An effective HIV-1 vaccine will likely elicit broadly neutralizing antibodies (bnAbs). However, development of vaccine immunogens that induce bnAbs remains a challenging goal. Understanding the somatic maturation pathways of known broadly neutralizing HIV-1 human monoclonal antibodies (bnmAbs) may help vaccine immunogen design. All known HIV-1 bnmAbs are highly somatically matured, and the putative germline antibodies of the known HIV-1 bnmAbs lack measurable binding activity to HIV-1 envelope glycoprotein (Env). Based on these observations, we hypothesize that somatic maturation of known HIV-1 bnmAbs may be initiated by primary immunogens which may not be related to HIV-1 Env; such primary immunogens trigger the somatic maturation of the germline antibodies and induce intermediate antibodies that bind to HIV-1 Env and further mature to bnAbs upon HIV-1 infection or Env vaccination. The main objective of my study is to identify intermediate antibodies of bnmAb b12 in uninfected and infected human individuals, as well as in uninfected rhesus macaques, the model animals for vaccine development. I constructed two nonimmune cDNA antibody VH1 scFv libraries using the mRNAs isolated from pooled PBMCs of 200 uninfected healthy human individuals and one uninfected rhesus macaque, respectively, and identified 5 and 10 possible b12 intermediate immunoglobulin heavy chain V-segments (IGHVs) from the human and macaque nonimmune libraries, respectively. 454 deep sequencing of the VHs and VLs in the nonimmune and two immune human cDNA Fab libraries confirmed the existence of b12 intermediate IGHVs, but we did not find further maturation of the b12 intermediate IGHVs in HIV-1-infected human individuals. Further sequence analysis revealed the extremely low frequency of the VHs with exactly the same V(D)J recombination as b12, which may explain the lack of further maturation of the intermediate IGHVs of b12 in HIV-1-infected humans. Characterization of HIV-1 Env trimer may aid in Env-based vaccine immunogen design. Therefore, I investigated the importance of Env variable loops in Env-mediated viral function. A panel of gp160JRFL loop deletion/replacement mutants were constructed and tested. The results indicate that, besides the CD4 binding loop and V3, V1V2 and loop D are also critical for virus entry into permissive cells. Deletion of variable V4 or V5 loop or replacement of V4 or V5 loop with a flexible linker of the same length abolish Env cell surface display, which may result from the conformational changes of the V4 or V5 loop deletion or replacement Env proteins. V4 or V5 deletion or replacement knocks out the CD4 binding site and CD4-induced site on Env, but enhances the exposure of the membrane-proximal external region (MPER) and N-trimer structure. In summary, my study demonstrated the existence of intermediate b12 IGHVs in uninfected and HIV-1-infected humans and rhesus macaques. These intermediate antibody fragments may be used to identify primary immunogens that initiate b12 somatic maturation. My study also showed the importance of Env variable loops for Env structural integrity and Env-mediated viral function. The enhanced exposure of the MPER in gp160JRFL ΔV4 or ΔV5 may be further explored for vaccine development to induce MPER-specific bnAbs. / published_or_final_version / Microbiology / Doctoral / Doctor of Philosophy

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An imbalance of the oxidant-antioxidant equilibrium has been associated with disease progression in HIV-seropositive individuals. In vitro and in vivo studies have demonstrated the efficacy of antioxidant supplementation in reducing the concentrations of oxidative stress markers. The objectives of the present cross-sectional study were to evaluate the dietary intake and nutritional supplementation practices of 24 HIV-seropositive persons in Montreal and explore the relationship between dietary intakes of antioxidant micronutrients (ascorbic acid, vitamin E, $ beta$-carotene, zinc, selenium), oxidative stress (plasma malondialdehyde (MDA), leukocyte glutathione (GSH)) and immunological indices (absolute CD4+ counts, polymorphonuclear leukocytes (PMN)). Unexpectedly, and paradoxically, a tendency to higher MDA concentrations in subjects with higher CD4+ counts was observed (r = 0.39, p $<$ 0.10). Moreover, supplementation with vitamin E was associated with significantly higher MDA concentrations (p $<$ 0.05). Ascorbic acid intake, even at levels in excess of the tissue saturation (200 mg/d) did not significantly lower MDA concentrations. Neither GSH concentrations nor CD4+ counts were significantly different between supplement users and non-users. In general, the small sample size of this study may have been in part responsible for the failure to detect statistical significance in some associations, however, trends were noted. These included the observation that vitamin supplement users were more likely to have a history of a clinical event associated with HIV infection (opportunistic infection, neoplasm, unintentional weight loss), have a longer duration of IV-seropositivity and have significantly higher MDA concentrations (p $<$ 0.05). In this study, it appears that antioxidants, and vitamin E in particular, were ineffective in reducing the elevated levels of reactive oxygen species (ROS) associated with HIV infection.

