Evoloution And Medicine Flashcards
Outline HIV AIDS
HIV is a lentivirus that causes aids
Infection occurs through bodily fluids
Virus infects and causes the failure of the immune system
Death due to pathogens that are now able to colonise you due to no immune system to fight them off
Outline phylogenies trees
Phylogenetic trees trace the relationships between species.
Can also be used to trace DNA or protein sequences
Outline the tree of HIV sequences
Multiple sequences from from arch patient
These sequences are more closely related within a patient than between (in most cases)
Outline the evidence for and against the multiple virus theory for HIV
Evidence for: Multiple sequences, infection from a bulk source
Evidence against: the pattern of the tree - Viruses within patients being more similar than between patients does not evidence infection by multiple viral sequences.
Outline the evidence for and against the viruses chaining theory for HIV
Evidence for: Viruses within a patient are more similar than between patients. The pattern of the tree suggest a single point of entry, and then viral diversification
Evidence against - specific individual has virus in two parts of tree
What Is the prediction for testing for viruses changing method
Prediction: If the viruses are changing then if we sample a patient successively then we should see different viral sequences appearing
What is a proximate explanation
By what mechanism is the change occurring
What is an ultimate explanation
What is causing the change
Outline the infection cycle of HIV
HIV virion containing 2 copies of RNA gnome binds CD4 and chemokine co receptor on cell surface.
Fusion: Viral core inserts into cell
Reverse transcription of viral RNA genome into DNA
Nuclear import into nucleus, where integration into genomic DNA occurs
Transcription of viral RNA
Translation of viral proteins
Assembly of viral proteins and viral genomic RNA
Budding of virus from cell, and maturation
Outline reverse transcription in terms of HIV
Reverse transcriptase is an enzyme that turns RNA sequence back into DNA
The HIV genome is RNA, but is turned into DNA to insert into host genome
Reverse transcription is more error prone than DNA replication, resulting in many variants
Why is reverse transcription more error prone
DNA polymerase has proof reading function, hence errors are corrected during DNA transcription
There is no proof reading capabilities of reverse transcriptase. Thus more mistakes are left un repaired, and
What 4 things are required for natural selection
Variation, Inheritance, Selection, and Time
What are the consequences of HIV evolution
HIV genome holds the record for the fastest evolving thing we know of.
Patients don’t have a virus, they have a vast Amanda oof viral variants.
Resistance to simple and even complex therapy arises.
Results in making effective vaccines very hard
Outline the HIV armada
Estimates of 10^8 to 5x10^10 provirus (virus inserted into genome) containing cells in a patient
Each one may be genetically distinct, so assuming 1 provirus per cell, patients may have up to 5x10^10 different variants
