Disease Carriers
Viruses: Vaccinia virus
Vaccinia virus is a member of the Orthopoxvirus genus within the family Poxviridae. The agents of smallpox, monkeypox, cowpox, camelpox and ectromelia belong to this same genus. The poxvirus virion is a large brick-shaped structure housing a complex double-stranded DNA genome that encodes many genes.
Vaccinia virus is best known for its use in the world-wide smallpox eradication campaign of the 1960s and 1970s. Taking advantage of the serological cross-reactivity between smallpox and vaccinia viruses, attenuated strains of vaccinia virus were used successfully to eradicate the scourge of smallpox. Despite the success of the vaccination campaign, use of vaccinia virus can cause occasional adverse reactivities, ranging from swelling and redness at the site of inoculation, to death in a very low percentage of individuals. Experts have proposed the use of highly attenuated strains of vaccinia virus as possible recombinant vaccine vectors expressing antigens from other disease agents. While these recombinant viruses have not been licensed for use in humans, they have been very useful as laboratory tools.
A transmission electron micrograph of vaccinia virus, negatively stained to enhance contrast.
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