Common RNA Viruses (Barr)

Key Takeaways

Genome Polarity

• Positive-Sense

• Negative-Sense

+

• Directly translated by ribosomes

• Infectious as naked RNA

• No need to package polymerase

-

• Cannot be translated directly

• Must be transcribed to + mRNA first

• MUST package own RdRp polymerase

  • This is a drug target (ex. Ribavirin)

Paramyxoviridae Synctium Formation

• F protein → Syncytia Formation (multinucleated giant cells)

  • F (fusion) protein is on all viruses causing host cell membranes to fuse together

  • Multinucleated giant cells on histology + immune evasion

    • Virus spreads directly cell to cell, avoid extracellular space & antibodies can’t reach

Which RSV product can be given to all infants <8 months

Nisrevimab (mAb)

Which RSV product is a maternal vaccine and can be given to adults ≥60 yo

Abrysvo

• Pregnant 32-36 weeks

• Adults ≥60 yo

Rabies PEP Protocol

1. Immediate wound wash; soap + water x 15 min

2. HRIG (20 IU/kg): infiltrate around wound day 0

3. Killed Vaccine: Days 0,3,7,14; IM deltoid only & add Day 28 if immunocompromised

When is rabies virtually always fatal

Once neurological symptoms appear

Naked capsid viruses (enteroviruses, norovirus) resist alcohol sanitizer

What do you use instead

Soap + water or bleach

Clinical sign of Rhinovirus

• Optimal temp 33°C

  • Temperature biology confines rhinovirus to upper airway

  • Does not replicate at 37°C

Norovirus Kaplan Criteria

• Vomiting in >50% of cases

• Mean incubation 24-48 hours

• Mean illness duration 12-60 hours

• No bacterial pathogen

Food handlers must stay off work for 48 hours after symptom resolution