This study investigates the coping methods, styles and strategies of 35 homosexual men who are infected with the human immunodeficiency virus (HIV) but remain asymptomatic. Subjects were recruited from a Montreal AIDS clinic and support groups for men with HIV. The effectiveness of the coping mechanisms were evaluated by correlating these to measures of depression, state and trait anxiety, psychosomatic symptomatology, perceived social support and global health. Data analyses revealed that men with HIV infection were generally well-adjusted and employed a variety of coping techniques. Cognitive attempts at coping were the most frequently used and were related to elevated levels of state and trait anxiety and poorer global health. Perceived social support proved to be an important determinant of global health, and a buffer for anxiety. Religious identity was related to an enhanced perception of social support, while individuals who had sought counselling were reported to be more anxious and in poorer health. Finally, education level was related to the development of effective and diverse coping methods, styles and strategies. The implication of these results and suggestions for further research are discussed.

Purpose: The aim was to determine the echocardiographic features of patients with infective endocarditis, and to compare the findings in HIV positive versus HIV negative patients. Methods: This was a prospective study, conducted over three years using the modified Duke criteria in diagnoses. A control group of age-matched patients with clinical and echocardiographic evidence of valvular regurgitation, who did not satisfy the criteria and who underwent surgery was used in comparison. Results: During this period 91 patients were screened for infective endocarditis. 77 satisfied the criteria for a definite diagnosis of IE. Blood cultures were positive in 46% cases. The commonest organism was S. aureus. Most patients had advanced valve disruption with heart failure and a high peri-operative mortality. The clinical features in the two groups of patients was similar. The incidence of echocardiographic complications was 50.6% in the whole group. Except for leaflet aneurysms in four HIV positive cases, complications were not more frequent in this group. Conclusion: There was a high rate of culture negative cases in this study, probably related to prior antibiotic usage; in this setting the modified Duke criteria have diagnostic limitations. There was no difference in the clinical presentation of infective endocarditis between HIV positive and HIV negative patients. Leaflet aneurysms were more common in the HIV positive patients. / Thesis (M.Med.)-University of KwaZulu-Natal, 2008.

Every day more people in Africa are infected with HIV despite prevention efforts. These new infections and those already infected are not evenly spread throughout the continent. Substantial variations in HIV prevalence exist within and between countries. Understanding these variations helps understand what is driving the epidemic and this understanding in turn helps in the design of more appropriate interventions to prevent its further spread. This thesis builds on existing work by attempting to develop a more comprehensive theory of what role income plays in the spread of HIV. To this end the Theory of the Dual Role of Income in the Spread of HIV is outlined and explained. It uses the concepts of relative and absolute income, borrowed from elsewhere in the health economics literature, to separate the different effects income has on individual and group risk of HIV infection. The theory hypothesises that, while higher levels of absolute income (income independent of others) offer protection against infection via better access to health care and information, higher relative income (the income of an individual relative to other members of their social or reference group) increases risk of infection either as a result of more sexual partners or higher risk partners. The theory in no way argues that HIV infections are not related to poverty, but rather that the relationship is, somewhat more complicated and non-linear than often suggested. The explanatory power of the theory is examined with the use primarily of two data sets: firstly using data collected from antenatal clinics in two South African provinces linked with census data and secondly with data on a large South African company. While these data are not ideal, the results from the analysis are in line with the expectations based on the theory. The theory and the results of the analysis presented in this thesis support the argument that environments in which decisions are made and actions taken are important in determining risk of HIV infection. This argument suggests that prevention efforts need to do more then provide information. / Thesis (M.Com.)-University of Natal, Durban, 2002.

Abstract not available. / Thesis (M.Med.Sc.)-University of KwaZulu-Natal, 2008.

Infection with HIV-2 has important implications for the diagnosis, treatment and management of the infection. The objective of this study was to describe the seroprevalence and molecular epidemiology of HIV-2 in KwaZulu-Natal – the province with the highest HIV prevalence in South Africa, which in turn is the country with the highest HIV prevalence in the world. HIV-1 positive samples were screened using a rapid test for HIV-2. Samples showing antibody positivity were subject to molecular confirmation by PCR and / or serological confirmation by Western blot. There was a large difference in results (10.6% by Western blotting versus 0% by PCR). This discrepancy between molecular and serological confirmation by Western blot. There was a large difference in results (10.6% by Western blotting versus 0% by PCR). This discrepancy between molecular and serological confirmation was attributed to cross-reacting antibodies. The use of rapid tests and Western blots for HIV-2 diagnosis in South Africa, should, therefore, be interpreted with caution. Based on the results of this study, HIV-2 is most probably not present in KwaZulu-Natal. / Thesis (M.Med.Sc.)-University of KwaZulu-Natal, Durban, 2013.