Thesis (Ph. D.)--University of Washington, 1996. / Includes bibliographical references (leaves [213]-237).

Thesis (Ph. D.)--Ohio State University, 2009. / Title from first page of PDF file. Includes vita. Includes bibliographical references (p. 217-241).

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 93-109).

M.Sc. / Therapeutic and preventative treatment are continually being sought to cease or curtail the worldwide HIV-1 epidemic. At present, therapeutic drug strategies such as highly active anti-retroviral therapy (HAART) have been particularly successful in slowing disease progression and reducing the incidence of AIDS and AIDS related mortality (Detels et al., 1998; Mocroft et al., 1998; Palella et al., 1998). However, the high costs, intricate dosing regimens and limited availability of the HAART drugs (Butera, 2000) has restricted its efficacy in developing and third world countries. As such, available and future drugs will remain inaccessible to the regions that are profoundly affected by the epidemic. An effective vaccine presents a viable solution to the HIV-1 epidemic in these countries. Approximately 70 vaccines are presently in various stages of clinical trials, the majority of which are subtype B specific (Johnston and Flores, 2001). This prevents their use in the predominantly subtype C infected sub-Saharan region of Africa, which accounts for 50% of the global HIV / AIDS population and includes South Africa, statistically the country with the highest number of people living with HIV / AIDS of any country in the world (UNAIDS, 2002). Presently there is no HIV-1 vaccine, regardless of subtype, in clinical use. This owes to several difficulties that hinder the progression of vaccine development, including the lack of predictive animal models, the establishment of viral latency and the difficulty involved in overcoming HIV-1 genetic diversity (Klein, 1999). The expansive HIV-1 genetic variation exhibited by HIV-1 is attributed to a high number of errors made by the reverse transcriptase (RT) enzyme (Coffin, 1992) and the absence of RT proofreading mechanisms during HIV-1 replication (Roberts et al., 1988; Bebenek et al., 1989). The HIV-1 nucleotide sequence drift is most frequently observed in the envelope (env) gene and expressed in env gene products (Shafer et al., 1999). Expression of the variable genome results in the production of progeny strains that are not identical to the parent strain (i.e. HIV-1 exists as a quasispecies within each seropositive individual and between individuals) and contributes to the diverse collection of viral strains in global circulation that vary across and within subtypes. Thus, for an HIV-1 vaccine to be efficient and truly functional it would be required to target this observed hypervariability and be effective against a multitude of currently circulating strains, exhibit cross-clade specificity and remain viable despite the emergence of variant strains. In this study we describe the design, synthesis and immunological ability of a multiple epitope immunogen (MEI) that mimics the hypervariability observed within the third variable (V3) loop of the envelope gp120 region of HIV-1 subtype C. Conjugation to a multiple antigenic peptide (MAP) produces a four -branched (b4) tetrameric peptide construct, designated MEIV3b4. This construct was characterized by theoretical and analytical techniques, tested in a variety of immunological assays and assessed for its potential as a candidate vaccine component. The construct was comparatively analysed through evaluation of three comparison peptides, two of which are hypervariable and based on the V3 region, the other representing a conserved region of HIV-1 envelope. The V3 peptides, named b-MEI-s and poly-L-MEI, differ from the MEIV3b4 construct in that they are less variable and less branched or conjugated to a traditional carrier rather than to a MAP system, respectively. The conserved peptide, designated CCD4 allowed for comparative evaluation between conserved and variable peptides as potential vaccine components. / Dr. Debra Meyer

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2002. / Härtill 6 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

