Vaccine + Viruses Flashcards
how do active + passive immunisation differ
active = body creates its own immune response as if infection had actually occurred (so memory cells form)
given before exposure
passive = vaccine contains pre-formed antibodies (prefabricated immune response content Ab concentrate)
given after exposure
what is PEP
post-exposure prophylaxis (like for HIV)
medication to prevent infection after exposure occurred so pt doesn’t develop infection
when are live-attenuated vaccines given
if young, healthy pt as it won’t cause disease
not for immunocompromised or old, as immune system too weak
so pt can develop disease the vaccine aimed to treat
how do DNA/RNA + mRNA vaccines differ
DNA/RNA - codes part of gene that forms pathogenic proteins in host cell
mRNA - inherently unstable so needs to be packaged
what are the different vaccine types
live-attenuated
dead/inactivated
recombinant: subunit (proteins), polysaccharide/conjugate (polysaccharides + protein), toxoid (harmless version of toxin), DNA/RNA (virus coded so can be made in pt)
what is herd immunity
when infection can’t be transmitted as too many individuals in population are already immune
herd immunity depends on R0 (how many others get infected by 1 case)
so if RO<1, infection can’t spread
what is original antigenic sin
impact of first encounter with antigen on lifelong immunity
virus has slightly changed
so different primary response ineffective for 2nd antigen exposure
as Ab can’t neutralise the slightly changed virus
how do primary + secondary antigen exposure differ
primary - causes immune response of B (make antibodies) + T (cellular defence)
secondary - causes rapid response
how do adjuncts work
sth added to vaccine (eg polysaccharide)
to create a stronger immune response
so less vaccine needed to produce appropriate immune response
what are different adjuncts
aluminium hydroxide - used in many vaccines
CpG, flagellin (TLR agonist)
CpG used in HepB vaccine
AS03, MF59 (microfluorised agents, emulsion)
AS03 used in pnadremix swine flu vaccine
what are the principles of viral pathogenesis
viruses have specific tropism to target cells (like CD4T for HIV)
so binds to specific receptors (like CCR5/CXCR4 for HIV, CD54 for rhinovirus)
need to evade immune system
viruses inhibit host restriction factors (like HIV inhibiting APOBEC3)
cause direct + indirect cytopathic effect
change membrane permeability, inhibit host transcription/translation
induce apoptosis
induce immune complexes + viral carcinogenesis
what is innate + adaptive immune response to virus/infection
innate - type 1 IFN rapidly activated
adaptive - CD8T/Ab formed to provide long-term immunity
how do viruses promote onset of cancer
immunosuppression - HIV, kaposi sarcoma
chronic inflammation - HCV, HCC
cellular transformation - HPV, cervical cancer
what virus has direct cytopathic effect on neurons
VEE - vensezualan equine encephalitis virus
