11.6 Viral Transmission and Pathogenesis Flashcards
Describe direct virus transmission. Through what can it occur?
- Occurs through direct body contact with tissues or fluids of infected individual
- Can occur through mucous membranes (e.g. eyes/mouth) and skin/wounds
Describe two mechanisms of indirect virus transmission
- Fomite transmission
- Vector mediated transmission (e.g. mosquitos)
Describe three kinds of transmissions of viruses between/within humans and other animals
- Enzootic (Within one animal species)
- Epizootic (between multiple animal species)
- Zoonotic (from animals to humans via any means)
Describe different modes of viral transmission across mucosal surfaces
- Respiratory (airborne)
- Enteric (oral)
- Sexual transmission
Describe different modes of viral transmission that involve skin penetration
- Bloodborne
- Vector-borne
- Cuts, scrapes, bites, needles
What is viraemia?
Virus existing in blood
What does it mean that viruses are obligate intracelllular parasites?
They must enter a host cell in order to replicate
What is the only situation in which the genome of a virus can serve its function?
Inside a living cell
What are four important aspects of viral pathogenesis?
- Transmission
- Viral Replication (effect on infected cells?)
- Spread within the body (areas?)
- Evasion of host defense systems
Transient vs persistent infection
Transient: successful clearance
Persistent: unsuccessful clearance
What is a single viral particle called?
Virion
List five possible effects of viral infection at the cellular level
- Cytopathic effect (cell death/cytoskeletal changes)
- Giant cell formation
- Malignant transformation
- Inclusion bodies
- No change
What is the opposite of a localised infection?
Systemic infection
What factors can influence the effectiveness of an antiviral immune response?
- Rate of virus replication & antigen presentation
- Size of dose of virus
- Route of infection/host age
- Ability of virus to evade the immune system
Which two concepts underlie the clinical presentation of viral infection?
- Effects of viral replication on host
- Symptoms caused by the antiviral immune response itself
What are the four classifications of viral infections in terms of permutations?
- Transient localised
- Transient systemic
- Persistent localised
- Persistent systemic
List five different regions in which infection can occur
- Respiratory tract
- Gastrointestinal tract
- Liver
- Nervous system
- Skin
Give an example of a viral respiratory infection
Influenza
Give an example of a viral GI infection
Gastroenteritis
Give an example of a viral Liver infection
Hep A/B/C
Give an example of a viral nervous infection
Encephalitis
Give an example of a viral skin infection
Chickenpox
Effect of tumour necrosis factor alpha
- Promotes systemic inflammation
- Inflammatory chemokines production and leukocyte recruitment
Effect of interleukin 1 beta
- Mediates inflammatory response
- Promotes inflammatory chemokine response and leukocyte recruitment