Thesis (MSc (Psychology))--University of Stellenbosch, 2006. / HIV vaccines are currently being developed and tested worldwide. This thesis reports on a qualitative study that was conducted to determine the concerns and problems regarding participation in future HIV vaccine trials. The sample for the study was selected from a peri-urban township, Masiphumelele, in Cape Town, Western Cape province, South Africa. The HIV-prevalence rate in Masiphumelele is 25%. A total of 10 participants between the ages of 19 and 30 were recruited for the present study. All participants’ first language was Xhosa and seven of them had English as a second language. Owing to a language barrier, an interpreter assisted the interviewer in conducting the interviews in the preferred language of the participants. Participants were recruited by convenience sampling and were asked to participate in two semi-structured interviews, under confidential conditions. The first interview addressed knowledge regarding HIV/AIDS, HIV vaccines and HIV clinical trials. The second interview identified the concerns and problems participants had regarding participation in future HIV vaccine trials. The interviews were recorded, transcribed and entered into Atlas ti., a computer program that assists in the analysis of textual data. The analysis of the data focused on the content of participants’ concerns about barriers to participation and their perspectives on facilitators to participation. The data collected on concerns and problems which, may influence participants’ willingness to participate in future HIV vaccine trials, was divided into two overarching themes, namely, barriers to participation and facilitators to participation. The barriers to participation included physical symptoms, stigma and discrimination, trypanophobia, distrust, psychological distress, sexual disinhibition and family responsibilities. The facilitators to participation included altruism, own protection from HIV infection, hopefulness, medical incentives, determining of HIV status, acquisition of knowledge, and equal treatment of participants in the experimental group and the placebo control group resulting from a double-blinded randomised trial. The question of participants’, recruited in the present study, willingness to participate in a future HIV vaccine trial are discussed in terms of Bronfenbrenner’s (1979) theoretical work on ecological systems, the social learning theory and the Health Belief Model (HBM). These theoretical frameworks deal with individuals, their behaviour and their environment, and how these influence one another. The significance and future direction of this line of research helps to overcome the barriers to participation and enhance the facilitators to participation. Thus, the intended result of such efforts is to maximise individuals’ participation in future HIV vaccine trials.

Thesis (MSCMedSc (Pathology. Medical Virology))--University of Stellenbosch, 2005. / There is an urgent need for a safe, effective, affordable human immunodeficiency virus type 1 (HIV-1) vaccine that induces both cellular and humoral immunity. A popular strategy for vaccine design is the use of plasmid DNA encoding HIV-1 genes for priming vaccinations followed by either viral vector or recombinant protein boosting. DNA-based vaccines are attractive because they are safe, easily administered and can induce both cellular and humoral immune responses. In order for DNA vaccination to induce a potent immune response it is necessary for plasmid-encoded genes to be targeted to dendritic cells (DCs) as these are the key antigen presenting cells in natural HIV infection. The immunogenicity of all potential vaccine candidates needs to be assessed in animal models prior to entry into human trials. Nonhuman primates are the best alternative to humans for assessment of vaccine immunogenicity and protective efficacy. In order to clearly understand how DNA vaccines interact with DCs, suitable in vitro DC culture systems for nonhuman primates need to be developed. This study investigated the culture and characterisation of chacma baboon DCs in vitro, and was the first to assess the effect of various transfection methods on baboon DC maturation and function. The study also evaluated the efficacy of a candidate HIV-1 subtype C DNA vaccine at the level of baboon DC transfection, gene transcription and antigen presentation. Generation of immature DCs (iDCs) in the presence of interleukin-4 (IL-4) and granulocyte-macrophage colony stimulating factor (GM-CSF) was accompanied by a loss in the monocyte marker CD14. Expression of the markers CD80 and CD83 was observed on a minority of iDCs, whereas CD86 was expressed on almost all iDCs. Following maturation, all these markers were