Picornaviruses (Enteroviruses, Poliovirus, Coxsackie, ECHO, Rhinoviruses, Hepatitis A)
6 topics with concise breakdowns: definitions, key facts, and class questions.
The family Picornaviridae ("small RNA viruses") is a massive group of pathogens causing a spectrum of diseases ranging from the common cold to severe paralysis and liver damage. Despite their tiny size, their clinical significance for future doctors is colossal.
In this section, we will analyze the general characteristics of the family and study its key representatives in detail. We will cover enteroviruses, including the formidable poliovirus, the multifaceted Coxsackie and ECHO viruses, and the hepatitis A pathogen. We will also examine rhinoviruses separately as the main culprits of seasonal rhinitis and acute respiratory viral infections (ARVI).
Classes and exams most frequently test the pathogenesis of poliomyelitis, the clinical differences between infections caused by Coxsackie viruses A and B, and the laboratory markers of hepatitis A. Pay special attention to specific prophylaxis: the administration schedules and differences between polio vaccines (live OPV and inactivated IPV) are an absolute hit on microbiology tests.
Because it is represented by plus-strand RNA, which immediately acts as messenger RNA (mRNA) upon entering the cell cytoplasm. Ribosomes can immediately begin reading information from it without prior transcription.
Why do enteroviruses not die when treated with alcohol?
They lack a lipid envelope (supercapsid). Because of this, alcohols, ether, and other fat solvents are ineffective against them.
Why does the poliovirus cause paralysis specifically?
The virus exhibits tropism for motor neurons located in the anterior horns of the spinal cord. The destruction of these cells leads to a loss of motor function and the development of flaccid paralysis.
What is the main microbiological difference between ECHO viruses and Coxsackie viruses?
ECHO group viruses are completely non-pathogenic to laboratory animals. Coxsackie viruses, in contrast, are pathogenic to newborn mice (suckling mice), which is used for their isolation.
Why can a person contract a rhinovirus infection multiple times in one season?
More than 100 serotypes of the virus circulate in nature. Following an infection, type-specific immunity develops, which does not protect against other variants.
To which family does the hepatitis A virus belong?
To the family Picornaviridae (genus Hepatovirus).
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