Investigating the Functional Consequences of Novel EPHA2 Polymorphisms on KSHV Infectivity and KS Development Among South African HIV/AIDS Patients
Dr Georgia Schäfer
Title of the project
Investigating the functional consequences of novel EPHA2 polymorphisms on KSHV infectivity and KS development among South African HIV/AIDS patients.
Kaposi’s Sarcoma (KS) is the most common Acquired Immune Deficiency Syndrome (AIDS)-related malignancy globally and is of particular significance in sub-Saharan Africa where, due to the Human Immunodeficiency Virus (HIV) epidemic, KS is the cause of significant morbidity and mortality. The oncogenic Kaposi’s Sarcoma-associated herpes virus (KSHV) is the etiological agent of KS. Although KSHV seroprevalence in sub-Saharan Africa is high, not all AIDS patients develop KS, suggesting that host genetic factors contribute to susceptibility. The infection mechanism of KSHV in endothelial cells has recently been elucidated and highlights Eph Receptor A2 (EphA2) as a specific host receptor for virus entry. Furthermore, EphA2 has been implicated in oncogenesis and is upregulated in a number of cancers including KS. We therefore hypothesised that mutations in the KSHV host receptor’s coding region could result in an altered EphA2 that could affect susceptibility to KSHV infection and/or KS development among HIV/AIDS patients.
In a previous CANSA-funded study we tested this hypothesis by analysing the coding region of EPHA2 in a cohort of 150 South African HIV/AIDS patients which were grouped into three groups of 50 patients each, namely patients with KS as well as patients without KS who were KSHV positive or KSHV negative, respectively. A number of variants were identified throughout the ephA2 coding region and assessed statistically for association with KSHV susceptibility and/or KS prevalence. Of those, several variants were predicted to result in changes on the protein level that could cause functional alteration of the EphA2 receptor and thereby affect KSHV uptake and infection or KS development. The herein proposed project will build on these data, and we will now test the identified variants in terms of functional involvement for KSHV infection or KS development. We will clone and overexpress them in endothelial cells (which have been silenced for endogenous EphA2 by CRISP/Cas9 knockdown) and determine their impact on KSHV infection. For this purpose we will establish a KSHV infection system in our laboratory in collaboration with Prof. Thomas Schulz (Medical School Hannover, Germany), as no experimental KSHV infection model is available in South Africa yet. Furthermore, the impact of the identified EphA2 variants on KS development will be assessed by qRT-PCR to markers associated with KSHV-mediated tumorigenesis.
Research on KS/KSHV is still extremely underrepresented despite the high burden of disease in Southern Africa. The dentification and functional validation of variants in the KSHV entry receptor, EphA2, will contribute significantly to our understanding of the epidemiology of the KS burden in the South African population additionally burdened by the high HIV/AIDS prevalence. It will open new doors for the development of risk evaluation of KS by using state-of-theart molecular techniques that will be novel in the South African research landscape.