viral properties and disease Flashcards
zoonoses: define the terms zoonosis and host range, explaining how viruses emerge and re-emerge using named examples
define zoonosis
disease that can be passed to humans from animals
define host range
range of host cells that an individual strain of virus is susceptible to
define quasispecies
created due to selection pressure within host; every single mutation at every single position in genome
effect of bottleneck on quasispecies
at point of transmission; reduce diversity of viral genomes; at point of bottleneck appear very similar
what shows branching of quasispecies
biogenetic tree
3 features which increase evolution of drug resistance virus variants in response to selection pressure
high mutation rates, large progeny numbers, short replication time
what can influence whether drug resistant viruses proliferate
relative fitness of drug resistant virus compared to wild virus
antibodies as evolution selection pressure
neutralising antibodies either actively or passively acquired can prevent viruses entering cells, but also select for those in the quasispecies that have antigen mutations unsusceptible to antibodies
define antigenic drift and impact on vaccinations
gradual evolution of virus driven by antibody selective pressure; necessitates yearly update to vaccine
5 global influences on emerging infections
world population increasing, climate change, travel increasing, immunosuppressed humans, farming practices and monocultures
what are arboviruses
+ve sense RNA genome which is transmitted to humans via arthropods such as mosquitoes
why is HIV targeted with many drugs
to prevent resistance developing
why are arboviruses on the increase
global warming, poor mosquito control, stagnant water in cities, dams and imports/exports spread mosquitoes
how was transmission from Israel to NY detected
RT-PCR
what is dengue carried by and what is its usual host
mosquitoes; monkeys
