His research involves the design of therapeutic cancer vaccines directed against human papilloma virus (HPV) and prostate cancer. Several of his therapeutic HPV vaccines have or are currently been tried out in clinical trials. He studies how HPV enters cells and also studies the interaction of HPV with the human immune system to find out how HPV escapes immune detection and how to reverse that. He has published over 280 articles that have been quoted more than 24,000 times and lead to a publication h-index of 82. He is also the inventor on 18 patents. His research is supported by NIH grants.