Highly magnified at 310,000X, this negative-stained transmission electron micrograph (TEM) depicted a smallpox (variola) virus particle, or a single virion. Variola
is a double-stranded DNA virus in the genus, Orthopoxvirus
. The virus enters the body via the oropharynx, or respiratory mucosa, spreads systemically, and eventually localizes in small blood vessels of the dermis, which is the layer of skin located below the more superficial epidermis.