CONTRIBRUTION OF BK VIRUS miniT PROTEIN TO VIRAL ONCOGENIC ACTIVITY

Open Access
Author:
Barrantes Gomez, Diana Paola
Area of Honors:
Biochemistry and Molecular Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Richard John Frisque, Thesis Supervisor
  • David Scott Gilmour, Honors Advisor
  • Scott Brian Selleck, Faculty Reader
Keywords:
  • viral transformation
  • oncogenic virus
  • polyomavirus
  • BK Virus
  • miniT protein
Abstract:
BK virus (BKV) is one of five pathogenic human viruses in the Polyomaviridae family. This polyomavirus infects more than 80% of the human population. Most clinical studies suggest that in immunocompetent hosts, the virus persists in many organs following a primary infection, although the asymptomatic infection mainly involves the kidneys and peripheral blood leukocytes. On the other hand, in a patient with an underlying immunocompromising condition, often involving T cell deficiency, reactivation of the viral infection may occur, leading to serious complications such as hemorrhagic cystitis in bone marrow recipients, and BKV nephropathy, a major cause of graft dysfunction and rejection in renal transplant recipients. Experimental in vitro and in vivo models have also shown BKV to be an oncogenic agent; BKV induces tumors in rodents, and is associated with several human cancers. BKV, a double stranded DNA virus, produces three early proteins: large, small, and mini TAg (TAg, tAg, miniT). These three proteins are produced by alternative splicing of a common precursor mRNA. In this study I have demonstrated that miniT contributes to BKV transformating ability. I completed the sequence of the BKV(WT9) genome, and created a miniT null mutant (BKV(WT9)-Δ4366) by introducing a point mutation at the donor splice site for the miniT transcript. This point mutation disrupted the consensus donor sequence for miniT mRNA without altering the coding sequence of TAg. I used a dense focus assay to compare the ability of the wild type and mutant forms of the virus to induce transformation of the rodent cell line, Rat 2. My experiments suggest that miniT protein does indeed contribute to viral transforming efficiency. Isolated cells transformed by wild type vs. mutant viruses produced the expected early viral proteins.