Antivirals Flashcards
(15 cards)
What are mechanisms of antiviral drugs
- block entry or exit
- interfere with nucleic acid
- interfere with virion assembley
- stimulate immunity
Why are antivirals used?
limit symptoms
hasten recovery
prevent transmission
reduce recurrence
What are the limitations of the influenza vaccine?
Reformulated yearly
annual re-vaccination needed
limited protection to NOVEL strains
Mechanism of Influenza A replication/infection
What are the 2 major surface glycoproteins?
Function of HA protein?
Function of NA protein?
What is the target of common influenza vaccines?
Influenza A - two major surface glycoproteins (HA - heamaaglutinin & NA neuraminidase)
HA protein - facilitates attachment to host cell sialic acid (cell wall) causes membrane fusion
NA cleaves the sialic acid - allows virion to exit host cell
TARGET HA - using binding antibodies - neutralises infection
Why is influenza so prominent in seasons?
Antigenic drift in influenza is characterised by?
Antigenic shift in influenza is charactertised by?
Selection pressure causes : constant mutation in HA epitopes (antigenic drift)
The segmented genome - means that there is potential for co-infection with more than one strain - this leads to reassortment (antigenic shift) and pandemics (example Spanish Flu)
Acting points of anti-influenza drugs
1st line?
Neuraminidase inhibitors action?
Baloxavir action?
Favipiavir action?
NA inhibitor: Stop the cleavage of sialic acid
Baloxavir: Inhibit viral protein synthesis
Faviparivir: Blocks RNA synthesis
Neuraminidase inhibitors
- Which illness?
- common name?
- What is it targeting?
- Which strains is it effective against?
- when is it useful to take this drug?
Neuraminidase inhibitors
- Influenza (strain A and B)
- Tamiflu
- Targeting surface protein (neuraminidase)
- useful in post exposure prophylaxis or flu season
How are Neuraminidase inhibitors given?
- name of each drug
When are they indicated?
- ?season
-?at risk groups
- time frame
Oral (oseltamivir)
Zanamivir (dry powder inhaler or IV or nebulised)
indicated if:
1. national surveillance indicates influenza is circulating
2. patient is in at risk group
3. within 48 hours of symptom onset (or 36 for zanamivir)
At risk groups
+65
immunosuppressed
any chronic condition
diabetes
pregnant woman
obesity (BMI >40)
children <6 months
What is baloxivir ?
What illness does it work on?
Broad action against which viruses?
What is it licensed for?
baloxivir = inhibits viral protein synthesis
Influenza strain A and B
Broad action against all RNA viruses
Licensed for post exposure prophylaxis within 48 hours
What is herpes labialis (pathology)
caused by?
Spread by?
Primary reinfection - symptoms? associated with other infection/signs such as?
Recurrence - signs? symptoms? resolution time?
Cold sores
Caused by herpes simplex 1 virus
spread by direct contact with lesions (asymptomatic shedding is frequent)
Primary infection: frequently asymptomatic - may experience pharyngitis, fever, mouth ulceration and lymphadenopathy
Recurrence: very common, classically - prodromal tingling - followed by localised painful blisters that resolve over 5-7 days
What is herpes genitalis?
Which virus is it caused by?
What are signs of primary infection?
What are the recurrence signs?
Herpes genitalis (genital warts)
caused by herpes simplex 2 (can be HSV 1)
primary infection: asymptomatic - may experience painful ulceration, fever, lymphadenopathy, urinary retention
recurrence: localised ulceration HSV-2 > HSV1
What is herpes simplex encephalitis?
How does it spread?
When can you catch it?
What are the symptoms? FFF
Severe life threatening infection of the CNS
Virus that spreads via neurons to the CNS
Sporadic (no seasonal occurance)
Fever, Fits, Funny behaviour
What is varicella zoster virus known as?
Sporadic infection - when is the peak of infection?
How does it spread?
When are people infectious?
Who is more at risk?
Immunocompromised results in?
Chickenpox
peak: spring/summer
RESPIRATORY DROPLETS and SHEDDING OF LESIONS
infectious 1-2 days before rash onset and UNTIL all lesions crusted over
Adults are more at risk of severe disease and pneumonitis
Immunocompromised results in disseminated infection
Where is primary infection site of chickenpox?
What causes the lesions around the body (spread)
?type of transport along neurons - leads to virus entering ?location for latency
What causes shingles (movement) : reactivate and ?type of transport to which region of skin?
Primary infection site: respiratory tract
primary viremia and seeding of the reticuloendothelial organs
secondary viremia : leads to disseminated to all tissues and skin and mucosal lesions
retrograde transport along neurones from skin permits entry into the spinal cord (latency)
reactivation and anterograde transport back to INNERVATED skin leads to zoster (shingles)
What is the target of antiviral treatment of HSV and VZV.
(example: Aciclovir, Valaciclovir, Famiciclovir)
Virally encoded enzymes are the target:
- Thymidine kinase
- DNA polymerase
