9/22

Question 1

Viral envelope

Answer 1

Not necessary, all animal helical viruses have one

Made of lipids, proteins, and glycoproteins

Comes from host memebranes

Disrupted by drying agents, acid, detergents, and solvents

Almost always transmitted by fluids like blood or respiratory droplets

Question 2

Positive vs Negative Sense ssRNA

Answer 2

Positive: like mRNA, ready to be translated into protein

Negative: copied into complementary strand before used for protein translation

Question 3

Viral Replication

Answer 3

1. Attachment
2. Penetration
3. Uncoating
4. Synthesis, translation, genome replication
5. Assembly
6. Release- budding vs. lysis

Question 4

Penetration and Uncoating

Answer 4

Plasma Membrane: RSV and HIV, fuse with plasma membrane and then uncontrolled into cytoplasm

Endosomes: flu, get inside endosome, low pH causes viral envelope to fuse with cell membrane and expel uncontested genome into cytoplasm

Nuclear Membrane: adenovirus, form endosome, no envelope so cause endosome to lyse and deliver genome to cytoplasm, can uncoat at nuclear membrane

Polio virus has no envelope but hydrophobic capsid, genome can pass into cytoplasm after come into contact with plasma membrane or endosome

Question 5

Viral Synthesis/Translation

Answer 5

Positive sense RNA can immediately begin translation, make polyprotein, cleaves into capsid proteins and non-structural proteins like RNA-dependent RNA pol

Negative sense needs RNA-dependent RNA pol, DNA virus goes to nucleus, reverse transcriptase virus needs RNA-dependent DNA pol

Question 6

Epstein Barr Virus

Answer 6

Can be a lytic infection of B lymphocytes or undergo a latent stage

Transformation of B lymphocytes, cell immortalization and transforming effect leading to monoclonal cell growth, causes lymphoma

Question 7

Different Types of Viral Acuity/Latency

Answer 7

Acute infection: common cold, single disease outbreak

Acute infection with rare late infections: measles and then Subacute sclerosing panencephalitis years later

Latent infection: varicella-zoster, chickenpox then shingles after long period of no symptoms

Chronic infection: Hep B, symptoms from infection resolve but virus persists and sheds, cirrhosis of liver

Chronic infection, late disease: HIV, neurological problems later