Myxoviruses and Coronaviruses Flashcards
What are myxoviruses and what is the difference between ortho- and paramyxoviruses?
Myxoviruses have affinity for mucus (Greek myxa means mucous). Ortho are the originally-described myxoviruses, para are similar but not identical to the orthos
List clinically significant orthomyxoviurses and paramyxoviruses (6 total)
Ortho - influenza, para - parainfluenza, mumps, pneumovirus (RSV), human metapneumovirus, and nipah virus (also measles)
What type of genome do orthomyxoviruses have and where do they replicate?
Segmented, Negative sense RNA, replicate in nucleus
Influenza is type as A, B, or C. What two designations is an influenza type A virus given and what are the possible designations for each?
Hemagglutinin (HA) and Neuraminidase (NA). H1 through H13 and N1 through N9 (e.g. H1N1)
What influenza strain appeared in Hong Kong in 1997, why was it surprising, and what is the strains current status?
H5N1, previously thought humans only got H1 through 3 (and N1 and N2), currently circulating through SE Asia
Which types of influenza (A, B, or C) are most responsible for human disease?
A and B
How many segments does each influenza type (A, B, and C) have?
A - 8, B - 8, C - 7
Is influenza nucleocapsid helical or icosahedral?
Helical
What does the influenza HA protein do and what must be done to it for the virus to be infectious?
It helps virus attach to and penetrate cell. Must be cleaved into HA1 and HA2 for viral infectivity
What is the difference between antigenic drift and antigenic shift?
Drift implies small changes (e.g. point mutations), while shift suggests major changes (e.g. HA and NA reassortment in pigs)
Drift in which influenza protein tends to have more clinical impact?
HA
How many HA epitopes typically have to undergo antigenic drift for it to be clinically significant?
Two or more
What form does influenza virus tend to take outside the body?
Small particle aerosol (can survive for long periods of time)
Within 24 hours of onset of influenza symptoms, what is seen histologically?
Destruction of ciliated epithelial cells and mucous-secreting cells. Then edema, hyperemia, PMN and mononuclear cell infiltration
What is the incubation period of influenza?
1 to 5 days
Typical symptoms of uncomplicated adult influenza infection
Tracheobronchitis, headache, fever, chills, dry cough, myalgia, malaise, anorexia (chest x-ray usually normal)
What additional influenza symptoms are often seen in pediatric infections?
High fever, GI issues, pulmonary issues, ear infections, enlarged cervical lymph nodes
Reyes syndrome is associated with salicylate administration during influenza in children. Which type of influenza is most commonly associated with Reyes?
Influenza B infection
Amantadine and Rimantadine are used as antivirals. How do they work?
Target M2 protein and viral uncoating
How does Tamiflu work against influenza virus?
It is a neuraminidase (NA) inhibitor. It affects viral assembly and release
What is FLU-MIST?
A new, live, cold-adapted, temperature sensitive, attenuated influenza vaccine. Might work better than traditional deactivated influenza vaccine
The term Avian flu is usually used to describe influenza viruses of what HA and NA numbers?
H5N1
Why is the recent H1N1 called a quadruple reassortant virus?
It has genes from European and Asian pig strains (2 genes) as well genes from avian and human strains
The current flu vaccine protects against what flu strains?
H3N2, H1N1, and an Influenza B strain
