Viruses - Intro Flashcards
How are Virus families classified?
Virion Structure
Prescence/abscence of an envelope
Host Range
Mode of Replication
What is a Virion?
The entire virus particle.
The outer protein capsid & inner nucleic acid.
What part of the virus replication process occurs in the nucleus of host cell?
mRNA synthesis
Where is the genomic nucleic acid synthesised?
the cytosol
Why must viruses be cultured in live cells?
Because viruses can only reproduce within a host cell
How are cells grown for virus cultures?
In a nutrient containing medium in a 5% CO2 atmosphere.
How are HIV & HEP B transmitted?
Blood-Borne
Sexual
Vertical
How is Polio transmitted?
Faecal-oral transmission.
What is droplet transmission + an example.?
Transmission by large particels like sneeze or cough particles, has a very short range.
Influenza & RSV
How is the herpes simplex virus transmitteD?
By close-contact
What is zoonotic transmission?
direct transmission from animals to humans via air (influenza) or bites (rabies)
What are examples of airborne virus’?
Measles & chickenpox
What is vector-borne transmission?
virus’ transmitted by anthropods like mosquitoes & ticks.
What does host range mean?
The range of hosts a virus can infect.
E.g. smallpox & measles only infect humans
How can a novel virus be transmitted to humans?
Coinfection of human & animal/bird strains in one organism can lead to recombination & generation of a new strain trasmittable to both.
What is viral latency & examples
Expression of the viral genome is restricted within the hostcell until reactivated.
E.g. Herpes Simplex
What is transformation of a viral infection?
Long term infection with altered cellular gene expression.
e.g. Epstein-Barr
What common virus’ result in chronic infection?
HIV, HEP B & HEP C
Example of a virus cleared with no lasting immunity?
Hepatitis C
Example of a virus cleared with long term immunity?
Measles
What 3 things can be dected to diagnose a virus?
Full organism
PArts e.g. antigen or nucleic acid
The immune response toa apthogen e.g. antibodies
How is a whole virus oranism detected?
By microscopy & culture, neither of which are used anymore
How is part of an organism detected?
Antigen or DNA/RNA detection
reacts with a coatin, e.g. antibody coating reacts with antigen
What is immune resposne detection used to determine?
Acute infection and prior infection.
What two reasons are there for the low use of anti-virals?
There are often side effects (toxicity to host cell)
There are limited viral protiens to target because they use host cell enzymes.
What 4 things are antivirals used for?
- Prophylaxis (prevents infection)
- Pre-emptive Therapy (when infection detected but no symptoms)
- Overt disease treatment
- Suppressive Therapy (Keeps viral replication below tissue damae rates)
In what 3 ways do viruses cause cancer?
- Drives cell proliferation
- Prevents programmed cell death
- persistent inflammatory process leads to cancer via reactive oxygen species
Examples of respiratory viral infection:
Influenza A
Rhinovirus
Respiratory Syncytial Virus
Examples of Gastrointestinal viral infection?
Rotavirus
Examples of neurological viral infections?
Enterovirus
Herpes Simplex Virus
Examples of viruses causing tumours?
Papillomavirus
Retroviruses
