Influenza & Viral pneumonia Flashcards
What is pneumonia?
an inflammation of the lungs caused by infection with a virus or bacteria + immune response of body
mainly parenchyma, alveoli are affected
Which populations are most likely to experience viral pneumonia?
young children or older adults b/c of their weakened immune systems
also those with cardiac or pulmonary disease
What are typical symptoms of pneumonia?
cough
fever
chills
SOB
What are common causes of viral pneumonia?
Influenza Virus A & B
RSV
Human parainfluenza virus
Why is is RSV called respiratory syncytial virus?
b/c it forms a syncitia as cells fuse together. eventually, one cell has hundreds of nuclei.
What are some less common causes of viral pneumonia?
Adenoviruses
Rhinoviruses
Metapneumoviruses
SARS
What are disease causing viruses that can secondarily cause pneumonia?
Herpes simplex virus Varicella-zoster virus Measles Rubella Cytomegalovirus
What does human parainfluenza virus cause?
croup
Which of the viruses that we have talked about belong to the paramyxovirus family?
RSV
human parainfluenza virus
What are some pulmonary defense mechanisms that keep junk from getting into the lower airway?
cough reflex
epiglottis
Describe the defense mechanisms in the lower airway.
goblet cells are in the airway along w/ ciliated columnar respiratory epithelium.
goblet cells secrete mucus & the cilia beat it upwards to the mouth.
What is a defensive antibody in the airway?
IgA–mucosal immunity
Which category of viruses cause influenza?
Family of Orthomyxo, includes paramyxo.
These are enveloped neg strand RNA viruses.
How is the influenza virus transmitted? What are the different types? Which type is responsible for the most pandemics?
transmitted via resp droplets
Types A,B,C
Pandemics caused by A, B–>but mostly A.
What are 2 important things on the surface of the influenza A virus? How many subtypes of each?
Hemagluttinin HA: 16
(need for leaving the cell) NA: 9
What are the 2 ways that the influenza virus can change & therefore cause pandemics?
antigenic shift: reassortment of genome RNA when 2 different viruses infect the same cell.
antigenic drift: small mutations in genome RNA
What does HA do on the influenza virus?
agglutinates RBCs
sometimes a viral attachment protein.
What is the incubation period of the flu? After this period, which symptoms pop up?
24-48 hours fever myalgia headache sore throat cough
When do the symptoms of the flue subside?
in 4-7 days
but can be longer if pneumonia results.
For the flu….
what determines immunity? Treatment? Prevention?
Immunity-IgA that targets HA
Treatment-Tamiflu & Relenza
Prevention–vaccines for Influenza A & B
Which receptor does the influenza virus bind to in the lungs?
sialic acid receptor–found everywhere in the lungs
then receptor mediated endocytosis
What is the season for influenza?
fall & early spring
Describe the entire replication cycle for the influenza virus.
Receptor mediated endocytosis (sialic acid receptor)
Segmented ribonucleoproteins released into the cytoplasm
Genome transported to the nucleus
Replication and transcription
Viral mRNAs transported to the cytoplasm for translation
Early viral replication proteins transported back to the nucleus
Assembly and budding occurs at the plasma membrane
If a negative sense RNA strand is transacted into a lung epithelial cell what will happen?
It won’t infect unless it has with it an RNA-dependent RNA polymerase to make a positive sense strand. Then it can use the cell machinery to make the necessary proteins for infection.