Viruses 4 Flashcards
6 steps of viral replication?
Attachment
Uptake
Uncoating
Replication of the viral genome, transcribe and translate
Assembly
Release
Outcomes of viral replication?
Destruction of the host cell
Elimination of the virus from the host w/o issue to the hist
Survival of host with virus carried in a dormant state
Transformation of the host cell and survival of it in an abnormal state
What type of cell may a cell transform into after a viral infection?
Cancerous
Proportion of cancers that are caused by oncogenic viruses?
20%
Example of a virus that may cause a cancer?
Gardasil HPV vaccine
Why may a virus be able to interact with a certain group of tissues/cells but not another group?
They only have the correct receptors for certain groups
Viral cellular/tissue/host tropism?
Viruses can only infect certain cells/tissues/hosts
Papilloma virus tropism example?
They show tropism for epithelial cells
First step of group 1 DNA virus replication life cycle?
Virus enters the cytoplasm and is uncoated at the nucleus
What follows uncoating of a group 1 virus at the nucleus in its DNA virus replication life cycle?
The viral DNA enters the host cell nucleus and is transcribed and translated by the host cell RNA polymerases
What happens after group 1 viral mRNA is made?
viral mRNA is moves to the cytoplasm and directs the synthesis of viral proteins
What can some viruses (such as HPV) do following production of viral particles?
Integrate themselves into the host genome
What could a virus inserting itself into a host genome result in?
Gene disruption and transformation of the host cell to a cancerous state
HPV integrating into the host genome?
Happens in basal epithelial cells–> can damage DNA and activate oncogenic factors
First step of an RNA virus life cycle?
Viral genome directs the cell to produce an RNA dependent RNA polymerase
What does the RNA dependent RNA polymerase do?
Converts +ve sense RNA genome to -ve sense (to be used to make mRNA)
What does the RNA dependent RNA polymerase allow for?
Production of more copies of the +ve sense genome, and copies of mRNA
Which organelle isnt used in +ve sense, ssRNA viruses (group 4)?
The nucleus, as there is nothing there that could be used
How can +ve sense ssRNA viruses make the RNA dependent RNA polymerase?
They have +ve sense ssRNA, which can be used as mRNA to make the RNA pol
First step of an RNA retrovirus (group 6) life cycle?
Virus synthesises reverse transcriptase, and packages it in the capsid w/ the viral genome
WHat happens following uncoating of an RNA retrovirus in the cytoplasm?
viral RT makes dsDNA from the viral RNA genome
What happens to the dsDNA after it is made using RT in the replication cycle of an RNA retrovirus?
The dsDNA is integrated into the host genome, promoted by viral encoded integrase genes
What happens after integration of dsDNA into the host genome in a RNA retroviral life cycle?
Replicates quietly, and at a low level–> long time
How does HIV initially replicate and release its particles?
Replicates slowly and releases via budding–> doesn’t kill the host cell
