Viruses Flashcards
What are 4 common attributes of respiratory viruses?
- worldwide distribution
- short incubation periods 1-4 days
- direct (droplet nuclei) and indirect (hand, fomite) transmission
- risk of bacterial superinfection because of damage to epithelial surfaces
Five paramyxoviruses?
RSV, parainfluenza, metapneumovirus, measles, mumps
Paramyxo structure?
- enveloped
- ssRNA, negative, NON-segmented
Difference between RSV and influenza?
- stable antigenically (non-segmented ssRNA -)
- CANNOT survive long outside host
What two glycoproteins are involved in RSV pathogenesis?
- G = attachment to respiratory cell surfaces
- F = fusion of viral envelope with host cell (causes cells to fuse = syncytium formation)
- NO H&N
When do RSV outbreaks occur? Spread?
- late fall to early spring
- droplet nuclei and direct contact
Location, incubation and shedding of RSV?
- upper and lower respiratory tracts
- 2-4 days
- 1-2 weeks (longer in infants)
What is the most common viral cause of otitis media?
RSV
Who gets RSV?
- young children
- older adults with chronic lung/heart disease
- immunity WANES (humoral and CMI)
How does RSV commonly present?
- cold-like symptoms
- bronchiolitis and pneumonia in infants <1 year
- may trigger asthma
What virus is associated with the development of asthma?
RSV
How is RSV commonly treated? Special cases?
- supportive care
- RSV-IVIG: humanized murine monoclonal AB used in young, immunocompromised children
What are the top two most common causes of lower RT disease in young children?
- RSV
- parainfluenza virus (PIV)
What is the most common cause of croup (laryngotracheobronchitis)? What is unique about this serotype?
- PIV serotype 1 - largest outbreaks; most common; biennial ODD years
- 4 serotypes total
What virus is very similar to RSV?
PIV
What happens to immunity to RSV and PIV?
- wanes quickly (neither completely protective nor durable)
- re-infection is common - usually MILDER
When are infections with metapneumovirus most severe?
- typically mild illness
- co-infection with RSV (bronchiolitis, pneumonia) and lung/hematopoietic transplants
When and how do metapneumovirus infections occur?
- winter/spring pattern
- close contact spread
Which viruses are naked, icosahedral, dsDNA with NO seasonality?
- adenoviruses
What is unique about adenovirus structure?
- fiber proteins stick out and effect binding to mucosal cell
- penton base facilitates internalization
Transmission and survival of adenoviruses?
- droplet nuclei, FECAL-ORAL
- hardy and survive prolonged periods in environment (swimming pools, eye meds)
How does adenovirus affect epithelial cells?
- necrosis and sloughing
- inflammatory response may be significant
- sloughing associated with secondary bacterial pneumonia
- viremia may occur
Which virus may exist as a latent infection for years?
adenovirus - not a lot of reactivation
What percent of adenovirus infections are asymptomatic?
50%
