All is Fair in Love and Warts
He proclaimed she had given him warts
Of the most ignominious sorts
Said that her papilloma
Had entered his soma
And the issue was clearer than quartz
She denies having given him warts
Says that "His allegation distorts.
It's incredibly plain
That they differ by strain
As shown in my doctor's reports."
And despite his assertion of torts
On the issue of giving him warts,
She was quickly acquitted
Of having transmitted
(And upheld in the lowest of courts).
Robert D. Siegel
November 16, 1993
The Papovaviridae family is comprised of two genera: papillomaviruses and
polyomaviruses. The family name is derived from the names of three
prototypical members: rabbit papilloma virus, mouse
polyoma virus, and
simian virus 40 (SV40), originally called vacuolating virus.
has several general features in common:
Genome: It consists of single molecules of supercoiled,
(covalently closed), double-stranded DNA that are replicated in the
nucleus and bound to histones H2a, H2b, H3, and H4. Genome lengths vary
slightly by genus; polyoma viruses are 5 kilobases, while papilloma
viruses are 8 kilobases. The virions are spherical in shape and have
non-enveloped, icosahedral capsids with a triangulation number, T=7. The
genome does not encode a viral polymerase; instead, it uses the host's
polymerase during replication. The virally encoded T antigen acts to
direct the host DNA polymerase to the viral genome. Interestingly, while
the reading frames of papillomaviruses are encoded on a single strand of
DNA, for polyomaviruses both DNA strands encode functional proteins. (see
Most of the species have a narrow host range.
Replication and assembly occur in the nucleus.
Virions are released via cell destruction.
Some infections are characterized by oncogenesis or host cell
Transmission usually occurs through direct contact, including sexual
The family is resistant to inactivation by heat or formalin.
The viruses encode 5-7 structural proteins and 3 capsid proteins
Human papillomaviruses (HPV 1-62)
Shope papilloma virus of rabbits
Polyoma virus of mice
Simian virus 40 (SV40)
JC and BK viruses
These two genera differ in several aspects:
1) capsid size (Polyoma = 40 nm, Papilloma = 55 nm)
2) length of genome (Polyoma = 5 kb, Papilloma = 8 kb)
3) genomic organization
Warts (papilloma), including condyloma acuminata (genital warts)
Progressive Multifocal Leukoencephalopathy (PML)
Cervical carcinoma (HPV 16, 18, 31, 33)
Squamous cell carcinoma
Richard Edwin Shope -discovery of a virally transmitted cancer of
William Fliers (and coworkers) -DNA sequencing of SV40, the first
eukaryotic entity, 1977.
Paul Berg (Stanford Medical School Professor) -development of SV40
eukaryotic cloning vector; Nobel Prize, 1980.