites on LamR. Bimolecular fluorescence complementation (BifC) coupled with flow cytometry and confocal microscopy revealed the vital contribution of amino acid residues Arginine 155, Tyrosine 156 and Lysine 166 (all within the NTD of LamR) for the homodimerization and heterodimerization of LamR with Gal-3. The dimerization of two meningococcal host receptors, LamR and Gal-3, may help to extend spectrum of their bacterial adhesins, which may act cooperatively or synergistically at different stages of infection. Information about the residues in LamR that contribute to the stabilization of LamR dimers has implications for the role of LamR dimers in the pathogenesis of bacterial meningitis. Identification of bacteria-binding domains on LamR is of particular interest for development of vaccines or therapeutic interventions that provide protection against the three major meningitis-causing bacteria. The aim of the current work was first to localise the domains of LamR responsible for binding with PorA and PilQ of N. meningitidis; CbpA and OmpP2 of S. pneumonia, and OmpP2 of H. influenzae. Also, previous studies have shown conspicuous homodimerisation of 37LRP and heterodimerisation with Gal-3. Our second aim was to identify of amino acid residues involved in 37LRP self-association and heterodimer formation with Gal-3. In current work, several regions of LamR were hypothesised to constitute the binding site for the bacterial ligands; these predictions were based on previous studies on LamR binding domains and the crystal structure of laminin receptor. Also, to investigate both homo and heterodimerisation of LamR, the involvement of several putative amino acid residues within 37LRP in LamR dimerisation was was hypothesised.