Respiratory Viruses I, II, & III Flashcards
In general, symptoms from a viral infection depend on ______________.
where the virus has infected (e.g., nasopharynx, upper airway) and not on the specific virus itself
Name the viral syndrome based on where it infects.
Rhinitis (nasal turbinate) Pharyngitis Laryngitis Tracheitis Bronchitis Bronchiolitis Bronchopneumonia
What viruses most commonly infect the respiratory tract?
Influenza Parainfluenza Coronavirus Rhinovirus Adenovirus Respiratory syncytial virus Human metapneumovirus
Some viruses prefer different ______________.
temperatures; Rhinovirus, for instance, prefers to replicate at 33º (which is the temperature of the nasopharynx)
Describe the three patterns of viral replication.
- Acute infection with replication confined to respiratory mucosal surface: RSV, Coronovirus, Picornavirus, Parainfluenza virus, and Othomyxovirus
- Persistent replication confined to mucosal surface: EBV, HPV, and adenovirus
- Primary infection followed by systemic infection: VZV, HHV6, Poxvirus, Paramyxovirus, and Rubella
What family is influenzavirus in?
Orthomyxoviridae
The only RNA virus that replicates in the nucleus is ______________.
Influenzavirus
Give a rundown on Influenzavirus.
- ssRNA
- Negative sense
- Enveloped
- Segmented
The paramyxoviridae family includes ______________.
- Paramyxovirus: Mumps and Parainfluenza
- Morbillivirus: Measles
- Pneumovirus: RSV
- Henipavirus: Hendra and Nipah
What do the H and N stand for in influenza nomenclature?
Envelope glycoproteins:
•H: hemagglutinin
•N: neuraminidase
What organisms can influenza A, B, and C infect?
A: humans and many other animals
B: humans
C: humans
Influenza vaccines target which strains of influenza?
A and B
The surface proteins of __________ are the most variable.
influenza strain A
Very few people infected with ____________ are asymptomatic.
influenza
Research shows that about __________ people are infected per case of influenza.
three to nine
True or false: in rare cases, influenza can develop systemic viremia.
False. Influenza is confined to the respiratory mucosa.
It is estimated that about ___________ influenza deaths per year could be prevented by better vaccination rates.
20,000
What’s the difference between antigenic drift and antigenic shift?
•Antigenic drift is the accumulation of point mutations that leads to immune escape.
–Occurs in all strains of influenza
•Antigenic shift is the sudden accumulation of new surface proteins from other virions, such as in a person who got infected with two strains of A.
– Occurs only in strain A because that is the only one that can move from animals to humans
(“Shift is Sudden. DRIft occurs DRIp by DRIp.”)
Amantadine blocks ____________.
M2
Why do paramyxoviruses have less variation than orthomyxoviruses?
Paramyxoviruses are not segmented!
Where do paramyxoviruses replicate?
In the cytoplasm (unlike orthomyxoviruses)
Has there ever been a vaccine for RSV?
Yes. In the 1960s, there was an RSV vaccine but it was shown to increase mortality via an eosinophil-mediated reaction.
In the absence of vaccination, __________ infection is almost universal.
measles
Worldwide, measles kills greater than ___________ children per year.
one million
The mortality of measles is about ____________ in developing countries.
5-10%
Most measles deaths are due to ___________________.
secondary infections from a poorly understood mechanism in which measles suppresses the immune system
How is measles transmitted?
Respiratory
Note: measles is not transmitted by the rash that it produces.
Where does measles replicate?
Nasopharynx and regional lymph nodes
What are Koplik’s spots?
Characteristic of measles, Koplik’s spots are erythematous macular spots in the mouth with white centers.
Measles in pregnancy can cause __________.
premature labor, spontaneous abortion, and low birthweight infants
_______________ are the only reservoir for mumps.
Humans
Mumps is transmitted by _____________.
respiratory secretions (the rash is not infectious)
Where does mumps replicate?
Respiratory epithelium, lymph nodes, and eventually the blood
Human metapneumovirus is in the _____________ family.
paramyxovirus (in the pneumoviridae)
Give a rundown on HPMV.
- Negative-sense ssRNA
- Non-segmented
- Four subtypes
- Discovered in 2001
- Causes both URT and LRT infections
Give a rundown on Adenovirus.
- Isolated from the adenoidal tissue of children with febrile illness
- 47 serotypes that can infect humans (53 more that )
- dsDNA virus
- Icosahedral
- Non-enveloped
Most Adenovirus infections present with __________.
nothing (i.e., most people are asymptomatic)
What can Adenovirus cause?
- Myocarditis
- Hemorrhagic cystitis
- Conjunctivitis
A vaccine was recently approved for _____________.
four strains of Adenovirus
__________ is the most common cause of URTs.
Rhinovirus
______________ are the largest positive-sense RNA virus.
Coronavirus
Where does the name Coronavirus come from?
The large glycoprotein spikes make the virus look like a crown on transmission electron microscope.
Coronaviruses are _____________ and thus less stable in the environment.
enveloped
What kind of virus causes SARS and MERS?
Coronavirus
Which three viruses cause the most respiratory infections?
Rhinovirus (50%), Coronavirus (15%), and Influenza (15%)
Measles mortality is highest in ____________.
girls
The incubation period for Measles is roughly _______________.
6 days
CMV prefers the __________ respiratory tract.
lower
There are typically _____________ infections per clinical case of influenza.
3-9
What two Adenovirus diseases are not in the Sketchy scene?
Respiratory infections and gastroenteritis
