Genome sequence diversity and clues to the evolution of variola (smallpox) virus

Joseph J. Esposito, Scott A. Sammons, A. Michael Frace, John D. Osborne, Melissa Glsen-Rasmussen, Ming Zhang, Dhwani Govil, Inger K. Damon, Richard Kline, Miriam Laker, Yu Li, Geoffrey L. Smith, Hermann Meyer, James W. LeDuc, Robert M. Wohlhueter