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.

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. ISIZULU ABSTRACTS Abstract 1 Abantu abaphila ne-HIV (PLWH) abane-HIV engacindezelwe basengozini enkulu yokuthola izifo ezithathelwanayo njenge-Coronavirus ka-2019 (COVID-19). Idatha yakamuva ibonise ukuthi i-HIV engacindezelwe ihlotshaniswa nezimpawu ezinzima ze-COVID-19, kodwa izindlela ezisekela lokhu kuba sengozini azikacaci. Lapha, siqale sasebenzisa i-flow cytometry kanye nokwandiswa okuthuthukisiwe ukuhlola umthelela wokutheleleka nge-HIV kukhwalithi nokucaciswa kwe-epitope ye severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) T cell izimpendulo kumagagasi okuqala kanye negagasi lesibili. Siqaphele ukuthi abantu abangenayo i-HIV babene-CD4+ T cell impendulo enkulu kakhulu ngokumelene ne-Spike protein uma kuqhathaniswa nabantu abane-HIV abaphila ne-HIV. Ukwengeza, kube nokuncipha kokuqashelwa kwe-T cell phakathi kwamagagasi amabili, okwakubonakala kakhulu kubantu abane-HIV engacindezelwanga. Okubalulekile, sihlonze izinguquko ezine kokuhlukile kwe-Beta okuholele ekuhoxisweni kokubonwa kweseli le-T. Lokhu okutholakele kuchaza ngokwengxenye ukwanda kwe-PLWH ezifweni ezinjenge-COVID-19 futhi kugqamisa nokuba sengozini kwezinhlobonhlobo ezisafufusa ze-SARS-CoV-2 zokukhathazeka. Abstract 2 Enye yezinkinobho ezinkulu zokuthuthukisa ikhambi le-HIV ngokusebenzisa ukuqonda amandla weHIV reservoir. Iqhaza lama-macrophage ezicubu kumithombo ye-HIV iyinkimbinkimbi futhi ayikaqondwa ngokugcwele. Kodwa-ke, ikhono labo lokusekela ukuphindaphinda kwegciwane, ukuphila isikhathi eside, ukwenziwa kwasendaweni ezindaweni ezivikela amasosha omzimba, kanye namandla ngokubambezeleka kwegciwane konke kunomthelela ekuphikeleleni nasekuqineni kwemithombo ye-HIV ezicutshini ezihlukahlukene emzimbeni wonke. Ukuqonda nokukhomba lezi zindawo zokugcina amanzi kuyingxenye ebalulekile yocwaningo ekufuneni ikhambi le-HIV. Ukuthola ukuqonda nge-macrophage reservoir, sisebenzise inhlanganisela yokugeleza kwe-cytometry, iimmunofluorescence microscopy, ne-RNAscope ukukhombisa nokuphenya ukuphikelela kwe-HIV kuma-macrophages e-lymph node (LN). Sithole i-pro-inflammatory (CD68+ ) ama-macrophages aphethe i-HIV-Gag p24 ne-HIV-1 RNA ezikhungweni zamagciwane ze-HIV e-ET nabantu be-LT abaphakamisa iqhaza labo njenge-HIV reservoir. Ngokuphambene nalokho, ama-macrophages alwa nokuvuvukala (CD206+ ) ama-macrophages enziwa endaweni ngemikhumbi ye-lymphatic nangaphandle kwezikhungo zamagciwane. Ngokubalulekile, sibonisa ukuba khona kwama-CD4+ TIM4+ ama-macrophages ama-LNs. Idatha ebikwe kule thesis izohamba ibanga elide ekuqhubekiseleni phambili ukuqonda kwethu amarezebe e-HIV e-macrophage kuma-lymph node macrophages