expressed on an increased number of cells, a pattern of marker expression and upregulation that is similar to that observed in both human and macaque DCs. Transfection of baboon DCs by passive pulsing, lipofection and electroporation was evaluated and compared in several ways. Transfection efficiency, cytotoxicity, the effect of the transfection on DC maturation and subsequent presentation of plasmidencoded antigen to memory T lymphocytes was examined. Baboon DCs lipofected with pDNA efficiently took up HIV-1 subtype C plasmid DNA, transcribed plasmid-encoded genes into mRNA, translated the mRNA into protein, processed the protein and presented peptide antigens to antigen-specific memory T cells. The other methods of transfection were less effective than lipofection due to either decreased transfection efficiency or increased cell cytotoxicity. However, neither lipofection nor passive pulsing in any way negatively impacted on DC marker, CD83, or costimulatory molecule, CD80 and CD86, upregulation. Both methods were found to be as effective as a standard cytokine maturation cocktail in inducing DC maturation. Transfected DCs were also found to be more potent inducers of allogeneic T cell stimulation than their untransfected counterparts, which would appear to indicate enhanced major histocompatibility complex (MHC) expression concurrent with DC maturation marker expression. Lipofection with candidate HIV-1 subtype C vaccine plasmid DNA constructs led to antigen-specific expansion of autologous memory T cells, a finding which indicates the effective expression of plasmid-encoded HIV genes in baboon DCs. This study highlights the functional activity of in vitro generated baboon DCs and provides the groundwork for future studies addressing targeting of plasmid DNA to DCs and enhancement of expression of plasmid-encoded antigens in DCs. A more detailed evaluation of baboon DC interaction with simian immunodeficiency viruses/chimeric simian human immunodeficiency viruses (SIVs/SHIVs) may also reveal how the course of infection in this primate differs from that seen in the macaque or chimpanzee and also how it relates to HIV-1 infection in humans.

Thesis (PhD)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Background South Africa is the country with the largest number of HIV infections in the world. As behaviour change initiatives have been suboptimal in curbing the spread of the pandemic, an HIV vaccine is likely to be an important development as a biological agent may circumvent some of the challenges of initiating widespread behaviour change. The development of an HIV vaccine will require several thousands of HIV negative participants who are at high risk of HIV infection to participate in HIV vaccine clinical trials. Before recruitment for such trials may begin, various scientific, ethical, and sociobehavioural issues need to be considered. One of the key sociobehavioural issues concerns the willingness of individuals at high risk of HIV infection to participate in HIV vaccine trials. However, a psychometric measure of willingness to participate (WTP) has not been constructed, and there is a paucity of theory to guide studies of WTP. Objectives The first objective of this study was to construct a psychometric measure of WTP in an HIV vaccine trial, and to derive the exploratory factor structure of the measure. The second objective was to examine the extent to which the Theory of Planned Behavior (TPB) could predict variance in WTP, and to determine whether the TPB was strengthened by the inclusion of mistrust of researchers, knowledge of HIV vaccines and HIV vaccine trials, altruism, and perceived risk of HIV infection as additional predictor variables. Methodology This study was a research survey with a cross-sectional design. A convenience sample of 399 participants was recruited from an urban-informal settlement near Cape Town. As 79 of the questionnaires were poorly completed, the final sample size was 320. To develop a measure of WTP in an HIV vaccine trial, an item pool was developed whereby items directly reflected inhibitors and facilitators of WTP. After an iterative process of refinement, the final scale consisted of 35 items and was named the Willingness to Participate Scale (WTPS). A principal component Kaiser normalised exploratory factor analysis (EFA) was conducted on the items that constituted the WTPS. This procedure was performed to identify latent factors which were informed by the items of the scale. To