Microbiology
Summary
The Picornaviridae family comprises a diverse group of positive-sense, naked RNA viruses, which includes several notable members such as hepatitis A virus, poliovirus, coxsackievirus A and B, echovirus, and rhinovirus. Transmission of hepatitis A virus, poliovirus, coxsackievirus A and B, and echovirus occurs fecal-orally, while rhinovirus is transmitted through respiratory droplets.
Hepatitis A virus infection is associated with a range of symptoms, including hepatitis, gastroenteritis,, hepatomegaly, and less frequently, splenomegaly. Among the enteroviruses, including poliovirus, coxsackievirus A and B, and echovirus, aseptic meningitis is a well-recognized outcome. This condition is more commonly observed in children. Rhinovirus, specifically targeting the upper respiratory tract, is a common culprit behind the common cold and other upper respiratory infections.
Lesson Outline
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FAQs
Picornaviridae is a family of RNA viruses characterized by their small, non-enveloped viral particles, icosahedral capsids, and a positive-sense RNA genome. They are significant in viral studies due to their wide range of hosts and diseases they cause, including poliomyelitis, hepatitis A, and the common cold. Understanding their replication mechanisms and transmission modes can contribute to better prevention and treatment approaches for viral diseases.
As a positive-sense RNA virus, the Picornaviridae viral RNA genome can be directly translated into protein by host cells once inside. This characteristic simplifies and speeds up the viral replication process, investing in efficient and rapid pathogenesis. The viral proteases cleave the resultant polyprotein to form mature viral proteins, culminating in the production of new virus particles.
Meningitis caused by picornaviruses often originates from Enteroviruses (a genus within Picornaviridae). The three main picornaviruses associated with viral meningitis are coxsackievirus, echovirus, and poliovirus. These can spread to the nervous system and cause inflammation of the meninges, leading to symptoms like headaches, fever, and stiff neck.
Rhinovirus, compared to other Picornaviridae members like hepatitis A virus or poliovirus, predominantly causes upper respiratory tract infections or common colds and is typically transmitted via the respiratory route, rather than fecal-oral transmission. Furthermore, rhinovirus has a preference for cooler temperatures, making the nasal cavity an optimal site for replication.
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