AuCoin: Influenza and viral pneumonia Flashcards
inflammation of the lungs caused by infection with a virus or bacteria
pneumonia
Which portion of the pulmonary parenchyma is primarily affected by pneumonia?
alveoli
viral pneumonia more likely to occur in these populations due to a naïve or weakened immune system, respectively
young children
older adults
Three most common causes of viral pneumonia
Influenza A and B
RSV
Human parainfluenza virus
What are some defense mechanisms that we have to protect from pneumonia?
epiglottis and cough reflex
ciliated epithelium to propel mucous toward the mouth
cell mediated immunity in the lung
How is the influenza virus transmitted? Which strains of this virus cause outbreaks? What are two methods in which this virus spreads and causes epidemics?
respiratory droplets
pandemics caused by influenza A and B
antigenic shift and antigenic drift make it hard to contain/prevent this virus from spreading
**mutability and a high frequency of genetic reassortment make controlling infection challenging
These folks are at high risk for influenza virus infection
the elderly and those with cardiac or pulmonary disease
What can complicate influenza?
pneumonia caused by Staph aureus
Immunity to influenza depends on (blank) in the respiratory tract
secretory IgA targeting HA
How to treat influenza? How to prevent it?
Tamiflu or Relenza;
prevent with flu vaccine (which has A and B strains, and is reformulated yearly)
Which strain of influenza causes the most disease?
A
**influenza A is antigenically variable, less changes occur with B and C
When does the flu virus circulate?
fall and early spring
The flu virus binds to host cells via the (blank) receptor, and is endocytosed. The genome is transported to the (blank) where replication and transcription occur. Then the viral mRNA are transported back to the (blank) for translation. Assembly and budding of the virus occurs at the plasma membrane.
sialic acid; nucleus; cytoplasm
Why is influenza unusual among the RNA viruses?!
RNA transcription occurs in the nucleus!
In the flu virus, the virus encoded RNA polymerase is composed of three viral proteins (P proteins) are responsible for transcription
the polymerase will produce (blank) mRNA from the (-) sense RNA genome
the (blank) mRNA will be translated into viral proteins and also used as a template to produce viral (-) sense RNA genomes
+ sense
+ sense
In the flu virus, the nucleoprotein associated with the viral RNA to form a (blank). Three other encoded proteins (PA, PB1, PB2) are bound to the NP and are responsible for (blank)
ribonucleoprotein;
RNA transcription and replication
(blank) forms a shell below the viral membrane important in particle assembly
(blank) surrounds the viral particle derived from the plasma membrane of the host cell
matrix protein (M1); lipid envelop
These two surface glycoproteins are important antigens that determine antigenic variation of influenza viruses
hemagglutinin (HA)
neuraminidase (NA)
T/F: two distinct influenza viruses cannot infect a single host cell
false; they can!
When two infleunza RNA genomes are shuffled inside the host cell, re-assortment occurs. Why is this a problem?
this shuffling creates a change in the viral surface antigens –> explains the challenge in producing only one influenza vaccine
What is used to divide influenza viruses into types A, B and C?
antigenic differences between nucleocapsid (NP) and matrix (M) proteins
What is used to subtype the virus?
ex: HA1-HA15
antigenic variation among surface glycoproteins, HA and NA
ex: 15 subtypes of HA (HA1 – HA15) and nine sutypes of NA (N1-N9) in many different combinations isolated in birds, animals or humans
(blank) is the major antigen against with neutralizing (protective) antibodies are directed
HA
(blank) functions at the end of the viral replication cycle and facilitates release of virus particles from infected cell surface during the budding process
NA
minor antigenic changes are antigenic (blank), major changes in HA and NA are termed antigenic (blank) (new subtypes)
drift; shift
due to the accumulation of point mutations in the gene and sequence changes can alter antigenic sites on the glycoproteins
antigenic drift
reflects drastic changes in the sequence of the viral glycoproteins
genetic reassortment between human and avian influenza viruses
antigenic shift
influenza virus spreads from person to person by (blank) or by contact with contaminated surfaces
cells of the (blank) are infected, these cells are killed and the virus spreads to many other cells
the incubation period is 1 to 4 days
(blank) is detectable in respiratory secretions ~1 day post infection
(blank) and cell-mediated immunity is detectable in 1-2 weeks
cellular destruction is widespread and therefore resistance to secondary bacterial infections is common (staph, strep, and Haemophilus influenzae)
respiratory droplets;
respiratory epithelium;
interferon;
antibody
What is the recommendation for the flu vaccine?
Routine annual influenza vaccination is recommended for all persons aged 6+ months
Three kinds of flu viruses commonly circulate among people today:
A H1N1
A H3N2
B
most common cause of pneumonia and bronchiolitis in infants
Neonates, premature infants, and infants with cardiopulmonary disease susceptible
Transmitted via respiratory droplets
RSV
What does RSV cause in adults? In the elderly? In infants?
adult: common cold, bronchitis
elderly: pneumonia
infants: cough, wheezing, pneumonia, bronchiolitis
How to treat severely ill patients with RSV?
Ribavirin
Passive immunity with antibody is an option, too
**control outbreaks via hand washing and glove use
What are the surface spikes on RSV?
they are fusion proteins, which cause cells to fuse and form multinucleated cells (syncytia) –> gives rise to the name respiratory syncytial virus
**the spikes are not hemagglutinins and neuraminidases like in the flu virus
A 6-week-old infant is brought to the pediatric clinic in respiratory distress. Physical examination is significant for diffuse expiratory wheezing and mild cyanosis. The chest X-ray is suggestive of bilateral pneumonia. The infant is admitted to the intensive care unit. Nasopharyngeal swab and nasopharyngeal washing are sent for culture and direct examination.
RSV
PIVs cause croup, laryngitis, bronchiolitis, and pneumonia in children
Cause a disease resembling the common cold in adults
These viruses are transmitted via respiratory droplets
Parainfluenza virus
characterized by a barking cough and hoarseness
Also cause a variety of respiratory diseases such as the common cold, pharyngitis, laryngitis, otitis media, bronchitis, and pneumonia
croup
main cause of croup in children younger than 5 years old
parainfluenza virus 1 and 2
What are the surface spikes on the parainfluenza virus?
hemagglutinin (HA)
neuraminidase (NA)
and fusion proteins
fusion proteins mediate the formation of multinucleated giant cells
A 2-year-old child is brought to the emergency department by worried parents because of a barking cough and inspiratory stridor that got worse at night. The present illness began 2 days earlier with a fever, sore throat, rhinorrhea, and mild cough. Finding on examination include a temperature of 102oF, tachypnea, wheezing, and respiratory distress.
parainfluenza virus
A 70-year-old women with a history of congestive heart failure is seen in January by her primary care physician with an abrupt onset of fever, cough, and myalgia that requires hospitalization. Two days later, she experiences increasing cough and shortness of breath. Chest X-ray reveals lung infiltrates.
influenza virus
