Details of viral cultures and nucleic acids used in the study: DNA viruses.

†PCR amplicons from RAP94 and RPO147 gene segments (421 and 485 bp respectively) were obtained from the Poxvirus Program, Centers for Disease Control and Prevention, Atlanta, GA. See text and reference [39] for further details about the VAR strains used for PCR amplification.‡Complete information about the VACV virus DNA is available at the ATCC’s Biodefense and Emerging Infections Research Resources Repository (BEI) website at http://www.beiresources.org/Catalog/tabid/248/Default.aspx.Details of viral cultures and nucleic acids used in the study: DNA viruses.