Respiratory viruses Flashcards
Describe the pathogenesis of most respiratory viral infections.
What symptoms do they usually cause?
Viruses implant and replicate in the upper respiratory tract. They may spread to the lower tract.
Pneumonia, bronchitis/broncholitis, croup, pharyngitis, rhinitis.
Orthomyxovirus
What types and subtypes are there? What is the basis of this classification?
What is antigenic shift?
What is antigenic drift?
Orthomyxovirus
A/B/C, of which A has subtypes based on hemaglutinin and neuraminidase. Types are based on matrix/NP.
Reassortment of genes between a human and animal strain (often occurs in pigs).
Minor variations resulting from mutations over time.
Orthomyxovirus
Describe its pathogenesis.
Distinguish between acute infection in adults and children.
What are some possible complications of influenza virus infection?
Orthomyxovirus
The virus infects the upper RT ciliated epithelium. Cell destruction results from viral replication and CTL activation.
Infection in children is more severe, including otitis media, croup, myositis, GI symptoms and more severe fever.
The disease can facilitate a secondary bacterial pneumonia, muscle/heart involvement, and cause neurologic syndromes like GBS and encephalitis.
Orthomyxovirus
How is influenza diagnosed?
Describe current vaccines for influenza.
What chemical treatments are used to treat flu?
Orthomyxovirus
Antigen capture, agglutination assays, immunofluorescent microscopy.
Typical seasonal flu vaccines are trivalent and can be administered as a formalin-inactivated injection or a live-attenuated intranasal.
Amantadine/Rimantadine (blocks M2), Ribavirin (blocks RNA synthesis), Zanamivir/Oseltamivir (block NA).
Rhinovirus
What type of virus is it?
What symptoms does it cause, and how?
How is it treated?
Rhinovirus
A picornavirus.
Headache, cough, runny nose, sore throat; all due to inflammatory response.
There is no way to prevent or cure it. Some experimental treatments include protease inhibitors (ruprintrivir) and Pleconaril (block uncoating).
Coronaviruses
What symptoms does it cause?
Describe SARS.
Describe MERS.
Coronaviruses
It is the second-leading cause of the common cold–runny nose, sore throat, etc etc.
Originated from bats, spread by face-to-face contact but not all that contagious. Disappeared in 2003.
Affects people with underlying health issues. Not very contagious, but nosocomial infections identified. Ongoing.
Paramyxoviruses
Name some examples.
What proteins do they all have in common?
Paramyxoviruses
Measles, Parainfluenza, Mumps, RSV, hMPV, Hendra/Nipah.
A fusion protein (F), HA/NA, NA1/NS2 (modulate immune response), RNP for replication (one molecule).
Parainfluenza Virus
What do they cause, and who do they affect?
Distinguish between the four different types.
Parainfluenza
Can cause upper and lower RTI in the young/old/immunocompromised.
HPIV1/2 infect later in life and can cause croup (vaccines in Phase I). HPIV3 resembles RSV (vaccines passed Phase I). HPIV4 causes asymptomatic disease.
Respiratory Syncytial Viruses
What do they cause, and who do they affect?
Describe the pathogenesis.
Respiratory Syncytial Virus
Leading cause of fatal respiratory infections of young children. May also affect elderly.
Infect the respiratory tract, spread to lower airways (no viremia). Pneumonia due to syncytia formation, bronchiolitis from host immune response.
Respiratory Syncytial Viruses
Describe the host responses to RSV.
How is it treated?
Respiratory Syncytial Viruses
There may be a Th1 or Th2 response (former in adults, latter in children). It appears as if the Th1 response is preferable to the Th2 response…
Treatment is mostly supportive, though ribavirin or Ig can be administered. There is no vaccine, currently.
Human Metapneumovirus (hMPV)
What do they cause, and who do they affect?
How is it treated?
Human Metapneumovirus (hMPV)
Causes illness similar to RSV, affecting the young/old/immunocompromised but healthy adults as well! (especially winter season)
Same as RSV; supportive, or give ribavirin/IGs.
Hendra/Nipah
What is remarkable about these paramyxoviridae?
Hendra/Nipah
They have high mortality rates–seem to come from bats, like SARS.
Adenovirus
What do they cause, and who do they affect?
How does adenovirus spread from the respiratory tract or GI tract?
Is there a vaccine?
Adenovirus
Can cause wide spectrum: infections of respiratory tract, conjunctiva, GI tract, and urinary tract. Infections are more serious in immunocompromised patients.
Via the lymphatics (viremia). Note that it stays dormant in tonsils/adenoids.
Yes, but it is only typically administered to military servicepeople.
