Development and utilization of novel HIV-1 infectable mouse models to evaluate HIV-1 treatment, prevention, and pathogenesis

Abstract

Development and utilization of novel HIV-1 infectable mouse models to evaluate HIV-1 treatment, prevention, and pathogenesis Almost 78 million people have been infected with human immunodeficiency virus (HIV) since the first reported case in 1981. In spite of significant progress in treatment and prevention worldwide, in 2013 the World Health Organization estimated that about 35 million people were living with AIDS, 1.5 million people died from HIV-1 related causes and about 2.3 million people were newly infected with HIV-1 (1). The limited availability of small animal models to investigate HIV-1 prevention and treatment has greatly hampered preclinical testing of new microbiocides and therapeutics. Mice are not able to be infected with HIV-1 due to several replication blocks in mouse cells including structural differences in mouse homologues of human proteins that are required for HIV entry, such as CD4 and CCR5, and Tat function, such as the transcription factor Cyclin T1, which mediates elongation of the HIV genome. To circumvent these blocks, we constructed hu-CD4/CCR5/CyclinT 1 (hu-CD4/R5/cT 1) transgenic mice to express the human homologues of CD4, CCR5, and CyclinT 1. To provide increased sensitivity in the detection of HIV-1 we used a replication-competent HIV-1 reporter virus that stably expresses the Renilla reniformis luciferase gene (HIV-LucR) or NanoLuc luciferase (HIV-nLuc).;In Chapter 2 of this thesis I will be discussing the development of the hu- CD4/R5/cTI mouse model and the utilization of this model to test potential HIV-1 therapeutics to inhibit HIV-1 infection. Specifically I will speak about the use of the highly sensitive HIV-LucR virus which enabled us to quantify the level of HIV-1 infection after intravenous, intrasplenic, or intravaginal inoculation. In addition, the HIVLucR virus was found to be capable of infecting the appropriate HIV-1 target cells, CD4+ T lymphocytes and macrophages, in the hu-CD4/R5/cT1 mouse model. We will demonstrate that this model can be used to test HIV-1 therapeutics by reporting inhibition of HIV-1 infection using combination antiviral therapy or the infusion of broadly neutralizing antibody, VRCO1.;In Chapter 3 I will demonstrate that hu-CD4/R5/cT 1 mice can be used to evaluate vaginal microbicides to prevent the acquisition of HIV-1 infection after intravaginal challenge. Specifically, we decided to investigate the comparative efficacy of 1% tenofovir (TFV) vaginal gel to the use of the more potent anti-viral drug tenofovir disproxil fumarate (TDF) formulated as a vaginal gel. TDF is 100 times more potent than tenofovir at inhibiting both HIV-1 and HSV-2 infection due to its rapid cellular uptake and increased intracellular concentration (2). Using the hu-CD4/R5/cT 1 mouse model we will demonstrate that vaginal application of 0.3% TDF gel was more effective in protecting against the acquisition of HIV-1 infection in hu-CD4/R5/cT1 than 1% TFV. We will also demonstrate that co-infection with HSV-2 increased the level of HIV-1 infection in lower genital tract and induced dissemination of HIV-1 into the draining lymph nodes of hu-CD4/R5/cT 1 mice.;In Chapter 4 I will evaluate the efficacy of an IL-15R-superagonist to boost the cytotoxic activity of Natural Killer (NK) cells to kill HIV-1 infected cells. Using a novel humanized mouse model constructed by intrasplenically injecting NOD-SCID-IL2rgamma-/- mice with human peripheral blood mononuclear cells, we will demonstrate the in vivo treatment with the IL-15R-superagonist potently activated NK cells to markedly inhibit HIV-1 infection.