Modern antiviral drugs Flashcards
Most antiviral drugs are taken by
Inpatient population. Especially the transplant patients. Most at risk due to immunosuppression.
How to prevent viral infections in present time
Prophylactic drugs and continuous monitoring with PCR
What is combination therapy
The use of a combination of drugs to combat the high rate of mutations that confer resistance to viral strains.
Example
Drug A selects for resistant gene once every 10^4 genomes
Drug B selects for resistant gene once every 10^5 genomes
The combination of the two drugs would mean that resistance gene is selected once every 10^9 genomes.
During single drug therapy, what happens to the viral load?
At first plummets. Then, since the drugs have selected for a resistant gene, the resistant stain grows in population.
Do drugs act as positive or negative selection for resistant genome?
Positive selection
What does low resistance barrier mean?
This means that the a single point mutation in the virus can confer the virus resistance to the drug
How do some viruses have a low resistance barrier?
High turnover of the viruses gives them low resistance barriers
How come mutations happen to easily in HIV?
Due to the low fidelity of reverse transcriptase
What is an accessory mutation?
Accessory mutations ensure the fitness of the virus. Mutations in the genome can alter the function of a protein that may be vital for the survival of the virus. If so, accessory mutations make sure the protein function is replaced by another gene and so fitness is maintained. The more mutations are required to create a resistant strain, the more likely fitness is hindered. In other words, fitness cost is enhanced.
Do all drugs have low genetic barriers?
No. Some require more complex mutations and some require accessory mutations.
Whys is the likelihood of single antiviral drug therapy working for HIV slim?
Since its very easy for viruses to acquire mutations.
What is HAART?
Highly active antiretrovial therapy.
Life expectancy increased and mortality decreased once implemented to treat HIV.
Uses a combination of antiretrovirals.
What is PREP?
Pre exposure prohylaxis.
Taken by HIV negative partners who engage in sexual contact with HIV positive partners to prevent transmission.
Can be developed into microbicidial gels.
What is TRAP?
Treatment as prevention.
Use of antiretroviral drugs suppresses viral load to the point it is undetectable.
96% reduction in HIV-1 transmission.
Can HIV be cured?
Not with modern antiretrovirals.
Does not target the latent viral load in inactive CD4 cells. Once activated, the CD4 transmit the viruses. Since drugs target replication, has no effect on inactive CD4 cells.
Does not target persistent viral repertoires in some active CD4 cells.
