A 35-year-old professional businesswoman notices the appearance of several hyperkeratotic, well-demarcated growths on the palm side of her index finger and on her toe. They do not change in size and cause her only minimal discomfort. Biopsy of one of the lesions is shown at 40x. Which of the following viruses is the most likely etiologic agent?H&E strain (40x) of skin biopsy