POX

Question 1

What 3 genera make up the Family Poxiviridae?
• identify key species with the genus.

Answer 1

3 Genera in the family
• Genus orthopox – variola (small pox), vaccinia (lab strain used to eradicate SPox), cowpox, Monkeypox

• Genus Parapox
• Unclassified – molluscum contagiosium

Question 2

What stucture is characteristic of poxviridae viruses?

Answer 2

Poxviridae

Structure
Large COMPLEX structure that is ENVELOPED with dsDNA genome

Replication Cycle
Cytoplasmic replication made possible by carrying a RNA (DNA dep. RNA pols) and DNA polymerase
***HIGHLY unusual that a DNA virus can replicate in the cytoplasm***

Question 3

How is smallpox typically spread?

Answer 3

Transmission
Most commonly RESPIRATORY spread (when lesions are in the mouth). Scabs also carry transmissible virus.

Question 4

What does Pox virus do after entering the body?
• what causes death by this virus?

Answer 4

Pathogenic Mechanism
1. Enters the upper respiratory Tract (prodromal period of ~12 days)

2. Migrates to Lymphatics (macrophage)

3a. Secondary Viremia occurs most often with Hemorrhage of small vessels of the dermis leading to Rash +Pox
3b. Primary viremia may spread to Spleen, Liver, Bone marrow

4. Death due to toxic effects on vascular endothelium

Question 5

What were the keys to erradicating the Small Pox?

Answer 5

Keys to Erradication:
• Effective Vaccine
• Humans are the only Reservoir
• No healthy carriers or subclinical infections
• Vaccine

Question 6

What kind of vaccine is the small pox vaccine?
• who should NOT get this?

Answer 6

Treatment
Prophylaxis: LIVE VACCINE (good for 3 yrs, gone after 20)
Cannot give vaccine to:
• Pregnant or Breastfeeding women
• Immunodeficient people
• Eczema or Atopic dermatitis
• anyone under 18 (unless its an emergency)
• people with prior heart disease (myocarditis possible).

Question 7

What adverse reactions are most associated with the Smallpox vaccine?

Answer 7

Adverse Rxs: Severe rxn > Life-threatening rxns > encephalitis or shock

Question 8

What are the 2 forms of Small Pox and how do they differ?

Answer 8

Mortality
25% for Variola Major
1% for Variola Minor

Question 9

Who gets Molluscum Contagiousum?
• how do they get it?

Answer 9

Molluscum Contagiosum (POXVIRUS)

Transmission
Childhood form: Skin to Skin
Adult form: Sexually transmitted

Question 10

How does Mollucsum Contagiosum present?
• Prognosis?

Answer 10

Disease Presentation
Childhood form: Lesions on the face, trunk, and limbs
Adult form: Lower abdomen lesions
**In both forms the lesions disappear in 2-12 mo.

Question 11

How do you diagnose someone with Molluscum Contagiosum?

Answer 11

Dx: Clinical + Cytoplasmic inclusions in the keritinocytes of the affected area

**Note these inclusions are important because Pox is the ONLY dsDNA virus that can replicate completely in the cytoplasm**