Diagnosis, Trmnt, Control, Prevention (Ex2)

Question 1

Explain the steps of PCR

Answer 1

• Denaturation: DNA sample is heated so it separates
• Annealing: twp primers attach to ends of the two DNA strands
• Elongation: Taq polymerase synthesizes new strands using the originals as templates, adding free nucleotides to the attached primers

Question 2

What is Real-Time PCR?

Answer 2

• also Quantitiative PCR
• allows monitoring and quantification of PCR products/nucleic acid load as the reaction progresses
• Uses fluorescent dye-labeled target probes, or other dyes

Question 3

What is genome sequencing?

What is the most commonly used method?

Answer 3

• the process by which the sequence of bases in a DNA molecule can be obtained and read
• Modification of the Sanger dideoxy method, involves using chain-terminating dideoxynucleotides

Question 4

Define Metagenomics

How is it done?

Answer 4

• the study of the collective set of microbial populations in a sample by analyzing the sample’s entire nucleotide sequence content
• amplification and sequencing of whole genome content of a given sample, followed by filtering and analysis of the data by comparing with genome databases

Question 5

What is Phylogenic Analysis?

Answer 5

• the use of virus genome sequence data to study evolution of viruses and genetic relationship among viruses

Question 6

Describe Microarrays

Answer 6

• thousands of known DNAs, amplified by PCR, are put onto a glass or chip
• target DNA are fluorescently labeled and added to the glass/chip
• positive reaction generate fluorescent signal

Question 7

Define Antimicrobial Chemotherapy

Answer 7

the treatment of infectious diseases by drugs that are inhibitory or lethal to the pathogenic microbe

Question 8

What is Acyclovir?

Answer 8

• antiviral against Herpesvirus
• administered as prodrug, requires virus enzymes in infected host cell to become active
• non-toxic to uninfected cells
• a synthetic nucleoside analong of deoxyguanosine

Question 9

Mechanism of Acyclovir

Answer 9

• enters virus infected cell, converted to monophosphate by virus enzyme
• host cell enzymes at 2 phosphates, making it triphosphate, and transport to the nucleus
• herpes simplex enzyme cleaves the 2 phosphates, making monophosphate
• herpes DNA polymerase incorporates the monophosphate into the growing DNA strands
• prevents growth: acyclovir monophosphate lacks attachment points for nucleotides

Question 10

What is Amantadine?

What does it do?

Answer 10

• synthetic tricyclic amine
• acts as antiviral and anti-Parkinsons drug
• inhibits replication of most strains of influenza A viruses by blocking un-coating of the virus

Question 11

Mechanism of Amantadine

Answer 11

• clogs the M2 ion channel in the endosomal membrane, and prevents it from pumping protons into the virion
• so the pH in the virion interior will not decrease
• viral RNAs remain bound to M1 protein, and cannot enter the nucleus when released from endosome

Question 12

What is Oseltamivir/Tamiflu?

Answer 12

a prodrug that, after its metabolism in the liver, releases and active metabolite that inhibits neuraminidase
- this slowing virus spread

Question 13

Neuraminidase and Hemagglutinin action

Answer 13

• HA binds to receptors containing sialic acid on host cell membranes
• after budding, HA of progeny influenza virions are still bound
• NA on virus will cleave the sialic acid and release HA
• the virus is freed from the infected cell

Question 14

What are the targets for anti-retroviral therapy?

Answer 14

• inhibit fusion
• inhibit reverse transcriptase
• inhibit integrase
• inhibit protease

Question 15

What is ZDV/AZT?

Answer 15

• nucleoside analog reverse transcriptase inhibitor

Question 16

Mechanism of ZDV/AZT

Answer 16

• phosphorylated by kinase in host cell into AZT-triphosphate
• reverse transcriptase cleaves 2 phosphates, and inserts AZT monophosphate into the cDNA
• blocks growth of cDNA because it has a N3 end instead of OH, so no other nucleotides can attach

Question 17

Effects of protease inhibitors on HIV

Answer 17

• inhibits proteases so HIV polyproteins cannot be cleaved into functional proteins
• HIV needs to cleave large Gag-Pol polyprotein, Gag polyprotein, and Env polyprotein
• HIV cannot mature, and noninfectious viruses are produced

Question 18

What is the purpose of immunization/vaccination?

Answer 18

• to protect susceptible individuals from infection or disease
• prevent transmission of infectious agents by creating an immune population

Question 19

What are the four Ws of immunization?

Answer 19

• Where: populations in endemic areas
• When: season or outbreak of non-endemic disease
• Who: population at risk
• Why: loss caused by disease must be greater than cost of immunization

Question 20

Live-attenuated Virus Vaccines

4 types

Answer 20

• vaccines produced from naturally occurring attenuated viruses
• 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 reassortments

Question 21

Non-replicating Virus Vaccines

2 types

Answer 21

• vaccines produced from inactivated whole virions

- vaccines produced from purified native viral proteins

Question 22

Vaccines produced by Recombinant DNA and related technologies
(4 types)

Answer 22

• vaccines produced by attenuation of viruses by gene deletion or site-directed mutagenesis
• subunit vaccines produced by expression of viral proteins in eukaryotic, bacterial, or plant cells
• vaccines utilizing harmless viruses as vectors for expression of other viral antigens
• vaccines utilizing viral DNA

Question 23

Explain DIVA

Answer 23

• differentiating infected from vaccinated animals
• vaccination with only live attenuated vaccines leads to production of an antibody response identical to that produced after natural infection
• subunit marker vaccines DIVA vaccines have only a portion of the pathogen, so if antibodies to other parts of the pathogen are detected, the animal has been naturally infected

Question 24

What are the 6 methods of vector control?

Answer 24

• source reduction
• biological control
• chemical control
• reducing contact potential
• protection of portals of entry
• decontamination

Question 25

Explain isolation

Answer 25

• applies to animals/people who are known to be ill with a contagious disease
• reduces probability of contact with a susceptible host
• not effective is shedding does not occur

Question 26

Explain quarantine

Answer 26

• applies to those who have been exposed to a contagious disease
• enforced for longest incubation period of the disease
• not effective for chronically infected healthy shedders

Question 27

What are the 4 methods of reducing contact potential?

Answer 27

• isolation
• quarantine
• population control programs
• quarantine and culling

Question 28

Define decontamination

Answer 28

• a process of treatment that renders a medical device, instrument, or environmental surface safe to handle
• includes sterilization, disinfection, and antisepsis

Question 29

Define sterilization

Answer 29

• describes a process that destroys or eliminates all forms of microbial life/pathogens, including highly resistant pathogens, such as spores
• no degrees, all or nothing

Question 30

Define disinfection

Answer 30

• a process that eliminates many or all pathogenic microorganisms, except spores, on inanimate objects

Question 31

Define antisepsis

Answer 31

• the application of a liquid antimicrobial chemical to skin or living tissue to inhibit or destroy microorganisms

Question 32

What are the 5 sterilization methods?

Answer 32

• moist heat (autoclave)
• dry heat (oven)
• chemical methods
• radiation
• sterile filtration

Question 33

What are the 5 areas of prevention and control in animal farms?

Answer 33

• farm biosecurity
• housing and management
• vermin and bird control
• purchasing policy
• people