viral infections Flashcards
viral transmission
aerosol, contact, droplet, vector, fomite,
waterborne, bloodborne, foodborne,
vertical
replication of virus
dependent on virus ability to invade the host cell (obligatory intracellular microbes)
viral evasion of host defences
mutations
latency
immune suppression
rapid replication
structure of a virion
enveloped vs non-eveloped
essential enzymes
capsid protein layer
viral genome
Antigenic drift
minor change
* due to small mutations in surface proteins
* previous infections may offer partial protection
* potential to cause epidemics
Antigenic shift
major change, rapid
* can produce completely new viral sub-types
* associated with Influenza A viruses which have a broad host range (humans, birds,
mammals)
* potential to cause pandemics
HA of influenza
hemagglutinin
allows binding to + entering of respiratory epithelial cells
NA of influenza
neuraminidase
releases new virions from infected host cells
enveloped virus
outer lipid layer that contains crucial glycoproteins (spikes) for attaching to + entering host cells
(i.e., influenza viruses, herpesvirus, coronaviruses)
non-enveloped virus
more resistant to environmental conditions such as temperature, pH, + detergents
(i.e., poliovirus, rhinovirus, adenoviruses)
drugs for influenza
oseltamivir (PO)
zanamivir (inhalation)
MOA of oseltamivir
NEURAMINIDASE INHIBITORS
Viral latency of HSV
in dorsal root ganglia (lifelong)
treatment of HSV
acyclovir
Post-herpetic neuralgia of VZV
Neuropathic pain persisting in a dermatome at least 3 months after lesions have resolved
Common complication of herpes zoster
Topical or systemic pain relief often required
Early antiviral initiation can reduce incidence + severity
MOA of acyclovir
nucleoside analogs
inhibits synthesis of viral DNA = inhibition of viral replication
adverse effects of acyclovir
nephrotoxicity
neurotoxicity
DRESS with valacyclovir (drug reaction with eosinophilia + systemic symptoms),
TTP/HUS with valacyclovir (thrombotic thrombocytopenic purpura/hemolytic uremic syndrome)
valacyclovir prodrug of
(prodrug of acyclovir, ↑ bioavailability) (PO)
famciclovir prodrug of
prodrug of penciclovir
Primary genital HSV infections risk _________transmission, during
treatment and prophylaxis
Primary genital HSV infections risk vertical transmission, especially in the 1st and 3rd trimesters, and should be treated with acyclovir.
Prophylaxis with acyclovir or valacyclovir from 36 weeks until delivery is indicated if there has been a prior infection within the past year
