12. Lecture

Question 1

Resistance of viruses to environmental conditions

Answer 1

• dehydration - enveloped viruses
• high temperature - protein denaturation (180°C, 120°C, 70°C, 56°C)
• radiation (UV, gamma) - damage of the nucleic acids
• ionic environment
- optimal: pH 6.5 – 7.5
- limits: pH 2 – 12

Question 2

disinfectants

Answer 2

•acids and bases (0.1M H2SO4
, 3% NaOH)
•oxidants (H2O2
, KMnO4
)
•halogenids (iodine, chlorine, hypochloric acid, bleach)
•protein denaturants (ethanol)
•detergents, lipid solvents (chloroform, sodium deoxycholate)
•aldehydes (3% formaldehyde)

Question 3

inactivating agents

Answer 3

• 0.001% formaldehyde

* nucleic acid denaturants (EI, BPL)

Question 4

antiviral medicaments

Answer 4

No broad spectrum antiviral agents ↔ antibiotics(bacteria)

Question 5

effects of antiviral medicaments

Answer 5

•inhibition of virus replication
•decreasing the virus shedding
•localization of the infections
→ But the infection remains

Question 6

effects of antiviral medicaments

Answer 6

•close contact between virus and cell activity
•effective drugs are often toxic for the cells
→ specific agents are needed
•high viral mutation ratio - resistance

Question 7

First generation nucleoside analogues

Answer 7

antiviral drug
•incorporates into the nucleic acid
•more or less toxic – external use
•Iodoxuridine (IDU), Trifluorothimidine (TFT)
Adenine-arabinoside (Ara-A)
→ topic ointments against herpes simplex

Question 8

Ribavirin

Answer 8

antiviral drug
•guanosine analogue (First generation nucleoside analogue)
•mRNA guanyltransferase inhibitor
•against orthomyxo-, bunya-, arenaviruses

Question 9

Second generation nucleoside analogues

Answer 9

antiviral drug
•activated by virus specific enzymes
•more selective to viral polymerase than to cellular

Question 10

Acyclovir

Answer 10

antiviral drug
•guanine derivate – acyclic „deoxyribose”
•viral TK enzyme phosphorilates
•selective to viral polymerase
•exonuclease does not remove
→ chain termination!!!

•effective against Herpes simplex virus-1, -2, and
Varicella-Zoster virus, but not against cytomegalo virus

Question 11

Zidovudine

Answer 11

antiviral drug
•reverse transcriptase (RT) inhibitor
•ATZ-TP is competitive to dTTP
•RT has no repair activity
→ chain termination
•Effective against retroviruses (HIV, HTLV)

Question 12

•Non-nucleoside RT inhibitors

Answer 12

antiviral drug
RT=reverse transcriptase
•directly inactivates RT
•Efavirenz, Delavirdine...
•active against HIV-1
•used in combination therapies

Question 13

Protease inhibitors

Answer 13

antiviral drug
•inhibits retroviral protease
•fits into the active center of the enzyme
•the cleavage of the precursor polyprotein is inhibited
•Ritonavir, Indinavir…
•effective against HIV

Question 14

•Favipiravir (T 705, Avigan)

Answer 14

antiviral drug
• RdRp inhibitor
• lethal mutations
• broad spectrum

Question 15

Methisazone

Answer 15

antiviral drug
•viral polymerase inhibitor
•against pox-infections
•poor solubility

Question 16

Amantadine, Rimantadine

Answer 16

antiviral drug
•ion channel inhibitor
•uncoating is defected
•against influenza

Question 17

Neuraminidase inhibitors

Answer 17

• Oseltamivir (Tamiflu)
• Zanamivir (Relenza)
• against influenza

Question 18

antiviral drug use in vet. care

Answer 18

Use in veterinary practice is very rare!
•expensive
•narrow spectrum
•resistance occurs

Question 19

Interferons, interferon inducers

Answer 19

•high efficacy
•not antigen specific
•short effect
•parenteral administration
•expensive (species-specific)
•progressive hypo-responsiveness
→ Presently rarely used in veterinary practice

Question 20

Immune sera and purified immunoglobulins

Answer 20

• passive immunization
• short term protection
• danger of serum-sickness or anaphylaxis
• large animals: enormous doses
• high costs (hyperimmunization)
• mainly in pet practice