Patterns of viral infection Flashcards
(11 cards)
What are the various routes of infection?
Through the layers of mucosae (resp, GI) and skin
Directly through blood via needle
Through the skin via abrasion
Give some examples of viruses and their routes of infection
Influenza - respiratory
Herpes SV - contact
HIV - blood
What is an iatrogenic, nosocomial, vertical, horizontal and germline virus example.
Iatrogenic - contaminated needle
Nosocomial - in a hospital
Vertical - parent to offspring
Horizontal - all other forms
Germline - genome
What occurs after virus enters?
Local infection
Primary viraemia - in blood
Amplification
Secondary viraemia
Target organ damaged
What is tropism?
A virus’ preference to infect certain tissues
What determines tropism?
Susceptibility - needs receptors
Permissivity - ability to replicate
Accessibility - reach required tissue
What determines tropism of HIV?
Depending on which receptor it binds to
- CD4, some CCR5, using VIRAL ATTACHMENT PROTEIN - gp120
What are the outcomes of viral infection and describe them
Acute infection - rapid
INFLUENZA
Persistent infection - ongoing, low level replication
PAPILOMAVIRUS
Latent-reactivating infection - genomes maintained, no virus seen unless activated
EPSTEIN BARR
Slow infection - asymptomatic primary, reemerge upon immuno compromisation
Oncogenesis - viruses encode oncogenes to further boost replication
EBV - Burkitts lymphoma
How are infections latently reactivated?
DOwnregulate MHC
Infect tissues with less immune surveillance
Describe latency in HSV
No viral proteins detected apart from LATs , no neurons divide, but contain hundreds of copies of genome for reactivation
Viral genes can be switched on or off
What does viral infection outcome depend on?
Virus sequence - mutation in Polio strain
Virus load - Second kid has worse chickenpox as more exposure and gets more
Co-infection - bacterial inf on top of viral
Other medication
Host immume status
Host co-morbidity
Host genetics - CCR5 muation of delta 32 - HIV immunity
Host age and gender - influenza worse for women than men
