Chapter 13: Viruses and Prions

Viron

a virus particle

Naked virus

capsid and nucleic acid

Enveloped virus

capsid, nucleic acid, and lipid bilayer

capsid

Outer protein coat of a virus

neucleocapsid

nucleic acid + capsid

helical

isometric

Complex virus

False (enveloped and naked viruses can have spikes)

True or Flase

Only enveloped viruses can have spikes

Matrix proteins

fill the region between capsid and envelope

Nucleic acid of virus

-can have DNA OR RNA (not both)

-single or double stranded

-circular or linear DNA

-linear RNA

10nm

viruses can be as small as ___

and as large as 500nm

Virus replication

Host/tissue specific

Due to host receptors for the virus

True

True or False

Viruses cannot replicate outside of host

Nucleic acids

Viruses uses host proteins, enzymes, ribosomes, and ____

feline leukemia

viral disease that impairs the cat's immune system and can cause cancer

Virus-Host Interactions

Disease or genetic alteration

Productive infection

viral infection in which more viral particles are produced

-Host will either lyse and die

-Or will replicate and produce more viruses

Latent state

Virus integrates into plasmid or genome

No symptoms or clinical signs evident

-Host cell will multiply and phenotype will change

Bacteriophage Lytic replication

1. Attachment: Phage binds to bacterial cell

2. Penetration: Phage injects DNA into the cell

3. Replication (synthesis): Phage commandeers host cell factors to transcribe and translate viral genes

4. Assembly (maturation): formation of active phage

5. Release: Bacterial cell lyses and new phages are released

Bacteriophage

Can be used as a possible treatment to bacterial infections

Lysogeny

1. Attachement: attaches to host

2. Injection: injects linear DNA

3. Integration: Prophage integrates in DNA chromosome

4. Division: cell divides

5. Excision: of phage DNA

6. Replication: of phage

7. Release: Host cell lyses

Temperate bacteriophage

bacteriophages which can choose between a lytic and lysogenic pathway of development

lysogenic conversion

when a bacterium acquires a new trait from its temperate phage (typically toxins)

Streptococcus pyrogens

Produces Scarlet fever

Clostridium botulinum

Produced Botulism

Corynebacterium diphtheria

Produces diphtheria

Transduction

Transfer of bacterial gene info using bacteriophage

Generalized transduction

random bacterial DNA is packaged inside a phage and transferred to a recipient cell

Specialized transduction

a highly specific part of the host genome is regularly incorporated into the virus (only during lysogenic infections)

transducing particle

bacteriophage progeny that contains part of a bacterial genome instead of phage DNA due to an error during packaging

Hybrid DNA molecule

Virus and bacteria DNA

Animal viruses

characterizes by genome structure, virus particle structure, presence of envelope

- viridae

family names

(based on genome, structure, and envelope)

- virus

Genus

Species

derived from disease cause

Animal Virus Replication

1. Attachment

2. Penetration

3. Uncoating

4. Biosynthesis/Genome Replication

5. Assembly (maturation)

6. Release

7. Shedding

Shedding

Leaving host (typically the same as entry)

Transmission

Entry into a new host

Release

Leaving a cell (typically by budding, exocytosis, and lysis)

Fusion

Virus fuses to cell membrane for penetration

Endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane

Acute infections

-short (days-months)

-Infected cells may die (may or may not lyse)

-Virus shed during infection

Immunity

Host will develop this when they beat the virus

Persistent infection

an infection that stays in the system for a long time and you may or may not have symptoms

Chronic infection

Virus continually produced

latent infection

infection in which the infectious agent is present but not causing symptoms

prodomal stage

vague feelings of discomfort; nonspecific complaints

Disease stage

Symptoms manifest and spread is possible.

Covalescent stage

recovery phase

tumor

A mass of abnormal cells that develops when cancerous cells divide and grow uncontrollably.

Benign tumor

A tumor that remains at its original site in the body.

malignant tumor

a tumor that spreads throughout body