Theme 12
Rabies
Genus – Lyssavirus
Single-stranded RNA– easily develops mutants
Spread through saliva of animal (crosses mucous membranes in wounds)
Infects central nervous system of warm-blooded animal
Leads to death
Proliferates in PNS then moves to CNS (brain) and causes fatal encephaliDs
MulDplies in skeletal muscles – forms Negri body in brain stem
Furious (classical) vs paralyDc (dumb) rabies
Test – direct-fluorescent anDbody test (DFA) from brain or skeletal muscle
Primarily epizooDc but spread as zoonoDc to humans
Care within 48 hours – wash and disinfect wound / postexposure prophylaxis (Human
Diploid cell vaccine (0,3,7,14)/ Human rabies immune globulin (0))
Prevent by vaccine
Common cold
Sneezing, nasal secreDon, congesDon (NO FEVER)
Lead to laryngiDs and oDDs media
Treat symptomaDcally with cough suppressants and anDhistamines
Influenza
Influenzavirus – 8 RNA segments in outer lipid bilayer
Chills, headache, muscle aches, fever – no intesDnal symptoms
HA spikes (hemaggluDnin) – aYachment to cells / recogniDon. AnDbodies against flu are
directed at these. Cause aggluDnaDon in red blood cells (important for seroligcal tests)
NA spikes (neuramindase) – used to detach from infected cells and produce anDbodies (less
important than ones used to aYack HA)
HA and NA proteins numbered, each number represents great alteraDon in protein makeup
of spike
AnDgenic shi[ vs anDgenic dri[
RNA viruses – high mutaDon rates as they don’t have proofreading ability of DNA viruses
AccumulaDon of these changes leads to anDgenic dri[ (minor change in anDgenic makeup
that occurs in influenza viruses over Dme) – eventually allow viruses to avoid much host
immunity – virus sDll has same name (ie H2N2) but strains arise with minor anDgenic
changes
Viruses want transmission with minimal pathogenicity
AnDgenic shi[s are substanDal geneDc changes in influenza viruses leading to changes in the
H and N proteins – result in avoidance of most immunity developed in human populaDon –
responsible for outbreaks
Involves reassortment involving 8 segments of viral RNA
Swine are good vectors for reassortment
H1,H2,H3 infect humans – rest infect swine and poultry
Rabies
Genus – Lyssavirus
Single-stranded RNA– easily develops mutants
Spread through saliva of animal (crosses mucous membranes in wounds)
Infects central nervous system of warm-blooded animal
Leads to death
Proliferates in PNS then moves to CNS (brain) and causes fatal encephaliDs
MulDplies in skeletal muscles – forms Negri body in brain stem
Furious (classical) vs paralyDc (dumb) rabies
Test – direct-fluorescent anDbody test (DFA) from brain or skeletal muscle
Primarily epizooDc but spread as zoonoDc to humans
Care within 48 hours – wash and disinfect wound / postexposure prophylaxis (Human
Diploid cell vaccine (0,3,7,14)/ Human rabies immune globulin (0))
Prevent by vaccine
Common cold
Sneezing, nasal secreDon, congesDon (NO FEVER)
Lead to laryngiDs and oDDs media
Treat symptomaDcally with cough suppressants and anDhistamines
Influenza
Influenzavirus – 8 RNA segments in outer lipid bilayer
Chills, headache, muscle aches, fever – no intesDnal symptoms
HA spikes (hemaggluDnin) – aYachment to cells / recogniDon. AnDbodies against flu are
directed at these. Cause aggluDnaDon in red blood cells (important for seroligcal tests)
NA spikes (neuramindase) – used to detach from infected cells and produce anDbodies (less
important than ones used to aYack HA)
HA and NA proteins numbered, each number represents great alteraDon in protein makeup
of spike
AnDgenic shi[ vs anDgenic dri[
RNA viruses – high mutaDon rates as they don’t have proofreading ability of DNA viruses
AccumulaDon of these changes leads to anDgenic dri[ (minor change in anDgenic makeup
that occurs in influenza viruses over Dme) – eventually allow viruses to avoid much host
immunity – virus sDll has same name (ie H2N2) but strains arise with minor anDgenic
changes
Viruses want transmission with minimal pathogenicity
AnDgenic shi[s are substanDal geneDc changes in influenza viruses leading to changes in the
H and N proteins – result in avoidance of most immunity developed in human populaDon –
responsible for outbreaks
Involves reassortment involving 8 segments of viral RNA
Swine are good vectors for reassortment
H1,H2,H3 infect humans – rest infect swine and poultry
