Microbiology · MU Plovdiv

46. Poxviridae – the causative agent of smallpox. Adenoviridae. Rhabdoviridae – the causative agent of rabies. Rotaviridae.

Inside: 27 sections · 22 labelled pictures · 6 tables · 60 flashcards · 12 min

Topic 46 of 50 in the MU Plovdiv syllabus for Microbiology (Medicine, Years 2 and 3). The free AceMed note covers it in 24 sections, about 1,459 words (12 min of reading), with 60 flashcards.

In this note

  1. Family Reoviridae - Genus Rotavirus. Genus Norovirus.
  2. I. General Characteristics
  3. II. Morphology and Structure
  4. III. Rotavirus
  5. IV. Norovirus
  6. V. Summary Table – Rotavirus vs Norovirus
  7. Family Rhabdoviridae – Rabies Virus
  8. II. Structure and Genome
  9. III. Pathogenesis
  10. IV. Virulence Factors
  11. V. Clinical Features
  12. VI. Diagnosis
  13. VII. Treatment
  14. VIII. Prevention and Post-Exposure Prophylaxis (PEP)
  15. Family Adenoviridae | Genus Papillomavirus | Genus Polyomavirus
  16. I. Family Adenoviridae
  17. II. Genus Papillomavirus
  18. III. Genus Polyomavirus
  19. Family Poxviridae – Variola Virus (Smallpox Virus)
  20. II. Structure and Replication
  21. IV. Clinical Features – Smallpox (Variola major)
  22. V. Diagnosis
  23. VI. Prevention and Eradication
  24. VII. Immune Evasion

I. General Characteristics

  • Rotavirus (Reoviridae):
  • Non-enveloped, double-stranded segmented RNA virus.
  • Triple-layered icosahedral capsid.
  • Replicates in the cytoplasm.
  • Genome is 11 segments, allowing genetic reassortment.
  • Transmission: Fecal–oral route.
  • Major cause of severe diarrhea in infants and young children.
  • Norovirus (Caliciviridae):
  • Non-enveloped, single-stranded, positive-sense RNA virus.
  • Icosahedral capsid, very small (~27–35 nm).
  • Highly infectious and environmentally stable.
  • Transmission: Fecal–oral, aerosols from vomitus, contaminated food/water.
  • Major cause of adult viral gastroenteritis and outbreaks (e.g., cruise ships, schools).

III. Rotavirus

A. Virulence Factors

  • NSP4: acts as a viral enterotoxin → stimulates Cl⁻ secretion, inhibits Na⁺ absorption → watery diarrhea.
  • VP4 and VP7: outer capsid proteins responsible for attachment and neutralization.
  • Segmented genome: allows antigenic shift (reassortment).
  • Resistance to gastric acid → survives passage to intestines.

B. Pathogenesis

  • Infects and destroys mature enterocytes in small intestinal villi → malabsorption.
  • NSP4 induces secretory diarrhea via Ca²⁺-dependent signaling and enteric nervous system activation.
  • Leads to dehydration and electrolyte imbalance, especially dangerous in infants.

C. Clinical Features

  • Incubation: 1–3 days.
  • Symptoms:
  • Vomiting and watery diarrhea (5–7 days)
  • Low-grade fever
  • Dehydration (major risk)
  • Affects mainly children <5 years (peak at 6 months – 2 years).

D. Diagnosis

  • Enzyme immunoassay (EIA) for rotavirus antigen in stool.
  • RT-PCR or latex agglutination (less common in routine use).

E. Treatment and Prevention

  • Supportive care: oral rehydration, IV fluids if needed.
  • Vaccination:
  • Live attenuated oral vaccines:
  • Rotarix (monovalent)
  • RotaTeq (pentavalent)
  • Given in infancy (starting at 6–8 weeks of age).

Continue reading free

The whole note, all 24 sections, is free with an AceMed account, with its 60 flashcards. Premium adds flashcard recall, highlights and Ask AI.

Start freeAlready a member? Open the note