Virophage Flashcards
what are virophages
small dsDNA viral phages that require the co-infection of another virus and its host (usually giant viruses)
when can virophages replicate / what are the two paths a virophage could take to get there
only when the giant virus is in bacteria as well / both viruses could infect the amoeba at the same time OR the phage integrates into giant virus chromosome
what are the two ways for progeny viruses to get out of a host cell
lysis and budding
what does lysis do / what is the main way of virus export
fills the host cell with virus and pops host cell to release all progeny / lysis
what does budding do / where does it happen / what do all enveloped viruses do to release progeny
viruses pass through the membrane of the host - the membrane lipids surround capsid to form an envelope / only happens in animal cells / bud from membrane (either cell membrane or organelle)
what key features of viruses does our body use to detect infection / why
nucleic acids because of the double stranded DNA and the double stranded RNA / the double stranded DNA is produced in the cytosol of host cell and we put our DNA in nucleus - we do not create double stranded RNA
what detects the dsRNA and dsDNA
pattern recognition receptors detect them in the cytosol and trigger the immune response
what does the binding of PRRs to dsRNA and dsDNA do / what do interferons do
initiated the production of cytokines called interferons / they induce Interferon Stimulate Genes (ISGs) on neighboring cells - renders them antiviral
how do interferons work
they bind to the interferon receptor which almost all cells in the body have - that expresses between 2-500 proteins (puts cell in antiviral state)
what are some of the proteins expressed by ISGs
RNAse (recognizes dsRNA and kills RNA in host cell), Protein kinase R (PKR phosphorylates components in translation to shut down translation in the cell), Cell death proteins (programmed cell death to remove replicative environment), MHC-I (promotes more expression of MHC-I proteins on membrane just in case cell already infected)
how do viruses avoid host recognition
keeping their capsid in tact until it contacts the nucleus and can directly deposit genome their AND reorganize the ER membrane to create viral factories that avoid detection in cytosol
what are the two groups of retroviruses / what is the difference
simple retroviruses and lentiviruses / simple cause tumors and leukemia, lenti cause infections that progress slowly over many years
what is an inherited virus called / what kind of viruses become inherited
an endogenous virus / retorviruses become inherited because they get fixed to parts of our DNA
can endogenous viruses cause infection / what are most cases of retrovirus replication
some can be activated and replicate to induce tumors - great majority do not / most are non-cytopathic (don’t kill host) and persistent
what is HIV / what kind of virus is it / how many major types are there
the human immunideficiency virus / a retrovirus (lentivirus) / two major types HIV-1 (most widespread) and HIV-2
