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ABSTRACT In terms of prevalence, human suffering and costs dengue infections are the most important arthropod-borne viral disease worldwide. Dengue virus (DENV) is a mosquito-borne flavivirus and the etiological agent of dengue fever and dengue hemorrhagic fever. Thus, development of a safe and efficient vaccine constitutes an urgent necessity. Besides the traditional strategies aim at generating immunization options, the usage of viral vectors to deliver antigenic stimulus in order to elicit protection are particularly attractive for the endeavor of a dengue vaccine. The viral vector (MVvac2) is genetically equivalent to the currently used measles vaccine strain Moraten, which adds practicality to my approach. The goal of the present study was to generate a recombinant measles virus expressing structural antigens from two strains of DENV (DENV2 and DENV4) The recombinant vectors replication profile was comparable to that of the parental strain and expresses either membrane bound or soluble forms of DENV2 and DENV4 E glycoproteins. I discuss future experiments in order to demonstrate its immunogenicity in our measles-susceptible mouse model.
ContributorsAbdelgalel, Rowida (Author) / Reyes del Valle, Jorge (Thesis advisor) / Hogue, Brenda (Committee member) / Frasch, Wayne D (Committee member) / Arizona State University (Publisher)
Created2013
Description
Vaccine opposition is a growing problem in developed countries where dropping vaccination rates threaten general public health by laying the foundation for resurgence and reemergence of previously eradicated infectious diseases. This thesis argues that the current movement is only the most recent incarnation of opposition that has co-evolved with vaccine practices for the duration of their mutual histories. Part one provides a historical context for the current movement using the example of the development and deployment of the smallpox vaccine as a representative timeline of vaccine acceptance and opposition. Part two describes the current movement in the United States and the United Kingdom, interprets the reasons for the conclusions drawn by vaccine-concerned parents, and provides a framework for public health officials to approach the issues.
ContributorsKost, Stephanie Michelle (Author) / Lynch, John (Thesis director) / Hurlbut, Ben (Committee member) / Robert, Jason (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor) / School of Life Sciences (Contributor)
Created2013-12
Description
Dengue virus infects millions of people every year. Yet there is still no vaccine available to prevent it. Here we use a neutralizing epitope determinant on the dengue envelope (E) protein as an immunogen to be vectored by a measles virus (MV) vaccine. However the domain III (DIII) of the dengue 2 E protein is too small to be immunogenic by itself. In order for it to be displayed on a larger particle, it was inserted into the amino terminus of small hepatitis B surface antigen (HBsAg, S) coding sequence. To generate the recombinant MV vector and verify the efficiency of this concept, a reverse genetics system was used where the MV vectors express one or two additional transcription units to direct the assembly of hybrid HBsAg particles. Two types of recombinant measles virus were produced: pB(+)MVvac2(DIII-S,S)P and pB(+)MVvac2(DIII-S)N. Virus recovered from pB(+)MVvac2(DIII-S,S)P was viable. An ELISA assay was performed to demonstrate the expression and secretion of HBsAg. Supernatant from MVvac2(DIII-S,S)P infected cells confirmed that hybrid HBsAg-domain III particles with a density similar to traditional HBsAg particles were released. Characteristics of the subviral particle have been analyzed for the successful incorporation of domain III. The replication fitness of the recombinant MV was evaluated using multi-step growth kinetics and showed reduced replication fitness when compared to the parental strain MVvac2. This demonstrates that viral replication is hindered by the addition of the two inserts into MV genome. Further analysis of MVvac2(DIII-S)N is needed to justify immune response studies in a small animal model using both of the generated recombinant vectors.
