General Virology + Coronavirus + Rabies Virus (high-yield summary)

1) General virology

• Genome type: DNA vs RNA, single-stranded vs double-stranded, positive vs negative sense
• Capsid symmetry: icosahedral, helical, complex
• Envelope: present vs absent
• Replication strategy and tissue tropism
  (Source: Harrison’s, p. 5478)

1. Attachment to host receptor
2. Entry (fusion/endocytosis/injection)
3. Uncoating
4. Genome replication + protein synthesis
5. Assembly
6. Release (lysis or budding)

• Enveloped viruses: fragile in environment, spread via droplets/fluids, inactivated by detergents
• Non-enveloped viruses: more stable on surfaces, often fecal-oral spread
• Viral diseases can result from direct cytopathic effect and/or host immune injury

2) Coronavirus (focus: SARS-CoV-2, plus family basics)

• Enveloped, positive-sense single-stranded RNA virus
• Structural proteins include:
  • S (spike): receptor binding and cell entry
  • M (membrane)
  • E (envelope)
  • N (nucleocapsid)
• Spike S1/S2 regions are key for receptor interaction and fusion

Image (structure/lifecycle context):

(Source image dataset: Hugging Face PMC clinical VQA raw)

• Range: asymptomatic to critical illness
• Common features: fever, cough, dyspnea, fatigue, myalgia, anosmia (variant-dependent)
• Severe disease: viral pneumonia, hypoxemic respiratory failure, ARDS, thromboinflammatory complications

• Nucleic acid amplification tests (RT-PCR/NAAT) are central in diagnosis
  (Referenced in Surviving Sepsis Campaign COVID guideline references, p. 26)

• Mild: supportive care, risk stratification
• Moderate/severe: oxygen strategy, anti-inflammatory and antiviral treatment per current protocols
• Critical: ICU-level organ support, thrombosis prevention, evidence-based sepsis/ARDS care pathways
  (Sepsis-COVID guideline reference list shown on p. 26)

3) Rabies virus

• Family: Rhabdoviridae, genus Lyssavirus
• Bullet-shaped, enveloped, negative-sense ssRNA virus

1. Inoculation via saliva (animal bite/scratch, rarely mucosal exposure)
2. Local replication in muscle
3. Entry into peripheral nerves (nicotinic acetylcholine receptor and others implicated)
4. Retrograde axonal transport to CNS
5. Encephalitis, then centrifugal spread (including salivary glands)

• Incubation: usually 1-3 months (variable)
• Prodrome: fever, malaise, paresthesia/pain at bite site (classic clue)
• Acute neurologic phase:
  • Furious rabies: agitation, hydrophobia, aerophobia, autonomic instability
  • Paralytic rabies: ascending weakness/flaccid paralysis
• Coma and death if untreated before symptom onset

• Clinical suspicion + exposure history is critical
• Confirmatory tests may include RT-PCR from saliva, skin biopsy immunofluorescence, CSF/serology (context dependent)

• Once symptomatic, disease is almost always fatal; care is largely supportive

• Immediate wound washing (soap/water, copious irrigation)
• Post-exposure prophylaxis (PEP) for unvaccinated:
  • Rabies vaccine series
  • Rabies immune globulin infiltrated around wound + remaining dose IM
• Previously vaccinated: vaccine boosters only (no RIG)
• Pre-exposure prophylaxis for high-risk groups (veterinarians, lab workers, certain travelers)

Quick comparison table