Prevention of HPV16 Infection via Small Molecule Inhibition of A2t
Authors:Andrew Jimenez, Andrew Woodham
Mentor:W. Martin Kast, Professor Molecular Microbiology and Immunology, USC
Human papillomavirus (HPV) is the most prevalent sexually transmitted virus, with approximately 75% of the sexually active population in the US acquiring an infection during their lifetime. Infection by HPV leads to cervical cancer, which results in approximately 250,000 deaths annually worldwide and leads to 25% of all neck and throat cancers. Fifty percent of all cervical cancers are caused by HPV16, the most oncogenic genotype of HPV. The Kast lab has recently identified that the annexin A2 heterotetramer (A2t) is an HPV16 entry receptor on epithelial cells. Small molecule inhibitors that disrupt A2t tetramer formation have been identified, but their ability to inhibit HPV16 uptake and infection is unknown. Here we hypothesize that A2t inhibitors (A2ti) will prevent HPV16 infection of epithelial cells. Epithelial cells were treated with increasing concentrations of A2ti prior to the addition of HPV16 Pseudoviruses and then viability of the cells was determined. Additionally, cells were treated with increasing concentrations of A2ti prior to the addition of HPV16 particles labeled with a pH sensitive fluorescent dye to determine the effect of A2t inhibition on HPV16 endocytosis at different time points measured with flow cytometry. Co-immunoprecipitation assays revealed that A2ti effectively disrupted A2t formation on the cell surface. There was a significant decrease in HPV16 infection of epithelial cells treated with A2ti, which was 100% effective at preventing infection compared to control treated cells. Furthermore, A2ti treated epithelial cells showed a clear decrease in HPV16 endocytosis suggesting that the inhibition of HPV16 infection with A2ti can be attributed in part to a block in HPV16 internalization. Small molecule inhibition of A2t completely prevents HPV16 at non-toxic concentrations. These findings are the first to show that targeted inhibition of the HPV16 receptor A2t can block infection.