epidemeology and pathogenesis of viral disease Flashcards
What can be used to study epidemiology
Mode of transmission
Age
Gender
Ethnic background/ country of origin
Travel history
Occupation
Season
Underlying medical conditions
What are the 6 horizontal routes of transmission
Direct contact (secretions, blood)
Respiratory
Contaminated innaimate objects
Faecal/oral
Inset vector
Zoonoses
What is vertical transmission
Mother to foetus transmission (transplacental)
What is the cycle of infection
Entry
Primary site of replication
Spread within the host
Secondary site(s) of replication
Shedding
Transmission
How can viruses enter the body
-mucous membranes or skin
Respiratory tract
Oral - GI tract
Sexual
Ocular
Percutaneous (wounds etc)
What is the course of an acute infection
Virus detected by body, immune reaction to stop and clear virus over the course of few days or weeks
What is the course of a chronic infection
The immune system is unable to clear virus infection so virus is constantly produced
What is the course of latent infections
Does not have any active pathogens at certain period but can become reactivated and cause disease (usually herpes)
What is the effect of abortive infection on cells during infection
Restriction factors block or limit viral replication
What are the effects of infection on cells
Cytopathic effect - cpe
Host cell protein translation switched off
Apoptosis (cell defence/ avoidance by virus)
Transformation
Pattern recognition receptors (PRRs)
What is transformation of a cell
Immortalisation of cell - tumours
What do pattern recognition receptors (PRRs) trigger
Innate immune response
Immune evasion
Production of interferons
What factor causes the host protein translation being shutoff
Cleavage of ‘cap binding complex’ (CBC)
What is the ‘cap binding complex’ (CBC) involved in eukaryotes
Binding the m7G cap structure at the 5’ end of all eukaryotic mRNAs during initiation of translation
How does influenza use host protein translation shutoff
The virus steals mRNA cap allowing translation of viral mRNA
What are the types of transforming viruses
Human papillomavirus (HPV)
Retroviruses
Herpesviruses
Hepatitis B and hepatitis C virus
What role do interferons play during infection
Role in inhibiting virus infection in cells
What are strategies used by viruses to block aspects of innate response
Secreted modulators
Modulators on infected cell surface
Stealth/latency
Antigenic hypervariability
Block adaptive immune response
Inhibit complement
Interfere with pattern recognition receptors (PRRs)
Block interferon and/or inflammatory cytokines
How do viruses use modulators on infected cell surface to their advantage
Mimics antagonists of immune signalling
