Viral Pathogenesis II Flashcards Preview

Infection & Immunity Block > Viral Pathogenesis II > Flashcards

Flashcards in Viral Pathogenesis II Deck (14):


Have a protein coat
Some have an envelope
Can have an RNA or a DNA genome
Replicate by assembly


Localized vs Systemic

Localized spread: mucosal surface

Replication and spread:
Mucosal surface to blood
Mucosal surface to neurons


Consequences of Infection

No clinical presentation
Acute disease resulting from viral replication
Persistent/Latent infection
Immunopathological reaction
Altered development


Lytic Infection

Destroy cells

Example: rhinovirus

Perfusion of cytokines and fluid release and nose start running
Hyperchromic cells, nuclei condense, and cytoplasm doesn’t exist because respiratory epithelial layers have holes in it


Syncytium Formation

A mass of cytoplasm having many nuclei but no internal cell boundaries from cell fusing together due to enveloped viruses

Example: HIV

Surface glycoproteins on envelop attach to membrane of the host cell and causes fusion of cell membrane and envelop
Infected host cell, will make new viral glycoproteins and insert them into cytoplasmic membranes of the cells
Cells that are touching each other can then fuse via glycoproteins
Leads to giant cell as a result of fusion of many cells



Changes the cell type

Loss of contact inhibition: viral proteins interfering with cell cycle control and cells are replicating at an abnormal level

Examples: Epstein Barr Virus and Papilloma virus

Cell Cycle: G1, then synthesis of DNA (chromosome is duplicated), G2 (another growth cycle), and then mitosis
G0 is a resting phase



Can cause cancer

Example: HTLV: T cell leukemia (human T lymphotrophic virus)


Immunopathological Reaction

Scheme of immune response
Scarring of infectious eye with virus from immune reactions
Immune reactions have good and bad associations with them


Persistent/Latent Infections

Herpes simplex virus

Have a peak number of virions with the acute infection, but because a few survive, they start to replicate again causing a persistent infection that eventually escalates into a latent infection with a lower peak (compared to acute infection stage) of virion number


Altered Development

Rubella virus, cytomegalovirus
Hearing loss, blueberry muffin baby (petechiae), targets heart and eyes = Rubella


Virus Host Range, Virulence, and Number of Particles

Virus host range - humans, animals, age ranges

Viral virulence- ability to cause disease and strength of ability to infect

Number of viral particles present in inoculum: small amount vs. large amount needed; the less the more virulent

Viruses can change in their ability to cause disease


Vaccine Development

Inactivated: killed virulent virus; B cell response

Attenuated: replicating, avirulent virus; T cell response (but also B cell); provides greater protection

Subunit: proteins grown in yeast from the virus; B cell response


Interferon Production

Produced by a virally infected cell

Induces an antiviral state: synthesis of oligoadenylate synthetase and protein kinase

Virus attaches to a cell, particle enters, and then starts to replicate
Double stranded RNA: RNA viruses must go through a double stranded intermediate to replicate
Virus starts to replicate and produces double stranded RNA and causes the host cell to synthesize interferon, which is secreted into outside environment


Interferon Reactions

Interferons goes to neighboring cells that aren’t infected and bind to interferon receptors to cause the cell to go into an anti-viral state
Cascade of events produces oligoadenylate synthetase and protein kinase

Double stranded RNA will activate oligoadenylate synthetase and protein kinase in other cells, and these proteins go on to have enzymatic activity

Oligoadenylate- degrades mRNA
Protein kinase: inhibition of formation of protein synthesis initiation complex

Overall it all prevents protein synthesis so that way viral replication cannot occur