test the predictive capacity of the TPB and the additional predictor variables, a two-step linear hierarchical multiple regression analysis was performed. At step 1, the TPB variables were entered simultaneously. At step 2, the TPB variables along with the additional predictor variables were entered simultaneously. Results The WTPS demonstrated excellent internal consistency (α = 0.90) and initial construct validity, as evidenced by the presence of seven latent factors. The factors accounted for 53.15% of the variance in WTP and were: (i) Social approval and trust; (ii) Stigmatisation; (iii) Personal costs; (iv) Personal gains; (v) Personal risks; (vi) Convenience; and (vii) Safety. The TPB significantly accounted for 6.4% (R² = 0.06) of the variance in WTP [F(3, 316) = 7.16, p < 0.001], yielding a small effect size (ƒ2 = 0.06). The TPB, together with mistrust, knowledge of HIV vaccines and HIV vaccine trials, altruism, and perceived risk of HIV infection as additional predictor variables significantly accounted for 10.2% (R² = 0.10) of the variance in WTP [F(7, 312) = 5.06, p < 0.001], yielding a small to medium effect size (ƒ2 = 0.11). Subjective norms, mistrust of researchers, altruism, and perceived risk of HIV infection were significant independent predictors of WTP. Conclusion Against the backdrop of the study limitations, the results of this study provide initial support for the reliability and construct validity of the WTPS among the most eligible trial participants in the Western Cape of South Africa. The findings also suggest that the TPB may not be an appropriate theoretical framework for predicting WTP in an HIV vaccine trial in this context. Nonetheless, normative pressure by others, mistrust of researchers, altruism, and perceived risk of HIV infection may influence WTP in this population. Implications for future research are discussed. / AFRIKAANSE OPSOMMING: Agtergrond Suid afrika is die land met die hoogste getal HIV infeksies in die wêreld. Vir die ontwikkeling van 'n HIV entstof, sal daar vereis word dat duisende HIV negatiewe deelnemers, wat 'n hoë risko kans staan om HIV infeksie op te doen, moet deelneem aan 'n kliniese HIV vaksine proeftog. Verskeie, wetenskaplike, etiese en sosiale gedrags punte moet oorweeg word, voor die werwing van sulke proefnemings. Een van die hoof aspekte van sosiale gedrags punte is die bereidwillgheid van 'n individu om blootgestel te word aan die HIV infeksie tydens die proeftog. 'n Psigometriese skatting van bereidwiligheid om deel te neem (BODTN) is egter nog nie gekonstruktureer nie en daar is 'n skaarste/geringheid in studies om as gids te dien vir die BODTN. Doel Die eerste doel van hierdie studie was om 'n psigometriese skatting van BODTN in ’n HIV vaksiene proefneming te konstruktureer, en om die ondersoekings oorsaak/faktor struktuur daarvan te meet en af te lei. Die tweede doel was om ondersoek in te stel of die omvang van die Teorie van Beplande Gedrag (TBG) verskille kan voorspel in die BODTN, en om vas te stel of die TBG versterk word deur die insluiting van wantroue in navorsers, kennis van HIV vaksienes en HIV vaksiene proefnemings, altruïsme, en die begrypbare risko van HIV infeksie as adisionele voorspellers. Metode Hierdie studie is 'n navorsings ondersoek met 'n deursneeproef ontwerp. ’n Grieflike aantal van 399 deelnemers was gewerf van 'n informele nedersetting naby Kaapstad. Die finale getal was 320 omdat 79 nie die vraelys korrek on volledig ingevul het nie. Na 'n interaktiewe proses van suiwering/verfyning, het die finale skaal uit 35 items bestaan en word die skaal benoem na die Willingness to Participate Scale (WTPS). Die prinsipale komponent Kaiser normaliseer EFA wat gedoen was op die items wat die WTPS konstitueer. Hierdie prosedure was gedoen om die latente faktore te identifiseer wat beskikbaar gestel was deur die items van die skaal. Om die voorspelbare kapasiteit van die TBG en die adisionele voorspelbare verskille te toets, het ons 'n twee stap hiërargiese veelvoudige agteruitgaan analise gebruik. By stap 1 was die TBG veranderlikes gelyktydig ingedruk. By stap 2 is die TBG veranderlikes tesame met die adisionele voorspellers in gedruk. Resultate Die WTPS het uitstekende interne konsistensie en 'n aanvanklike geldigheid gedemonstreer, soos bewys deur die teenwoordigheid van die 7 latente faktore. Die faktore verantwoord 53.15% van die verskil in WTP en was: (i) Sosiale aanvaarding en vertroue; (ii) Stigma; (iii) Persoonlike koste; (iv) Persoonlike