MCB55 - Poxviruses

large genomes

Proxviruses have

immune evasion

Poxviruses are experts in

obligate intracellular parasites

Viruses are

genomes

Viruses have different types of

mRNA

All virus genome types make

host messages

Viral mRNA are just like

proteins

mRNAs encode for

+ sense

the genome can be translated into proteins

- sense

other strand must be transcribed to make viral proteins

Double-stranded DNA genome

Poxviruses have a

vaccine

Pox viruses have the first

eradicated

Poxvirus was the first disease to be

humans and other mammals

Host species for Poxviruses include

Variola virus

What is the etiological agent of smallpox?

overlapping and do not have introns

Poxvirus genes are not

cell cytoplasm (no splicing)

poxviruses replicate in the

immunomodulatory genes

Poxviruses encode many

100 open reading frames

Poxviruses have over

open reading frames

Genes that encode Proteins

Immunomodulation

Poxviruses are experts in

Poxviruses make a decoy receptor for
Interferons (IFN) which Blocks signaling that turns on an
antiviral gene program

Example of poxvirus immunomodulation

interferons (IFNs)

infected cells that sense viral infection release a set of molecules that are called

many proteins inside the cell whose function is to combat viral infection

Nearby uninfected cells that have the IFN receptor will make

ancient disease of humans

Smallpox is an

respiratory droplets (prolonged contact for person-to-person spread), ‘fomites’, close contact

smallpox transmission

~30% (90% in babies)

smallpox lethality

scarring

smallpox leaves lots of

3,000 years ago in India, China, and Africa

Earliest evidence of smallpox from more than

1000 CE

Endemic in Asia by

19th century

Endemic in every European country at the end of the

1200-1600 CE

Large epidemics in Europe

1507-1524 CE

Large epidemics in the Americas

Mummies with smallpox scars, Nigeria has essentially a god of smallpox

historical evidence for smallpox

40% of this city of 200,000 died from Smallpox in 1520 Smallpox infections: a gruesome role in history

Tenochitlan

noculation/variolation with dried pox, Risk of Death: 14% → 2%, 2-3% of people develop severe smallpox infection, spread disease and become infected with other pathogens

16th century Chinese vaccine

1790s England, Milkmaids were protected from smallpox due to constant exposure to Cows who have related virus called cowpox, Inoculated gardener’s son with cowpox and after a while put smallpox scabs in him and he did not get infected

First “scientific” vaccine

Variolation

Dried material from infected persons ground up and placed under skin or inhaled, thus protecting the newly-infected individual

vaccinia virus, Live-attenuated, Adapted in chicken cells

Current Smallpox vaccine

Variola

What causes smallpox?

monkeypox

vaccinia virus-MVA is more closely-related to

protective immunity against another poxvirus (the amount of protection depends somewhat on the degree of replication)

Despite their genetic diversity, infection with one orthopoxvirus can confer

many times

Poxviruses have jumped over to people

We eradicated it in 1979, Vaccine is key, We have stopped vaccinating people for smallpox because there is no more need

Smallpox is dead

1980

We stopped vaccinating people against smallpox in

over 70%

What percentage of the global population is no longer immune to smallpox?

fevers, aches and painful fluid-filled skin lesions, can be fatal

mpox symptoms

rodent reservoir/spillover

mpox is likely a

gay community

mpox spread predominantly in the

Africa

majority of mpox cases are in

infecting people across epidemics

Different versions of MPXV are

travel related

in the US many mpox infections are

Not all infections are detected, Less severe cases not documented, Other health conditions

CFR: Case Fatality Rate can affected by

DRC/African Region

Where is the current mpox outbreak?

mpox infection

Smallpox vaccination protects against

Less measurement of infection means case rates aren't entirely accurate, Has been difficult to get vaccines to affected areas

Mpox spread globally: 2022-now

symptoms

sterilizing vaccination protects against infection and

• Fewer, less
  disseminated & faster
  healing lesion

• Less fever & systemic
  symptoms

• Lower hospitalization

after sterilization vaccination

initial smallpox vaccine

a sterilizing vaccine is taken after the