paleovirology 1+2 Flashcards
what is an integrated virus called
provirus
endogenous viruses in vertebrates
endogenous retroviruses
effects ERVs might have
shaped some aspects of immunity
seems to cause disease in some contexts- e.g. in sheep, there was talk of one contributing to ME but hard to separate cause and effect
how do ERVs form their ‘fossil record’
different mutation rates to hosts, makes them easy to identify and can track down likely times of integration
RELIK
endogenous lentiviral lineage in rabbits- unusual, they don’t normally integrate
how has analyses of RELIK given us info about lentivirus infections?
present in rabbits and hares but not pikas- therefore know the age of the viral relic
what did RELIK teach us about lentiviruses?
at least 12 million years old, older than current estimates
other endogenous lentiviruses
pSIVgml, a transitional form in SIV evolution
how old have analyses of the SIV lineage predicted the virus to be?
3.5my old
what theories of origin are consistent with the age of SIV?
all of them, so can’t really discriminate- ancestral codivergence, ancestral transfer via a terrestrial route before Madagascan landmass split off, flying vector transfer
ways to study paleovirology other than bioinformatics
reconstruction- adding virus bits that are lost, helps study encoded proteins etc and compare structure with extant viruses
another example of genome invasion time being identified
SloEFV (foamy virus)- 40ish my old virus in sloths
can be aligned with timing of continent formation and separation of mammals by looking at coevolution between virus and mammal species
why are non-retroviruses less likely to integrate into the genome?
genome integration is not an obligate step
how can non-retroviral DNA get integrated into the genome?
non-homologous recombination of DNA viruses, mRNA interaction with cellular retroelements
example of a primate non-retrovirus integration
bornavirus, integration around 40mya- human version makes mRNA
how many types of virus (in terms of nucleic acid type) have been seen as EVEs?
all of them
how can we tell if a viral element is functional?
simulating evolution under neutral circumstances and comparing to reality- e.g. in bornavirus, found no stop codons where under neutral evolution we would expect 15ish
term for antiviral factors derived from viruses
EVE derived immunity (EDI)
when do we think bornaviruses originated?
93mya, in the mesozoic
when do we think circoviruses appeared?
68mya, mesozoic
correlation between body mass and ERV acquisition
larger body mass tends to lower ERVs- possibly because less defence against insertional mutagenesis?
correlation between body mass and age of ERVs
larger mass > older ERVs
body size and retroviral activity
larger body size > lower retroviral activity
