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Questions and Answers
What type of infections are most commonly caused by adenovirus?
Which group is at the highest risk for severe disease caused by adenovirus?
What severe neurological condition is primarily linked to JC virus in immunocompromised individuals?
What factor contributes to the persistence of adenovirus in immunocompromised patients?
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How is JC virus primarily acquired?
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What is a common mode of transmission for respiratory viruses?
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Which organ systems can respiratory viruses infect beyond the respiratory tract?
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Which symptom is commonly associated with a severe upper respiratory infection caused by adenovirus in infants?
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What is a key characteristic of rhinovirus infection in upper respiratory tracts?
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Which cellular receptor is predominantly targeted by RV-A and RV-B for rhinovirus entry?
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What factor may impair the protective effect of maternal neutralizing antibodies in infants against RSV?
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How does RSV evade neutralizing antibodies during infection?
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What is a potential consequence of rhinovirus infection in atopic individuals?
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What is the nature of immunity against RSV after natural infection?
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Which condition may result from RSV infection in newborns?
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What affects the transfer of maternal IgG antibodies to the fetus?
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Which virus is primarily associated with causing respiratory tract infections in infants and young children?
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Which of the following viruses is NOT primarily restricted to respiratory infection?
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Study Notes
Rhinovirus
- Causes infection of the upper respiratory tract, usually limited to the area
- In babies and young children, lower respiratory tract (LRT) infection can cause severe illness
- Distinctive from other Enteroviruses in its low virulence
- Classified into 3 species: RV-A, RV-B and RV-C
- Uses 3 different receptors to enter respiratory epithelial cells
- Majority of RV-A and RV-B viruses use ICAM-1, which is a target for antiviral treatments
- Infection can aggravate disease in individuals with allergies
- Immune response in allergic individuals leans towards Th2:
- Increased production of cytokines that enhance expression of ICAM-1 on the surface of bronchoepithelial cells (BECs)
- BECs in atopic asthmatics produce reduced levels of antiviral cytokines, leading to more severe HRV infection
Respiratory Syncytial Virus (RSV)
- Infects the respiratory tract but does not spread systemically
- In newborns, infection can be deadly due to airway obstruction caused by virus-induced pathologies
- Maternal antibodies provide passive protection, which is affected by premature birth, low birth weight, maternal HIV infection, placental malaria, and maternal hypergammaglobulinaemia
- Long-term immunity is not present, and reinfection can occur after a natural infection
- Maternal hypergammaglobulinaemia can impact transplacental IgG transfer as high levels of non-specific antibodies can saturate the finite number of Fc receptors at the placental interface
- RSV proteins interfere with the host immune response:
- High glycosylation and structural variability of surface G-protein allows evasion of neutralizing antibodies
- Soluble G-protein, released during viral replication, binds anti-RSV antibodies, reducing the amount available for neutralization
- Soluble G-protein also inhibits TLR-mediated Type I IFN production
Rubella
- Causes viremia and systemic infection
- Antibodies limit viral spread via viremia.
- Commonly seen in neonates.
- 50 serotypes exist.
- Causes upper and lower respiratory tract infections, an erythematous rash, and may infect respiratory, digestive, and ocular tracts.
- Less frequent complications include hepatitis, cystitis, colitis, and meningoencephalitis.
- Transmitted through droplets, fecal matter, and fomites.
- Spread via close contact and poorly sanitized swimming pools.
- Vulnerable populations include young children, daycare centers, military camps, and swimming clubs.
Adenovirus
- Infects mucoepithelial cells in respiratory and gastrointestinal tracts, and the cornea.
- Usually causes mild upper respiratory tract infections, but can lead to severe bronchopneumonia in infants and croup.
- Accounts for approximately 5% of childhood respiratory infections.
- Keratoconjunctivitis is highly contagious during the acute phase.
- High mortality rates in immunocompromised individuals (HIV, solid organ transplant) with disseminated disease.
- Persists in lymphoid tissue (tonsils, adenoids, Peyer's patches) in immunocompromised people.
- Type I interferon and IFN-gamma are suppressed by infection.
- Effective Human adenovirus (HAdV)-derived vectors are limited by pre-existing humoral immunity against HAdV due to its high seroprevalence.
JC Virus
- Acquired through the respiratory route.
- Spreads to kidneys in early life in a disseminated infection.
- Persistent and latent infection is established in organs including lungs, brain.
- Reactivation and replication occur in immunocompromised individuals.
- Causes progressive multifocal leukoencephalopathy (PML), which destroys oligodendrocytes and leads to demyelination.
Summary
- Viral infections of the respiratory tract are prevalent.
- Many respiratory viruses are ubiquitous, circulating continuously and leading to lifelong exposure.
- Many respiratory viruses infect both upper and lower respiratory tracts and can cause more severe illness in specific groups, including young children and individuals with compromised immune systems.
- Many respiratory viruses become systemic infections, impacting multiple organ systems and causing severe, potentially fatal disease.
- Viral infections of the CNS, resulting in meningitis and/or encephalitis, are unusual outcomes of common infections.
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Description
This quiz covers critical aspects of Rhinovirus and Respiratory Syncytial Virus (RSV), focusing on their effects on the respiratory tract, especially in infants and individuals with allergies. It explores their mechanisms of infection, classification, and immune response implications. Test your understanding of these viral infections and their clinical significance.
