MLT GlobeVirology: Respiratory viruses
37 Virology MCQs on Respiratory viruses with answers and explanations.
Measles virus (genus Morbillivirus) belongs to which family?
Measles virus is an enveloped negative-sense RNA virus of family Paramyxoviridae. Rubella (Matonaviridae, formerly Togaviridae) is a different virus.
Which statement about mumps is correct?
Mumps may cause orchitis, oophoritis and pancreatitis besides parotitis. It has one serotype, grows in cell culture, and is prevented by live MMR vaccine.
Influenza viruses primarily infect and damage which body system?
Influenza haemagglutinin binds sialic-acid receptors on respiratory epithelium, causing tracheobronchitis and pneumonia. Heart involvement is an uncommon complication.
Rhinoviruses are acid-labile. Which specimen is therefore unsuitable for recovering them?
Rhinoviruses are destroyed by stomach acid and replicate only in the upper airway at about 33 °C, so they are not recovered from feces.
Rhinovirus often spreads when fingers contaminated with nasal secretions touch the eyes or nose. What is this route called?
Rhinoviruses survive for hours on skin and surfaces; hand contact followed by touching the nose or eyes is an efficient route, so hand hygiene is emphasised.
Amantadine inhibits which virus, though resistance now limits its clinical use?
Amantadine blocks the M2 ion channel of influenza A, preventing uncoating; influenza B lacks M2. Most circulating influenza A strains are now resistant.
A toddler has a barking cough and inspiratory stridor. Which paramyxovirus is the most common cause of this croup?
Human parainfluenza viruses, especially type 1, are the leading cause of croup (laryngotracheobronchitis). Parvovirus, not a paramyxovirus, causes fifth disease.
A young man with painful parotid swelling develops painful testicular swelling a week later. Which virus is responsible?
Orchitis occurs in about 20-30% of post-pubertal males with mumps; it is usually unilateral and rarely causes sterility.
Which virus is the leading cause of bronchiolitis and viral pneumonia in infants?
RSV causes most infant bronchiolitis and pneumonia, peaking in winter; it forms syncytia in culture and is diagnosed by antigen tests or PCR.
Why has no vaccine against the common cold been produced?
More than 150 rhinovirus types with little cross-protection make a practical vaccine very difficult; immunity after infection is type-specific.
Which vaccine type is most widely given by injection each year to protect against seasonal influenza?
Injectable inactivated split or subunit vaccines are updated annually for antigenic drift. Live attenuated influenza vaccine exists but is given intranasally.
The measles component of MMR vaccine is best described as which type?
MMR contains live attenuated measles, mumps and rubella viruses; it is contraindicated in pregnancy and severe immunodeficiency.
Besides influenza, which virus commonly causes acute respiratory disease, notably outbreaks among military recruits?
Adenoviruses (e.g. types 4 and 7) cause pharyngitis, pneumonia and acute respiratory disease in crowded settings like barracks.
Which virus-feature pairing is INCORRECT?
Antigenic shift (genome segment reassortment) occurs in influenza A, which has a segmented genome; mumps has one serotype and no shift.
Influenza vaccine must be updated every year. The main reason is that the virus:
Influenza is an orthomyxovirus with a segmented negative-sense ssRNA genome. Point mutations (drift) and reassortment (shift) of HA/NA mean yearly strain updates. Latency is a herpesvirus feature.
A child with fever, cough, conjunctivitis and bluish-white spots on the buccal mucosa before a rash is most likely infected with which paramyxovirus?
Koplik spots are an enanthem on the buccal mucosa that is pathognomonic of measles. They appear before the maculopapular rash.
Which specimen is generally preferred for detecting respiratory viruses such as SARS-CoV-2 or RSV by PCR?
Nasopharyngeal specimens have high viral loads, and flocked swabs release cells well into transport medium. Formalin and dry tubes damage viral nucleic acid and viability.
Influenza A viruses are divided into subtypes such as H1N1 and H3N2 according to their:
Subtypes are named from the antigenic types of haemagglutinin (H) and neuraminidase (N) on the envelope.
SARS-CoV-2, the cause of COVID-19, belongs to which virus family?
SARS-CoV-2 is an enveloped positive-sense RNA betacoronavirus of the family Coronaviridae.
Amantadine prevents influenza A uncoating. Which viral protein does it block?
Amantadine blocks the M2 proton channel so the virion interior cannot acidify and release its RNA. Neuraminidase inhibitors are oseltamivir and zanamivir.