Picornaviridae – RNA Viruses, Pathogens and Diseases
Picornaviridae is a family of small RNA viruses that includes well-known pathogens such as poliovirus, rhinovirus, and enteroviruses, causing diseases of the respiratory tract, gastrointestinal system, and nervous system.
Wissenswertes über "Picornaviridae"
Picornaviridae is a family of small RNA viruses that includes well-known pathogens such as poliovirus, rhinovirus, and enteroviruses, causing diseases of the respiratory tract, gastrointestinal system, and nervous system.
What is Picornaviridae?
Picornaviridae is a large family of small, non-enveloped RNA viruses. The name is derived from the Italian word pico (small) and the abbreviation RNA. This virus family includes numerous medically significant pathogens capable of causing a wide range of diseases in humans and animals. Well-known genera include Enterovirus (e.g., poliovirus, coxsackievirus), Rhinovirus (the most common cause of the common cold), and Hepatovirus (hepatitis A virus).
Structure and Properties
Picornaviruses are very small (approximately 27–30 nm) and possess a single-stranded RNA genome with positive polarity (plus-strand RNA). They lack a lipid envelope, which makes them more resistant to detergents and desiccation. The capsid (protein shell) is arranged in an icosahedral structure that protects the genetic material.
- Genome size: approximately 7,000–8,500 nucleotides
- Non-enveloped (no lipid membrane)
- Icosahedral capsid
- Plus-strand RNA genome
Classification and Key Genera
The family Picornaviridae is divided into numerous genera. Those with the greatest medical relevance include:
- Enterovirus: Includes polioviruses (causative agents of poliomyelitis), coxsackieviruses (e.g., hand, foot, and mouth disease), echoviruses, and Enterovirus D68 (respiratory illness).
- Rhinovirus: The most frequent cause of the common cold in humans; more than 100 serotypes have been identified.
- Hepatovirus: The hepatitis A virus causes acute liver inflammation, typically transmitted through contaminated water or food.
- Parechovirus: Can cause severe systemic infections in infants and young children.
- Aphthovirus: Causative agent of foot-and-mouth disease in livestock.
Routes of Transmission
The transmission of picornaviruses varies depending on the genus:
- Fecal-oral route: The primary transmission pathway for enteroviruses and hepatitis A virus, typically through contaminated water or food.
- Droplet transmission: Rhinoviruses are mainly spread through respiratory droplets and direct contact with infected secretions.
- Contact transmission: Direct contact with infected individuals or contaminated surfaces.
Associated Diseases
Picornaviruses are responsible for a broad spectrum of illnesses:
- Common cold and rhinitis (rhinoviruses)
- Poliomyelitis (polioviruses)
- Hand, foot, and mouth disease (coxsackieviruses)
- Herpangina (coxsackieviruses)
- Aseptic meningitis and encephalitis (enteroviruses)
- Hepatitis A (hepatitis A virus)
- Myocarditis (inflammation of the heart muscle) caused by coxsackieviruses
- Severe respiratory infections due to Enterovirus D68
Diagnosis
Diagnosis of picornavirus infections relies on several laboratory methods:
- PCR (Polymerase Chain Reaction): The gold standard for direct pathogen detection in stool, throat swab, blood, or cerebrospinal fluid samples.
- Viral culture: Propagation in cell cultures; less commonly used in modern diagnostic settings.
- Serology: Detection of specific antibodies (e.g., for hepatitis A).
Treatment and Prevention
For most picornavirus infections, no specific antiviral therapies are available. Treatment is primarily supportive:
- Adequate fluid intake and rest
- Antipyretic medications as needed
- Intensive care measures in severe cases (e.g., respiratory support in poliomyelitis)
Preventive vaccines are available for some picornaviruses:
- Polio vaccine: Highly effective protection through the inactivated polio vaccine (IPV) or oral polio vaccine (OPV); the WHO aims for global eradication of poliomyelitis.
- Hepatitis A vaccine: An inactivated vaccine with excellent efficacy, recommended for at-risk groups and travelers.
General hygiene measures such as regular handwashing, access to safe drinking water, and safe food preparation are essential for preventing fecal-orally transmitted picornaviruses.
References
- World Health Organization (WHO): Poliomyelitis Fact Sheet. https://www.who.int/news-room/fact-sheets/detail/poliomyelitis (2023)
- Flint SJ, Racaniello VR, Skalka AM et al. - Principles of Virology, 4th Edition. ASM Press, Washington D.C. (2015)
- Knipe DM, Howley PM (eds.) - Fields Virology, 7th Edition. Lippincott Williams and Wilkins, Philadelphia (2021)
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Related search terms: Picornaviridae + Picornavirus + Picornaviruses