HRR: respiratory viruses Flashcards
How can we determine if a virus is active or inactive?
Introduce them to an appropriate host system and look for replication
What are two major structures of viruses?
Naked and enveloped
Describe a naked virus structure.
A protein capsid with genomic material inside
How are naked viruses released?
Via lysis
Describe an enveloped virus structure.
A protein capsid with genomic material inside surrounded by a lipid envelope with embedded proteins
How are enveloped viruses released?
They bud from the plasma membrane or into vesicles that fuse with the plasma membrane
How do enveloped viruses get their membrane?
They steal it from the host via budding
Which virus structure is resistant to inactivation via ethanol?
Naked
Which virus structure is vulnerable to inactivation via ethanol?
Enveloped
What are two main capsid shapes?
Helical and spherical
Which nucleic acid polymerase enzymes are only found in viruses?
RNA-dependent RNA polymerases and RNA-dependent DNA polymerases (reverse transcriptase); they’re used as drug targets
What virus genomes replicate in the nucleus?
ssDNA, dsDNA, retrovirus (RNA)
What virus genomes replicate in the cytoplasm?
dsRNA, -ssRNA, +ssRNA
What virus genome types establish latency/lifelong infection?
DNA and retrovirus RNA
What are nuclear inclusions?
Formed by DNA viruses in cells
Which virus families cause respiratory infections?
Picornaviruses, bocaviruses, coronaviruses, adenoviruses, ortho, and paramyxoviruses
All respiratory viruses are…
Endemic
Most bacterial pneumonias are preceded by…
A viral respiratory infection
Rhinovirus: season and high-risk group?
Year round, NA
Enterovirus: season and high-risk group?
Summer, children
Bocavirus: season and high-risk group?
Unknown, children
RSV: season and high-risk group?
Winter; children, elderly, HSCT recipients
Coronavirus: season and high-risk group?
Year-round, varies
Adenovirus: season and high-risk group?
Year-round, varies
Parainfluenza virus: season and high-risk group?
Type 1 in fall, type 3 in spring; children and HSCT recipients
Influenza: season and high-risk group?
Winter, varies
What are the two categories of picornavirus?
Rhinoviruses and enteroviruses
What is the basic structure of picornavirus?
Small icosahedral, naked, +strand RNA virus
What is the difference between rhinovirus and enterovirus?
Rhinoviruses are acid-labile, meaning they do not survive contact with acid. If they’re swallowed, they’ll be killed in the stomach. Enteroviruses can survive the stomach and thus enter the bloodstream.
What is the main mode of transmission of picornavirus?
Transmission from surfaces
What are the human host cell receptors for HRV-A?
LDLR or ICAM-1
What are the human host cell receptors for HRV-B?
ICAM-1
What are the human host cell receptors for HRV-C?
CDHR3
What is the clinical presentation of picornaviruses?
Common cold symptoms, nasal congestion caused by bradykinin. Lower respiratory tract infection is rare.
Which virus is the most common cause of acute asthma episodes?
Rhinoviruses
Repeated ___ infections increase risk of developing asthma in genetically susceptible people.
HRV-C
How do we treat/prevent picornaviruses?
We don’t; no vaccine and no medications
What is the structure of bocaviruses?
Naked, isohedral, ssDNA genome