Lectures 13-16 Flashcards
next generation sequencing
cheaper, quicker, needs less DNA, higher throughput, more accurate than Sanger sequencing
Metagenomics
study of the collective set of microbial populations in a sample by analyzing the sample’s entire nucleotide sequence and is a powerful method for random detection of existing and new pathogens
Genome sequencing plays a role in surveillance studies as it allows:
pathogen detection, studies on genetic variation, IDing of novel and undiscovered strains, development of diagnostics, IDing of genes associated with drug resistance, development of therapeutics, judging the efficacy of current vaccines and formulating new vaccine strategies
Phylogenetic analysis
the use of viral genome sequence data to study evolution of viruses and genetic relationships among viruses
Microarray
checking to see if sample DNA binds to known DNA probes attached to glass. Fluorescent signal indicates sample hybridization.
Allows the screening of LOTS of pathogens simultaneously
antiviral drugs
interfere with the ability of a virus to infiltrate a target cell or target different stages of replication/synthesis of components required for replication of the virus
immune system stimulation
interferons, class of proteins that has antiviral effects and modulate functions of the immune system
Acyclovir
administered as a prodrug. requires viral enzymes in infected host cell to convert into active form which interferes with viral replication
Synthetic nucleoside analog of deoxyguanosine
Acyclovir targets
herpes - humans
feline herpes-1 induced corneal ulcers
equine herpes-1 induced encephalomyelitis
acyclovir MOA
herpes DNA polymerase incorporates acyclovir monophosphate into the growing DNA strand as it was a G base. Further elongation not possible after this.
Acyclovir triphosphate competes with dGTP for viral DNA polymerase
Why doesn’t acyclovir target normal cells?
Acyclovir’s actions are through herpesvirus DNA polymerase - not found in normal cells
Amantadine
Inhibits replication of most strains of influenza A viruses by blocking uncoating of the virus
Amantadine MOA
M2 ion channel is the target. Amantadine particles block the channel to prevent it from pumping protons into the virion. In the presence of amantadine, viral RNAs remain bound to M2 and cannot enter the nucleus
Neuraminidase inhibitors
inhibitor of neuraminidase enzymes produced by influenza A and B viruses
Ex: oseltamivir (Tamiflu)
Neuraminidase inhibitors MOA
Blocking the function of neuraminidase with NA inhibitors is an effective way to treat influenza. This prevents release of virus and spread of infection as the hemagluttinin of virus is still bound/attached to the sialic acid containing receptors on the surface of the already infected host cell. Inhibition of neuraminidase therefore slows virus spread giving the immune system the opportunity to catch up
Nucleoside analog reverse transcriptase inhibitors (NRTIs) types
Zidovudine/Azidothymidine (ZDV/AZT)
Didanosine (ddI)
ZDV/AZT
Nucleoside analog of thymine. Causes competitive inhibition of reverse transcriptase activity - AZT-triphosphate competes with thymine deoxyribonucleotide tiphosphate for RT. Insertion of AZT-monophosphate into cDNA blocks the growth of the cDNA being transcribed from the viral RNA by RT.
AZT reduces CS in FIV-positive cats when administered at 10 mg/kg twice a day, subQ for 3 weeks
Protease inhibitors
drugs that inhibit proteases from cleaving viral polyproteins into functional proteins. Protease inhibitors bind to the active site of protease and thus the virus cannot mature and noninfectious viruses are produced
Live attenuated vaccine types
vaccines from naturally occurring attenuated viruses (cowpox for smallpox), vaccines produced by attenuation of viruses by serial passage in cultured cells, vaccines produced by attenuation of viruses by serial passage in heterologous hosts, vaccines produced by attenuation of viruses by selection of cold-adapted mutants and reassortants
non replicating virus vaccine types
vaccines produced from inactivated whole virions, vaccines produced from purified native viral proteins
Differentiating infected from vaccinated animals (DIVA)
subunit DIVA vaccines have only a portion of the pathogen in the vaccine (less antigens than normal). if antibodies are found to other parts of the pathogen –> animals has been infected with the pathogen
if only antibodies to the subunits are detected –> not infected
Isolation
applies to animals/persons who are known to be ill with a contagious disease
Quarantine
applies to those who have been exposed to a contagious disease (not effective with disease involving chronic shedders)
Decontamination
term used to describe a process or treatment that renders a medical device, instrument or environmental surface safe to handle
Sterilization
describes the process that destroys or eliminates all forms of microbial life/pathogens including highly resistant pathogens such as bacteria with spores
Disinfection
describes a process that eliminates many or all pathogenic microorganisms except bacterial spores on inanimate objects (less effective than sterilizing)
Antisepsis
application of liquid antimicrobial chemical to the skin or living tissue to inhibit or destroy microorganisms
Sterilization methods
Moist heat (autoclave), dry heat (hot air oven), chemical methods (gas - ethylene oxide, ozone), radiation (UV - non ionizing, Gamma and X - ionizing), sterile filtration (microfiltration)
Poxvirus family and subfamily
fam: poxviridae
sub: chordopoxvirinae
poxvirus properties
large, sometimes enveloped, DNA virus
mostly pleomorphic, typically brick shaped.
Irregular surface
Complex symmetry (not helical or icosahedral)
Core = dumbbell shaped
Genome = single molecule of linear dsDNA
many proteins encoded by the genome are for nuclei acid synthesis and virion structural components (also encodes things to evade immunity)
Parapoxvirus structure
ovoid, covered with surface tubules look like ball of yarn
