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66 Cards in this Set

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How and when did Rabbits spread through Australia
They were introduced in 1788 and spread at a rate of 70 miles per year till they reached the indian ocean!
How where the rabbits a problem?
The rabbits were overpopulated and became a huge ecological problem as they consumed trees, tree bark, grass and drove out marsupials
What was Phillip Island?
Bunnies turned it into a wasteland, but once they left it was lush and green!
What was a silly technique they tried?
Who was Sanarelli
He went to Montevideo to set uo Hygiene Institute. He brought bunnies which were needed to make the sera for vaccines, but soon they all died?
What caused the death of Sanarelli's rabbits?
A pox virus known as myxoma which is related to small pox and causes myxomatosis.
Discribe Myxomatosis
It is a yucky disease that causes legions and easily spreads from rabbit to rabbit. It can also be carried by misquitoes.
Why was myxoma introduced in Australia?
As a potentila control unit for rabbits
What happened with rabbit deaths once myxoma was introduced?
Rabbits quickly died off but then the death rates declined and over four years the disease became less potent
What happened to the strains of myxoma?
Initially the strains were very virulent but gradually they became less virulent with virulence decreasing over time. Started with lots of class I, but than got more variety and eventually came to equilibrium with alot of CLass III
Aside from virulence what might also have impacted rabbit deaths?
The rabbits themselves were becoming resistant through the evolutionary principal of natural selection
Is myxoma still an effective control agent?
Did other countries use the same approach as australia?
Yep England and France experienced similar results
What is fitness?
Defined by the number of offspring an individual contributes to the next generation, consists of survival and fecundity
What is evolution?
A change in gene frequency, genes that encode for a beneficial triat will increase in frequency, natural selection can only work with what there is
When will natural selection occur?
fitness is related to some phenotypic trait, phenotype trait has a heritable genetic basis, individuals in the population differ in this pheotypic trait and the genes that code for it
What will happen with awesome genes over time?
genes that result in a higher fitness will increase in frequency
Why is a virus a powerful agent of natural selection?
Because the immune system must fight off that virus and since people have different genes viruses help select
What is the life cycle of the pox virus?
binds to cell or is endocytosed, the viral CORE particle with the genome, rna polymerase and enzymes are released into cytoplasm, early genes are T&T, the viral CORE translocates to the nulcear envelope,,the viral nucleoprotein complex containing the genome is released and the genome replicates, Viral Late Genes are T&T, studd is packaged to make immature virons, IVs marture into IMVs and migrate to the edge where they are exported
What is the viral genome?
linear DNA
When will a virus have higher fitness?
If it grows and reproduces more quickly so in the host this virus is awesome
Why is individual virus fitness not the best?
Well the virus may kill the host to fast which decreases the amount of time the virus can be passed on so its not so hot...its better for the species to have a good fitness by having a mid-virulence
Why does host death rate decrease?
Evolution of host and pathogen
What is the other aspect of fitness for a pathogen?
How well it is passed onto the next host...virus selection occurs at a group level
What is linked to mortality?
higher growth rate
What are some interesting facts about TB?
One of the most serious reemerging bacterial diseases, affects 1/3 of world, one of the three main killers
What type of pathogen is TB?
Where did TB come from?
It was probably a soil bacterium that evolved to infect cows then jumped to human 10,000 years ago
What is interesting about TB that might make it difficult to test for?
It is very slow growing and only doubles ever 18 to 24 hours, this also porbably accounts for its chronic nature
Is TB always active?
Nope it can be latent alot of the time!
Who identified TB?
What bacterial characteristics define TB?
Aerobic, non-motile rod, acid-fast bacteria
What is acid-fast?
a bacteria which has distinctive staining properites because it has a unique lipid component in the membranes termed mycolic acids which only exist in mycobacteria, they have a gram positive cell structure, but do not readily stain because of the lipids on the surface
How does TB spread?
through droplets that result from coughing, talking, sneezing...consequently its worse when there is poor ventilation and crowded spaces
What type of precaution might a healthcare worker take?
Patients are in negative pressure rooms and there are masks too
What are the symptoms of TB?
A cough cloudy mucus sometimes with blood, fever chills
Where do the bacteria reside?
In the lower part of the respiratory tract
What is the TB test
will result in skin inflammation as the result of an accelerated response from teh immune system due to previous exposure
What is the bacteria and how does it cause TB?
M tuberculosis gets taken up macrophages which form tubercles which grow and grow, the lungs start losing function as their capacity is decreased and ultimately the lungs are consumed
Is there a good vaccine for TB?
Not really. A vaccine was made from weakened strains in cows, but it isn't recommended in the US because there are few incidences in the us, it can interfere with the test, and differs in children and adults
How did the treat TB circe moulin rouge?
fresh air and country side confinement
What is DOTS?
Directly observed treatment in which patients are given a variety of drugs over 6 to 18 months with the hopes of stopping the disease by targeting at least one weak spot and not allowing it to come back
Why do the homeless pose an issue?
Because they are difficult to reach and hard to be compliant
What was the first drug for TB?
Where can antimicrobial agents be produced?
in the soil
What is the Central Dogma?
DNA to RNA to Protein
What are the different types of drugs and what do they target?
CEll walll synthesis, Quinolones (dna gyrase) target DNA rep, RNA rep, DNA by RNA polymerase, 50s inhibitors (protein synthesis), 30s inhibitors (protein synthesis), tRNA/ protein synthesis, Folic acid, cytoplasmic membrane structure
What is a prodrug?
Most be activated by enzyme in the bacteria itself
What is Isoniazid?
A prodrug that requires activation by catalase-peroxidase encoded by katG, resistance most often due to mutation in katG
What is molecular target of Isoniazid?
InhA, an enoyl-ACP-reductase involved in biosynthesis of mycolic acids, also ndh a gene that encodes for NADH hydrogenase
Where can resistance come from with Isoniazid?
targets itself is INHA interferes with lipid layer in mycobacteria
IT looks alot like nicotinamide and therefore involved with NADH
What is a typical first line drug?
Rifampicin which inhibits transcription by interfering with the beta subunit of RNA polymerase, resistance is mediated by mutation
Why is there normally a combination of second line drugs?
because many strains of TB are MDR
Do we quarantine people for XDR?
When would we like to elimate TB by?
What is the plan for stopping TB?
accurate diagnosis, better drugs and vaccines
Kirby Baur Test?
Observes sensitivty of bacteria to an antiobiotic, grow them one a cultre and find zones of inhibition
What are resistance mechanisms?
Modify the chemical structure and won't work anymore, reduced permiability, antibiotic is inactivated, target altered to resist action, substitute pathways, antibiotic is pumped as with tettracycline
What is a plasmid?
Double standed DNA that is small and replicates independently from the chromosome, pass from one bacteria to another
Tetracycline does what?
often efluxing back out through a protein pump
What is correlated to antiobiotic use?
Antibiotic resistome
every isolate was reistance to 6 or 8 agents which makes us wonder how far stuff is going
What can degrade rifampicin?
An enzyme
What does microbes that synthesize antiobiotics have?
Sophisticated mechanisms to protect themselves against their own toxins
What is ecology?
The study of the natural environment particulary the interrelationships between organisms and their surrounding
What do we need to think about when studying a disease?
Its limitations and where it can and canot grow