wins/profyt; (v) Persoonlike risiko's; (vi) Gerieflikheid; en (vii) Veiligheid. Die TBG verantwoord 6.4% (R²=0.06) van die verskil in BODTN [F(3.316) = 7.16, p<0.001] met 'n toegewende klein groote uitwerking/uitslag. Die TBG tesame met wantroue, kennis van HIV vaksienes en HIV vaksiene proefnemings, altruïsme, en begrypbare risko van HIV infeksie as adisionele voorspellers, verwantwoord 10.2% (R²=0.10) van die verskil in BODTN [F(7.312 = 5.06, p<0.001], met 'n toegewende klein tot medium groote uitwerking/uitslag (f²=0.11). Subjektiewe norme, wantroue in navorsers, altruïsme, en 'n beprypbare risko van HIV infeksie was betekenisvolle, onafhanklike voorspellers van die BODTN. Gevolgtrekking Teen die agtergrond van die studie beperkinge, het die resultate van hierdie studie ondersteuning voorsien aan die vertroubaarheid en konstruktiewe geldigheid van die WTPS onder die mees geskikste proef deelnemers in die Wes Kaap van Suid Afrika. Die bevinding stel ook voor dat die TBG nie altyd 'n geskikte teoretiese raamwerk is vir die voorspelling van die BODTN in 'n HIV vaksiene proefneming in hierdie konteks is nie. Des nie teen staande, normale druk van ander, wanrtroue in navorsers, altruïsme en die begrypbare infeksie van HIV kan die populasie deur die BODTN beinvloed word. Implikasies vir toekomstige navorsing is bespreek.

To date, the HIV/AIDS pandemic remains a global disaster. The sheer scale of the pandemic and the limited success of prevention programmes in controlling its spread have necessitated an urgent need for the development of a safe, effective and affordable HIV preventive vaccine. However, perceptions of HIV vaccines and the relationships between HIV/AIDS knowledge, perceived risk and existing views on HIV vaccines are minimum characteristics required to make future HIV vaccines a worthwhile public health tool. This study reports findings among representatives of the ethnic groups aged between 18 and 49 in the Rustenburg community of Bojanala district (N = 351). The study utilized some of the data collected by the Aurum Institute of Health Research representative household survey that forms part of a range of HIV vaccine preparedness studies in the Bojanala area, Rustenburg. Descriptive statistics were applied to all items. Independent samples T- tests and Analysis of variances (ANOVAs) were used to compare means. Correlational statistics (Pearson‘s product moment) was used to explore relationships between pairs of variables. A standard multiple regression analyses was applied to assess and explore the factor(s) that predict the likelihood that respondents would report supportive perceptions for HIV vaccines while the hierarchical model fitted was done to control for the influence of demographic variables. About 74% of the study participants had good knowledge of HIV/AIDS-related issues and the same percentage of respondents identified self and their community to be at risk of HIV/AIDS infection (measured as fatalism regarding risk of contracting HIV infection). Positive view-points regarding participation in vaccine trials and belief in a future HIV vaccine to protect from contracting HIV infection was reported by almost 90% of the study participants. Meanwhile, a majority (60%) had low levels of knowledge on HIV vaccines. The results of standard and hierarchical multiple regressions showed that knowledge on HIV/AIDS transmission, prevention and treatment (in particular) are the best predictors of perceptions of an HIV vaccine. Furthermore, with the exception of the duo of perceived HIV risk and perceptions of HIV vaccine, positive correlations were found among knowledge, perceived HIV risk and vaccine perceptions, as well as among these and exposure to the media. Race (being Black in particular) and low levels of education seem to be profound challenges facing HIV/AIDS related issues, particularly perceived HIV risk. The findings from this study have implications for strategies in HIV prevention, viz. education, service delivery, advocacy and policy among others at institutional, national, regional, and global level in both public and private sectors. Political will, unprecedented collaborative effort among stakeholders and review of the existing Expanded Programme of Immunization schedule are all required to make the future HIV vaccine globally available. In addition, deductions highlight several key areas where research is urgently needed. / Thesis (M.A.)-University of KwaZulu-Natal, Durban, 2010.