Micro 46: Picornaviruses

This episode explores the picornaviruses, a large family of small, non-enveloped, positive-sense single-stranded RNA viruses. Drawing from Murray’s Chapter 46, it examines how genomic efficiency enables extensive clinical diversity.The family includes:* Enteroviruses (poliovirus, coxsackieviruses, echoviruses)* Rhinoviruses* Hepatitis A virusThe replication strategy is direct and efficient: the positive-sense RNA genome functions immediately as mRNA upon entry into the cytoplasm. Translation produces a single polyprotein that is cleaved into functional viral proteins.Clinically, picornaviruses demonstrate broad tropism:* Respiratory infection (rhinovirus - common cold)* Neurologic disease (poliovirus)* Myocarditis (coxsackievirus)* Gastrointestinal illness* Acute hepatitis (HAV)Conceptually, these viruses illustrate that small genome size does not limit clinical impact. Environmental resilience due to lack of envelope enhances transmission, particularly via the faecal–oral route.Key Takeaways* Picornaviruses are small, non-enveloped positive-sense RNA viruses* Genome acts directly as mRNA* Include enteroviruses, rhinoviruses, and HAV* Broad clinical spectrum* Transmission often faecal–oral or respiratory This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe