Poxviruses

Excerpt

Under modern classification, poxviruses and their family, Poxviridae, are a genomically linked lineage of large, complex, dual-stranded DNA viruses that replicate and assemble entirely in the cytoplasm, completely independent of their host’s nucleus. Historically this family is infamous for the variola virus (VARV), which was responsible for smallpox, a disease touted to hold causal mortality of more humans than all other infectious etiologies put together.

Of 28 known genera, 4 have shown to infect humans, Orthopoxviridae, Parapoxviridae, Yatapoxviridae, and Molluscipoxviridae. Only 2 are species-specific to humans. The orthopox, variola (VARV), and the only known molluscipox, Molluscum contagiosum (MCV); the latter of which is even more super-specific, permissive down to only a single human cell lineage (human basal keratinocyte).

Structurally all the Poxviridae are massive, maintaining a brick-shaped proteolipid envelope further packed with even more “mature virion” inside; each one sporting their very own fusion-ready envelope - infectious in their own right (albeit with a differing route). Here the DNA is housed in a protein core, surrounded by its assortment of transcriptional machinery, even including a viral variant of DNA-RNA polymerase.