Virology Flashcards
What is a virus? (3)
- A set of gene (instruction in DNA & RNA) packaged in a virion (protein coat).
- Obligate intracellular parasite - meaning it cannot finish its lifecycle w/o a host.
- Incapable of self-replication
Capsid
Protein shell around nucleic acid core, made of repeating structure units
Nucleocapsid
- Capsid + nucleic acid
- Protective shell around genetic material.
Envelope viruses
- Some virus types have lipid wrap around nucleocapsid.
- Warm magical blankie to keep them safe.
Virion
Hint: Villian’s sidekick
- Complete infective virus particle.
- What viruses use to infect host cells.
Viral structure:
Enveloped (5)
Hint: De-immortalized god
- Coat of lipids & proteins.
- From host during budding off.
- Easier to kill.
- Less resistant to disinfectants.
- Examples:
- Adenovirus
- Kennel cough (CaDV-2)
Viral structure:
Non-enveloped (6)
Hint: Nothing to hide behind
- Capsid coat.
- More virulent.
- More resistant to harsh environment.
- Can’t survive long in host.
- Retain infectivity after drying.
- Examples:
- Influenza
- COVID-19
T/F: Non-enveloped viral structures can mutate rapidly
True!
How do viruses multiply? (3)
- Enter: Virus enters the cell.
- Entertainment: Virus mult. in the cell.
- Exit: Virus exits the cell.
Step 1 of virus multiplying - Enter:
Virus enters a cell by two methods
- Direct cell membrane fusion - by injecting into the cell. Think of how a mosq bite works.
- Endocytosis (inward budding)
Step 2 of a virus multiplying - Entertainment:
How does it multiply?
Host cell does all the work on multiplying after the virus has entered the cell.
Use and abuse the host cell!
Step 3 of virus multiplying - Exit:
How does the virus leave/exit the cell? (2)
- Virus can kill the cell & release with the cell rupture. (This one isn’t great for the host)
- Budding from cell membrane. They literally put their coat on, then leave the cell.
What are the three responses the body can have to a virus?
- Immune system eradicates virus:
- Interferon
- Antibodies & Lymphocytes - Cell death or host death (Uh oh)
- Chronic infection:
- Viral genome becomes apart of the host cell DNA
What is interferon?
Hint: “Emergency alert system”
CHEMICAL the body makes to protect itself from viral infection
How do viruses cause death of cells?
1. D
2. E
3. A
4. T
5. H
- Damage cell membrane.
- Extinguish host cells normal mechanisms for survival (DNA, RNA, protein synthesis).
- Attract lymphocytes to kill invaded cell.
- Transform cell into cancer.
- Host killed due to dependence on invaded cells.
Your friend makes a new friend. She’s okay. All the other friends start to like her but you know there’s something off. New girl notices it and turns everyone against you. It’s too late now. You’re dead to them.
What is this?
- Viral DNA is incorporated into cellular DNA (common of retrovirus)
- Continued viral expression (no off
switch) - Transforming proteins (mimic growth
hormone) - Transforming genes (these genes activated by another ___ogen)
Cancer! An uncontrollable division of abnormal cells
Retrovirus
A virus that will attack host later on
Examples: Feline Leukemia & human HIV
How do we diagnose a virus/disease? (4)
- Direct visualization of virus.
- Serology (antiB detection).
- Virus particle (antigen) detection.
- Changes in cells/tissues
How can we prevent disease? (3)
- Isolate carrier animals.
- Immunity development.
- Decontaminate environment.
Name a few methods of catching a virus (7)
- Direct contact
- (A)symptomatic carriers
- Contaminated food/water/surfaces.
- Aerosol
- Arthropod
- Iatrogenic (DVM/hospital induced)
- Endogenous
Fomites
Object contaminated with infectious agent
Endogenous
Growing or originating from within an organism.
Like a retrovirus. They integrate their genetic code into the genome of the host.
What are some effective host immunity responses for preventing disease? (3)
- Natural immunity
- Vaccination
- Interferon
Chemical agents to kill a virus (6)
- Alcohols
- Sterilizing gases
- Halogens: Household bleach (iodine&chlorine compounds r best).
- Phenolics
- Detergents: Nolvasan & Cidex
- Oxidizing agents: Accelerated H2O2 (rescue)
Interferon
A group of signaling proteins made and released by host cells in response to the presence of several pathogens.
Physical agents to kill a virus (3)
- Autoclave: Steam heat for 15min
- Boiling
- Dry oven: dry heat for 30min
- God
Ways of killing a virus with radiation (2)
- UV light
- Ionizing
When using chemical agents, bear in mind… (6)
READ & FOLLOW LABEL!!
1. Most won’t work on organic surfaces (ex. bleach)
2. Hard water might be inactive
3. Fresh solution has to be made every few days.
4. Don’t mix products!
5. Sufficient contact time
6. Don’t apply directly to the patient
How long should a chemical agent contact time be to decontaminate for parvovirus?
At LEAST 10 minutes!
Virus diagnosis:
Serology
Detects antiB to a specific virus
Virus diagnosis:
Antigen (foreign material) detection
- Immunoassays (ELISA)
- Immunofluorescence of tissue (woods lamp?)
- Polymerase Chain Reaction (PCR)
Virus diagnosis:
Changes in cells/tissue
Cell culture
Virus diagnosis:
Direct visualization
Electron microscopy (EM)
