Lecture 1 - Pox and Papilloma virus

What are the two subfamilies of poxviridae family? What species do they infect?

-Chordopoxvirinae: vertebrates

-Entomopoxvirinae: invertebrates

How many genera is Chordopoxvirinae divided into? What is it based on?

-10 genera

-Based on species infected, morphology, and genomic structure

What is the make-up of a poxvirus?

-Double-stranded DNA

-Large

Where do poxviruses replicate?

Cytoplasm (unlike most DNA viruses)

What are the three classes of gene expression for poxviruses?

1. Early - Before DNA replication, focuses on immune evasion and DNA replication machinery

2. Intermediate - Depends on early proteins; initiates DNA replication and activates late genes

3. Late - Depends on DNA replication, focuses on structural proteins and assembly

What are the four infectious forms of vaccina virions?

1. Intracellular mature virus (IMV)

2. Intracellular enveloped virus (IEV)

3. Cell-associated enveloped virus (CEV)

4. Extracellular enveloped virus (EEV)

What are the target cells for localized infection of poxvirus?

Keratinocytes

What occurs with a systemic poxvirus infection?

-Cell-associated viremia preceding skin lesions

-Infected monocytes spread virus to distal sites

-Significant mortality

What is the reservoir for cow pox? What species is it most severe in?

-Reservoir = rodents

-Most severe in cats

What is the reservoir for monkeypox? How is it transmitted?

-Reservoir = African squirrel

-Transmitted through bites, direct contact, and aerosol

What are the common symptoms of monkeypox in animals?

Fever, rash, pustules, conjunctivitis

What is the control for Monkeypox?

-Smallpox vaccine (85% protective)

-Quarantine for 6 weeks

-Clean with bleach and EPA disinfectants

Where are parapoxviruses found? How are they transmitted?

-Found worldwide

-Transmitted through direct contacts or fomites

Where is swinepox virus found (genus suipoxvirus)? How is it transmitted?

-Found worldwide

-Transmitted through pig louse bite

What diseases are included in the Genus Capripoxvirus? Where is it found?

-Sheeppox, goatpox, and lumpy skin disease (cattle)

-Found worldwide outside of US

How can capripoxviruses be prevented and controlled?

-Cross protection

-Vaccination

-Exclusion in capripoxvirus free countries

What species does myxoma virus affect? What disease does it cause? How is it transmitted?

-Rabbits

-Causes myxomatosis

-Transmitted by biting arthropods and respiratory droplets

What are the two clinical forms of fowlpox?

1. Cutaneous

2. Diphtheritic (wet)

What clinical signs does the cutaneous form of fowlpox present as? How is it transmitted?

-Small papules on comb, wattles and around beak

-Transmission through biting arthropods or skin abrasions

What clinical signs does the diphtheritic form of fowlpox present as? How is it transmitted?

-Systemic infection of mucous membranes and asphyxiation

-Transmitted by air droplets

What are squamous papillomas?

Papilloma viruses that only infect keratinocytes

What are fibropapillomas?

Papilloma viruses that infect keratinocytes and underlying fibroblasts

What are the clinical signs of papilloma virus?

-Usually subclinical

-Self-resolving, cutaneous, or anogenital warts

What are the oncoproteins for papillomavirus 16 (HPV16)?

E6 and E7

How does the E7 protein lead to tumor formation?

-Binds to retinoblastoma protein (Rb) and degrades it

-Cell division proceeds and promotes cancer

What does pRb (retinoblastoma protein) do?

Blocks cell division

What does p53 do?

-Tumor suppressor gene

-Promotes apoptosis and inhibits cell proliferation

How does the E6 protein lead to tumor formation?

-Binds to p53 and degrades it

-Inhibits apoptosis and allows cancer cells to proliferate

What is a non-infectious virus like particle (VLP)?

-Safe and immunogenic

-Used for vaccines for HPV-16 and -18