- less common - milder disease - 1-2% mortality rate in unvaccinated

- more common - extensive rash, high fever - 30% mortality rate

- disease of rainforest animals - adapted to be able to spread between humans - 2022 outbreak

Exam 3 - Poxviruses Flashcards by Paige Kuhn

poxvirus characteristics

large, linear dsDNA
enveloped
complex rectangular shape
poxviridae family

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poxiruses cause ___________________

exanthematous disease - rash differs

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4 poxviruses that infect humans:

smallpox (variola)
-monkeypox
molluscum contagiosum
vaccinia

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smallpox is caused by the _______ virus

variola

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smallpox survivors are:

scarred by poxmarks and corneal blindness

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smallpox was carried by ______________ to ____________

explorers/traders; New World

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smallpox was eradicated in ________

1980 (WHO)

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mass smallpox vaccination of children is discontinued unless ________________

traveling outside of the US where smallpox is

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Variola minor virus

less common
milder disease
1-2% mortality rate in unvaccinated

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Variola major virus

more common
extensive rash, high fever
30% mortality rate

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vaccine modified variola major

mild not lethal

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flat or malignant pox variola major

very severe, 96% mortality rate

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hemorrhagic variola major

very severe, 96% mortality rate

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smallpox transmission

person to person contact, fomites

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smallpox clinical features

skin rash –> crusts –> scabs fall off
12-14 incubation period
prodromal period (2-4 days) - symptoms begin
vescicles rupture

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when is smallpox contagious

onset of rash to when all scabs come off

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monkeypox was isolated from ____________

cynomolgus monkeys

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history of monkeypox

disease of rainforest animals
adapted to be able to spread between humans
2022 outbreak

monkeypox clinical features

milder - like ordinary or vaccine modified smallpox
rash
3-17 incubation period
3-6% fatality rate

monkeypox transmission

close person to person contact

least concerning poxvirus

molluscum contagiosum (MCV)

molluscum contagiosum (MCV) clinical features

pin, pearl-like lesions
centrifugal rash
2-8 week incubation period
self-limiting (up to 5 years)

molluscum contagiosum (MCV) transmission

direct contact or formites
- rapid in daycare centers and kindergarten

vaccinia virus clinical features

localized skin infection
immunocompromised/pre-existing skin conditition - severe, systemic disease

vaccinia virus is used to vaccinate against _________ and protects against _________

smallpox; monkeypox

vaccinia virus is most similar to ______________

buffalopox

___________ is the model for all poxviruses

vaccinia virus

poxvirus virion

- M, mulberry (vesicular fluid) - C, capsule (dried scabs) - dumbbell-shaped core - lateral bodies - outer membrane

Lateral bodies

enzymes essential for viral replication

Vaccinia replication cycle

CYTOPLASM 1. Entry - cell surface GAGs - mature virion (MV) - 2 memb. (golgi & plasma memb.) - extracellular virion (EV) - 1 memb. (golgi) 2. Uncoating - core enters cytoplasm 3. DNA Replication - DNAP 4. Transcription - early genes - mRNA packaged into virion - intermediate - late genes - after genome replication 5. mRNA Turnover - D10 decapping enzyme 6. Maturation 7. Assembly - core memb., interactions with cytoskeleton 8. Release - MV (cell lysis), EV (membrane fusion, loses 1 membrane as released)

poxvirus immune evasion

- secretes viroreceptors and virokines - produce intracellular proteins to interfere with signaling

poxvirus antiviral - Tecovirimat

- treatment of smallpox - inhibits VP37 envelope wrapping protein

poxvirus antivirals - Brincidofovir and Cidofovir

- B = treatment of smallpox - C = treatment of CMV in AIDS patients - nucleoside/nucleotide analog

smallpox vaccination - variolation

puncturing of the skin with a smallpox scab from infected person to induve a localized reaction

smallpox vaccination - arm to arm passage

vesicle/postule fluid of a previously vaccinated person - not safe (spread of other diseases), banned

smallpox vaccination - US

cowpox lesions from infected calves - glycerin added to prevent contamination - emulsify and centrifuge to yield vaccine lymph

modern smallpox vaccination - Dryvax

- live, attenuated - 2 doses, bifurcated needle - cultured in skin of calves and freeze dried

modern smallox vaccination - ACAM2000

- propogate attenuated virus in cell culture - current vaccine used and in stockpile

smallpox vaccine is only given to:

vaccine lab workers, healthcare, military

Jynneos vaccine

- best current Smallpox vaccine, in stockpile - recommended for monkeypox - subcutaneous or intradermal injection (no scab formation)

smallpox eradicated

- no animal reservoirs - no long-term carrier state - highly effective, inexpensive freeze-dried vaccine - easy surveillance - centrifugal rash - containment vaccine - surveillance containment

goal of variola research

- develop antivirals - improve vaccines

why is there destruction of variola stocks

- concerns about bioterrorism and biowarfare - use of synthetic biology to build new virus