Antivirals

Question 1

Alpha Herpes viruses

Answer 1

HSV1 (oral ulcers), HSV2 (genital ulcers), VZV

Rapid growth, latency in sensory ganglia

Question 2

Beta Herpes viruses

Answer 2

CMV, HHV6, HHV7

Slow growth, restricted host range

Question 3

Gamma Herpes viruses

Answer 3

EBV (mono, Burkitt’s), HHV8 (Kaposi’s)

Oncogenic

Question 4

2d history of fever + confusion
New onset seizures
What is this likely to be and how should it be treated?

Answer 4

Herpes Simplex Encephalitis
Can be caused by HSV2 > HSV1
Emergency
Tx: High dose iv acyclovir

Question 5

HSV treatment

Answer 5

Acyclovir

Question 6

How does acyclovir work?

Answer 6

Guanosine analogue - substitute for guanine to block viral DNA replication by:
1. Higher affinity for viral DNA polymerase
2. First phosphorylation by viral thymidine kinase, second phosphorylation by host thymidine kinase
= Only activated in infected cells

Question 7

CMV treatment

Answer 7

IV Gancyclovir preferred
(Valgancyclovir prodrug can also be given - advantage is can be given orally as well as IV)
(Val)gancyclovir are BM suppressants - G-CSF can be given alongside
Foscarnet is 2nd line but nephrotoxic
Cidofovir is 3rd line but nephrotoxic (can be combined with probenicid to counteract nephrotoxicity)

Question 8

Pneumonitis in immunocompromised patient
Owl’s eye inclusions
Retinitis - Pizza sign

Answer 8

CMV

Question 9

How does gancyclovir work?

Answer 9

Guanosine analogue

Question 10

Post-transplant lymphoproliferative disease

Answer 10

EBV (EBV has high tendency to replicate within B lymphocytes - normally kept in check by immune system - in transplant sudden massive increase in B cells)
Tx: Rituximab (wipes out B cells)

Question 11

Influenza mechanism of infection

Answer 11

Haemagglutinin allows entry (hello) - binds sialic acid receptors on host cell
Neuraminidase allows release (nice job)

Question 12

Influenza Tx

Answer 12

Neuraminidase inhibitors - Oseltamivir (Tamiflu - oral) + zanamivir (Relenza - inhaler) - effective against Influenza A + B
N.B. Amantadine is another Tx but only effective against Influenza A

Question 13

Bronchiolitis Tx

Answer 13

• Usually self-limiting
• Ribavarin can be given orally
• Prophylactic Paviluzimab monoclonal Ab if pre-term, comorbidity, SCID

Question 14

Primary infection in childhood asymptomatic, resides lifelong in kidneys + urinary tract
Reactivates if immunocompromised
BMT - haemorrhagic cystitis
Renal transplant - Nephritis

Answer 14

BK virus

• Haemorrhagic cystitis = Cidofovir
• Nephritis = IVIG (cidofovir is nephrotoxic)

Question 15

Paediatric transplant patients

Answer 15

Adenovirus

Question 16

Progressive multifocal leukoencphalopathy

HIV

Answer 16

JC virus

Question 17

HSV resistance

Answer 17

Increasing resistance to acyclovir (and usually gancyclovir) due to mutation in viral thymidine kinase - fails to phosphorylate + activate
Willl remain susceptible to FOS or CDV as not guanosine analogues

Question 18

Used in severe resistant Herpes infections

Answer 18

Foscarnet

Question 19

Most common cause of acyclovir / gancylovir resistance

Answer 19

Viral thymidine kinase mutation