Defining HIV persistence and host immune responses in lymph nodes of combined antiretroviral therapy (cART) suppressed individuals and the determination of the impact of HIV infection on SARS-COV-2 specific t cell responses in South Africa = Ukuchazwa kokuphikelela kwe-HIV kanye nokulwisana nayo kwamasosha okwelashwa ngemishanguzo exubile eyaziwa nge-cART okubonakala ezimbilaphweni kubantu abangakhombisi ukuthi banegciwane le-HIV, kanye nokuvela kwemithelela yokutheleleka ngegciwane le-HIV ekulweni kwamaseli awuhlobo lwe-T kwi-SARS-CoV-2 eNingizimu Afrikha.

Abstract

Abstract 1 People living with HIV (PLWH) who have unsuppressed HIV are at a greater risk of acquiring infectious diseases such as Coronavirus disease of 2019 (COVID-19). More recent data has shown that unsuppressed HIV is associated with severe COVID-19 symptoms, but the mechanisms underpinning this susceptibility are still unclear. In our study we used flow cytometry and culture T lymphocyte expansion to assess the impact of HIV infection on the quality and epitope specificity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) T cell responses in the first wave and second wave of the COVID-19 epidemic in South Africa. We observed that HIV-seronegative individuals had significantly greater CD4+ T cell responses against the Spike protein compared to the viremic individuals living with HIV. In addition, there was diminished T cell cross-recognition between the two waves, which was more pronounced in individuals with unsuppressed HIV infection. Importantly, we identified four mutations in the Beta variant that resulted in the abrogation of T cell recognition. These findings partly explain the increased susceptibility of PLWH to diseases such as COVID-19 and highlight their vulnerability to emerging SARS-CoV-2 variants of concern.

Abstract 2 The major keys to developing an HIV cure is through understanding HIV reservoir dynamics. The role of tissue macrophages in HIV reservoirs is complex and not yet fully understood. However, their ability to support viral replication, longevity, localization in immune sanctuaries, and potential for viral latency all contribute to the persistence and resilience of HIV reservoirs in various tissues throughout the body. Understanding and targeting these reservoirs is a critical area of research in the quest for an HIV cure. To gain insight into the macrophage reservoir, we used a combination of flow cytometry and immunofluorescence microscopy to characterize and investigate HIV persistence in lymph node (LN) macrophages. We detected pro-inflammatory (CD68+ ) macrophages harboring HIV Gag p24 and HIV1 RNA in the germinal centers of HIV positive early and late treated individuals suggesting their potential role as an HIV reservoir. In contrast, anti-inflammatory (CD206+ ) macrophages were localized along lymphatic vessels and outside the germinal centers. Importantly, we show the presence of longlived CD4+ TIM-4+ macrophages in LNs. The data reported in this thesis will go a long way in furthering our understanding of macrophage HIV reservoirs in lymph node macrophages.

Iqoqa 1. Abantu abaphila ne-HIV (PLWH) abakhombisayo ukuthi bane-HIV basengozini enkulu yokuthola izifo ezithathelwanayo njenge-Coronavirus ka-2019 (COVID-19). Imininingo yakamuva ibonise ukuthi i-HIV ebonakalayo ihlotshaniswa nezimpawu ezinzima ze-COVID-19, kodwa izindlela ezisekela lokhu kuba sengozini azikacaci. Ocwaningweni lwethu siqale sasebenzisa i-flow cytometry kanye nokwandiswa kokuhlolwa kwamaseli egazini angamasosha okulwisana nezifo ukuze kubonakale umthelela wokuchaphazeleka nge-HIV kwikhwalithi nokucaciswa kokuvela kwezimpawu zezinkinga zokuphefumula kanzima ze-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) kanye nendlela amaseli ayi-T cell alwa ngayo ekugaseleni kuqala kanye nokwesibili kobhubhane lwe-COVID-19 eNingizimu Afrika. Siqaphele ukuthi abantu abangenalo igciwane le-HIV, amaseli abo ayi- CD4+ T ayelwa ngendlela enamandla amakhulu ngokumelene ne-Spike protein uma kuqhathaniswa nabantu abanegciwane egazini abaphila ne-HIV. Ukwengeza, kube nokuncipha kokuqashelwa kwe-T cell phakathi kwalezi ziwombe zokugasela ezimbili, okwakubonakala kakhulu kubantu abane-HIV engacashile. Okubalulekile, sihlonze izinguquko ezine kwi-DNA yo hlobo lwe-Beta okuholele ekucindezelekeni kokusebenza kweseli ye-T. Imiphumela ichazile nakuba kungaphelele ukuhlaseleka kwe-PLWH ezifweni ezinjenge-COVID-19 kanti futhi kugqamisa nokuba sengozini kwabo kwezinye izinhlobo ze-SARS-CoV-2 ezisaqubuka ngendlela eyethusayo.

Iqoqa 2. Izindlela ezinqala zokuthuthukisa ikhambi lokwelapha i-HIV zisekuqondeni iziguquguquli zesidlekemagciwane se-HIV. Iqhaza lamaseli ayi-macrophage ezicutshini zesidlekemagciwane se-HIV liyinkimbinkimbi futhi alikaqondakali ngokugcwele. Kodwa-ke, amandla awo okusekela ukuphindaphindeka kwegciwane, ukuphila isikhathi eside, ukutholakala kwawo ezindaweni ezivikela amasosha omzimba, kanye nokukwazi ukungazivezi njengegciwane, konke kunomthelela ekuphikeleleni nasekuqineni kwesidlekemagciwane se-HIV ezicutshini ezihlukahlukene emzimbeni wonke. Ukuqonda kanye nokuhlasela lezi zidlekemagciwane kuyingxenye ebaluleke kakhulu kulolu cwaningo emizamweni yokuthola ikhambi lokwelapha i-HIV. Ukuthola ukuqonda ngesidlekemagciwane se-macrophage sisebenzise inhlanganisela yeqhinga elaziwa nge-flow cytometry kanye ne-immunofluorescence microscopy ukuze kutholakale futhi kuphenywe ukuphikelela kwe-HIV kuma-macrophage asezimbilaphweni. Sithole ama-macrophage avunana nokuvuvukala i-(CD68+) okucashe kuwo i-HIV-Gag p24 kanye ne-HIV-1 RNA ezindaweni la kumila khona igciwane le-HIV kubantu abane-HIV abasaqala ukwelashwa nalabo asebenesikhathi eside belashwa, okukhombisa indima angayidlala njengesidlekemagciwane se-HIV. Ngokuphambene nalokho, ama-macrophage alwa nokuvuvukala i-(CD206+) atholakala emithanjeni yezimbilapho kanye nangaphandle kwezindawo okumila kuzo igciwane. Okubalulekile ukuthi sibonisa ukuba khona kwama-macrophage CD4+TIM-4+ asemadala ezimbilaphweni. Imininingo ebikwe kulo mqingo izohamba ibanga elide ekuqhubekiseleni phambili ukuqonda kwethu izidlekemagciwane zama-macrophage e-HIV kuma-macrophage atholakala ezimbilaphweni.