Influenza Flashcards
T or F: Influenza causes an acute febrile respiratory disease
TRUE, doesn’t cause the so called “stomach flu”
What is the genome of influenza?
made of 8 different pieces of (-)ssRNA which encode several different viral proteins
What surrounds the genome of influenza?
core is covered by lipid envelope, with a lining of matrix protein on the inner side of the envelope.
What are the 2 most characterized proteins of influenza?
hemagglutinin (H) and neuraminidase (N) glycoproteins. Different types of these are numbered (that how you get H1N1 or H3N2) and are on viral coat
How many types of influenza virus are there?
- Type A, B, and C. Type C cause milk or insignificant illness
What is significant about Type A strains?
cause both epidemics and pandemics. Can also infect other animals (horses, seals, swine, and birds)
How does influenza nomenclature work?
Virus type/Geographic origin/Stain number/ Year of isolation (Virus subtype). Example A/Moscow/21/99 (H3N2)
What is antigenic drift?
gradual changes in the virus that occurs through a slow series of mutations, substitutions, or deletions in amino acids constituting the H and N surface antigens
What causes antigenic drift?
point mutations in response to antibodies after virus strain is established in humans.
What is antigenic shift?
occurs when a type A influenza with a novel hemagglutinin or neuraminidase gene segment is introduced into humans
How does antigenic shift occur?
Gene reassortment can occur when 2 or more influenza viruses infect a single human or animal
Why does antigenic shift occur?
segmented genome means gene segments can be swapped between strains
What makes pigs so special?
That can be infected by strains from 3 different species: birds, pigs, and humans. This makes pigs great “mixing vessels” for presenting novel influenza to a new species.
Where is 2009 H1N1 come from?
multiple reassortments of avian, human, and swine flu in pigs.
T or F: Type A and B can go through antigenic shift
FALSE, only Type A can because B only infects humans
How is Influenza transmitted?
Respiratory route. Droplet and small particle aerosols. Also can live on fomites for hours to days. Lives on hands for 5 min
How does influenza infection present?
acute onset of fever, chills, myalgias, headache, and cough
T or F: neonates and infacts are infected much worse with influenza
TRUE, can present with decreased eating, mottling, apnea, GI symptoms, fever, anorexia, fevrile URI, acute laryngotracheobronchitis, bronchititis, and febriel convulsions
Treatment of influenza with drugs
matrix protein inhibitors (only if susceptible), and euraminidase inhibitors (only if susceptible)
What are the 2 types of licensed seasonal influenza vaccines?
1) Inactivated influenza vaccine (injectable, killed vaccine) 2) Live attenuated influenza vaccine (intranasally)
What can you say about the influenza stains in both vaccines?
They both have the same 3 strains of influenza, and the quadrivalent vaccine contains the same 2nd B strain. Reformulated annually to provide best protection for anticipated strains.
Whats a “well-matched year”?
When the vaccine strain are guessed correctly and provide protection
Whats a “mismatched year”
When the vaccine strain are guessed incorrectly and don’t do shit.
Efficacy of TIV/IIV (inactivated vaccine)
70% effecting in preventing influenza. Declines in elderly (30-40%) a 50-60% hospitalization and 80% mortality reduction is seen in elderly.
