Mhr Topic 25: Nonenveloped Dna Viruses

Front 1

Papillomaviruses (Infection, Disease)

Back 1

1) Infect basal cells (need access to them via something like a lesion).
2) Can cause cutaneous warts, mucosal infections, and can cause cervical cancer as well as other epithelial tumors (head, neck).

Front 2

Papillomaviruses genes and proteins

Back 2

Circular double stranded genome. Has 8 early genes and 2 late genes. Actual virus only has 2 late proteins.

Front 3

What requirements must be met for Papillomaviruses to cause cancer.

Back 3

1) Expression of E6
2) Expression of E7
3) Late HPV proteins must NOT be expressed.

Front 4

E6

Back 4

E6 causes p53 degradation.
p53 is the guardian of the genome. If there is genetic damage, p53 will halt cell cycle or cause apoptosis. Usually p53 is constantly being degraded but in times of genomic stress, will be upregulated. p53 induces p21 which blocks cell cycle. E6 complexes with p53, degrading it, allowing cell to continue cell cycle despite viral infiltration.

Front 5

E7

Back 5

E7 mimics cdk which signals mitosis initiation.
Normally E2F is complexed with pRB. If cell gets a mitosis signal, cdk causes pRB to get phosphorylated which liberates E2F transcription factor. E2F stimulates S phase. E7 forms complex with pRB leading to its degradation and the release of E2F triggering S phase.

Front 6

Polyomaviridae virus genes

Back 6

Double stranded circular genome. 2 early genes 3 late genes

Front 7

Polyomaviridae (infection, Disease)

Back 7

1) Infection via respiratory route. Ubiquitous..
2) Upon immunosupression:
JCV - can cause progressive multifocal leukoencephalopothy (PML) in brain.
BKV - Can cause hemorrhagic cistitis in kidney, bladder, ureter.

Front 8

JC Virus (life cycle)

Back 8

1) Get infected via respiratory route (most people are infected, is ubiquitos).
2) Disseminates from toncils and blood and enters latent period in bone marrow and kidneys.
3) Upon immunosupression, reactivation.
4) Virus infects B lymphocytes, spreads through peripheral blood, can infect brain.

Front 9

Adenovirus Genes

Back 9

Double stranded linear genome. Contains 35 genes, approx 20 early genes.

Front 10

Adenovirus Disease

Back 10

Infections depend on disease:
1) Pediatric Respiratory disease
2) Pharyngoconjunctival Fever
3) Epidemic Keratonconjunctivitis
4) Acute respiratory disease
5) Disseminated infections in immunosuppressed (especially common in pediatric stem cell transplant patients whose immune system is totally wiped out prior to transplant).

Front 11

Pediatric respiratory disease

Back 11

Caused by Adenovirus.
Fever, pharyngitis, tonsilitis, cause 5% of common colds in children.

Front 12

Pharyngoconjunctival fever (PCF)

Back 12

Caused by Adenovirus. Infection via inadequately chlorined swimming pools or by direct nasal, oral, or conjuncctival inoculation. Usually occurs in children.
Fever, sore throat, conjunctivitis.

Front 13

Epidemic Keratonconjunctivitis (EKC)

Back 13

Caused by Adenovirus. Associated with direct inoculation and ocular trauma. Corneal epithelial cells are infected.
Causes Conjunctival/corneal inflammation (feels like something in eye), can cause chronic and permanent visual impairment.

Front 14

Acute respiratory disease

Back 14

Caused by Adenovirus. Upper and lower respiratory disease seen in military recruits. Not seen in civilian pop. Can be fatal.

Front 15

Human B19 parvovirus Genes

Back 15

Single stranded genome, 2 early, 2 late.

Front 16

Human B19 parvovirus infection

Back 16

Spreads through respiratory droplets.
Must infect cells in S phase to replicate b/c virus does not have mechanisms to push cells into S phase.
Receptors for viron entry are on hematopetic progenitor cells of erythroblasts.
Major site of replication is bone marrow.
is autonomous parovirus, does not need coinfection by another virus.

Front 17

Human B19 parvovirus disease

Back 17

Get flu-like symptoms, sometimes a rash. 10-14 days post infection, can get Fifth Disease aka Slapped Cheek Disease:
Red cheeks, rash on arms and upper legs. Women can get arthritis, and can pass virus on to fetus.

Front 18

HPV Vaccine

Back 18

2 exist. Consist of virus-like particles. Not effective against people already infected.