Microbiology 21 - Antivirals Flashcards
What is the mechanism of action of acyclovir?
Guanosine analogue that prevents elongation of DNA
Activated by viral thymadine kinase
Which viruses is acyclovir particularly useful for?
VZV
HSV 1 + 2
Which antiviral is used in HSV encephalitis?
High dose IV acyclovir
Start empirical treatment immediately if suspected. If confirmed, treat for 14-21 days.
What is ganciclovir used for?
Pretty much only for treatment of CMV in the imunocompromised and neonates
What is the main side effect of ganciclovir?
Bone marrow toxicity
Avoid in bone marrow transplant patients. Use foscarnet instead
When is foscarnet used?
To treat CMV in patients where ganciclovir is contra-indicated (eg neutropaenic patients)
It is nephrotoxic though
Which antiviral is most useful for treating RSV (bronchiolitis in children)?
Ribavarin - but there is a lack of good evidence for its efficacy
What drug is given to infant groups at high risk of RSV?
Palivizumab
E.g infants with bronchopulmonary disease, SCID etc.
Which antiviral is most useful for treating haemophagocytic lymphohistiocytosis in covid?
Anakinra (IL-1 receptor agonist)
What is the best treatment for paediatric adenovirus infection?
Combination of cidofovir and IV Ig
What treatment can clear chronic hep B in 3-7% of patients?
48 week course of pergolated interferon gamma
Owl’s eyes inclusion bodies:
Owl’s eyes cells:
CMV infection
Reed-Sternberg cell (Hodgkin’s Lymphoma)
Which antiviral drug does not require activation by viral kinase
Foscarnet, Cidofovir
Ganclicovir needs viral kinase to be activated
What is letermovir?
New CMV prophylaxis drug that can be used in bone marrow transplant patients.
It is a CMW DNA Terminase inhibitor
Two main important surface proteins in influenza virus?
Haemagglutinin: Helps viral entry into cells
Neuraminidase: Helps virus to budd/cleave off
Oseltamivir (Tamiflu) MOA:
Directly inhibits the viral neuraminidase
Prevent release of new viruses from the cell.
Disease caused by BK virus and treatment?
Haemorrhagic cystitis (treat with intravesicular cidofovir)
Nephropathy (treat with IVIG- cannot use cidofovir as it is nephrotoxic)
Foscarnet and cidofovir MOA and toxicity?
Inhibits dna polymerase (guanine/base pair analogues that insert into dna and terminate its prolongation)
Nephrotoxic
Used when ganciclovir is C/I such as in bone marrow transplant patients
Not dependent on viral kinases so other drugs like aciclovir (dependent on viral thymadine kinsase- immunocompromised people with HSV quickly develop resistance) or ganciclovir might get resistance patterns but then we can use foscarnet or cidifovir
