8 topics with a brief review: definitions, key facts, and classroom questions.
In this section, we examine the family Orthomyxoviridae, the primary and most dangerous representative of which is the influenza virus. You will systematically study its complex structure and replication cycle, epidemiology, and all stages of infection development: from pathogenesis and clinical manifestations to microbiological diagnostic methods, treatment, and specific prevention.
Special attention in classes and exams is paid to the antigenic structure of the virus (surface glycoproteins — hemagglutinin and neuraminidase) and its unique mechanisms of variability: antigenic drift and shift. These very processes explain the cause of regular seasonal epidemics, sudden pandemics, and the need to annually update vaccine compositions. A clear understanding of these mechanisms is your key to successfully passing the module.
Which genera of orthomyxoviruses cause disease in humans?
Three genera are pathogenic to humans: Influenzavirus A, Influenzavirus B, and Influenzavirus C.
Why does the influenza virus exhibit such high variability?
The viral genome is not a single molecule, but consists of 7 or 8 separate negative-sense RNA segments. This fragmented structure strongly predisposes to genetic recombination: if two different strains enter the same cell, they can exchange entire segments, generating a fundamentally new viral subtype.
Where exactly does transcription of the influenza virus genome take place, and why is this important?
Transcription takes place in the nucleus of the infected cell. This is a unique feature of the influenza virus compared to many other viruses whose life cycle occurs in the cytoplasm.
Which antigens determine the type of influenza virus (A, B, or C)?
The viral type depends on internal genus-specific antigens — nucleoprotein (NP) and matrix proteins (M proteins).
Can you catch the flu from a doorknob?
Yes, this is possible. An additional route of transmission is contact: the virus reaches the nasal mucosa or conjunctiva via contaminated hands after touching objects.
Which bacteria most commonly cause secondary pneumonia in influenza?
Superinfection is most commonly associated with S. pneumoniae (pneumococcus) or S. aureus (golden staphylococcus).
Study the full topic in the «Microbiology» course
This is a summary. The course covers everything tested in classes and exams.
4,383 pages of study guides across all topics
Assignments and quizzes after every topic — just like in a colloquium