ContributorsHarahap, Indira Saridewi (Author) / Reyes del Valle, Jorge (Thesis director) / Hogue, Brenda (Committee member) / Misra, Rajeev (Committee member) / Barrett, The Honors College (Contributor) / T. Denny Sanford School of Social and Family Dynamics (Contributor) / School of Human Evolution and Social Change (Contributor) / School of Life Sciences (Contributor)
Created2014-05
Description
Vaccinations are important for preventing influenza infection. Maximizing vaccination uptake rates (80-90%) is crucial in generating herd immunity and preventing infection incidence. Vaccination of healthcare professionals (HCP) against influenza is vital to infection control in healthcare settings, given their consistent exposure to high-risk patients like: those with compromised immune systems, children, and the elderly (Johnson & Talbot, 2011). Though vaccination is vital in disease prevention, influenza vaccination uptake among HCP is low overall (50% on average) (Pearson et al., 2006). Mandatory vaccination policies result in HCP influenza vaccination uptake rates substantially higher than opt-in influenza vaccination campaigns (90% vs. 60%). Therefore, influenza vaccination should be mandatory for HCP in order to best prevent influenza infection in healthcare settings. Many HCP cite individual objections to influenza vaccination rooted in personal doubts and ethical concerns, not best available scientific evidence. Nevertheless, HCP ethical responsibility to their patients and work environments to prevent and lower influenza infection incidence overrules such individual objections. Additionally, mandatory HCP influenza vaccination policies respect HCP autonomy via including medical and religious exemption clauses. While vaccination as a prevention method for influenza is logically sound, individuals’ actions are not always rooted in logic. Therefore, I analyze HCP perceptions and actions toward influenza vaccination in an effort to better explain low HCP uptake rates of the influenza vaccine and individual objections to influenza vaccination. Such analysis can aid in gaining HCP trust when implementing mandatory HCP influenza vaccination policies. In summary, mandatory HCP influenza vaccination policies are ethically justified, effective, scientifically-supported method of maximizing HCP influenza vaccine uptake and minimizing the spread of the influenza virus within healthcare settlings.
ContributorsGur-Arie, Rachel (Author) / Maienschein, Jane (Thesis advisor) / Hurlbut, Ben (Thesis advisor) / Ellison, Karin (Committee member) / Arizona State University (Publisher)
Created2016
Description
Despite the approval of a Dengue virus (DV) vaccine in five endemic countries, dengue prevention would benefit from an immunization strategy highly immunogenic in young infants and not curtailed by viral interference. Problematically, infants younger than 9 year of age, whom are particularly prone to Dengue severe infection and death, cannot be immunized using current approved DV vaccine. The most important issues documented so far are the lack of efficiency and enhancement of the disease in young seronegative recipients, as well as uneven protection against the four DV serotypes. Based on data from clinical trials that showed enhanced performance of dengue vaccines when the host has previous anti-flaviviral immunity, I proposed here an attractive solution to complement the current vaccine: a recombinant measles vaccine vectoring dengue protective antigens to be administered to young infants. I hypothesized that recombinant measles virus expressing Dengue 2 and 4 antigens would successfully induce neutralizing responses against DV2 and 4 and the vaccine cocktail of this recombinant measles can prime anti-flaviviral neutralizing immunity. For this dissertation, I generated and performed preclinical immune assessment for four novel Measles-Dengue (MV-DV) vaccine candidates. I generated four MVs expressing the pre membrane (prM) and full length or truncated (90%) forms of the major envelope (E) from DV2 and DV4. Two virus, MVvac2-DV2(prME)N and MVvac2-DV4(prME), expressed high levels of membrane associated full-length E, while the other two viruses, MVvac2-DV2(prMEsol)N and MVvac2-DV4(prMEsol)N, expressed and secreted truncated, soluble E protein to its extracellular environment. The last two vectored vaccines proved superior anti-dengue neutralizing responses comparing to its corresponding full length vectors. Remarkably, when MVvac2-DV2/4(prMEsol)N recombinant vaccines were combined, the vaccine cocktail was able to prime cross-neutralizing responses against DV 1 and the relatively distant 17D yellow fever virus attenuated strain. Thus, I identify a promising DV vaccination strategy, MVvac2-DV2/4(prMEsol)N, which can prime broad neutralizing immune responses by using only two of the four available DV serotypes. The current MV immunization scheme can be advantageus to prime broad anti-flaviviral neutralizing immunity status, which will be majorly boosted by subsequent chimeric Dengue vaccine approaches.
ContributorsAbdelgalel, Rowida (Author) / Reyes del Valle, Jorge (Thesis advisor) / Mason, Hugh (Thesis advisor) / Lake, Douglas (Committee member) / Stout, Valerie (Committee member) / Frasch, Wayne (Committee member) / Arizona State University (Publisher)
Created2016