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%
How does adenovirus present in infants?
- pharyngitis
- coryza
- otitis media
- pneumonia
- diarrhea
How does adenovirus present in children?
- URI, pneumonia
- pharyngoconjunctival fever
- diarrhea, mesenteric adenitis, hemorrhagic cystitis
How does adenovirus present in adults?
- URI, pneumonia
- epidemic keratoconjunctivitis
Which virus can present as epidemic keratoconjunctivitis in adults and pharyngoconjunctival fever in children?
adenovirus
What is the best way to diagnose adenovirus and why?
- culture of lower respiratory tract
- latent infections may complicate diagnosis (PCR, serology, direct antigen assay)
What virus has a vaccine available for military recruits only?
- adenovirus
What is the most common cause of the common cold?
Coronovirus
Structure of coronavirus?
- ssRNA, positive
- envelope from infected cells
Unique structural aspect of coronaviruses?
- spike proteins: mediate receptor binding and fusion; primary antigen stimulating protective humoral/CMI
When and how do coronavirus infections occur?
- fall/winter
- respiratory droplets and direct contact with infected secretions
How is coronavirus diagnosed and treated?
- clinically
- NO treatment – WASH HANDS
What are the top two causes of the common cold?
- coronavirus
- rhinovirus
Rhinovirus structure?
- very SMALL
- naked
- ssRNA, +
What family does rhinovirus belong to?
picornavirus (Hep A, enterovirus)
When and how do rhinovirus infections occur?
- spring, summer, early fall
- secretions and aerosolized particles
Where does rhinovirus like to be on the human body?
- nasal mucosa - prefers cooler temperatures (33 degrees)
Diagnosis and treatment of rhinovirus infections?
- clinical
- none; wash hands + symptomatic relief
Structure of bocavirus? Family?
- naked icosahedral capsid
- ssDNA
- parvovirus
What does bocavirus do in the body?
URT and LRT infections and gastroenteritis
Two common reoviridae?
- reovirus = respiratory
- rotavirus = GI
Reovirus structure?
- naked
- segmented dsDNA
Manifestation of reovirus?
mild URTI
How does anti-viral amantidine work?
- blocks uncoating process, exact MOA unknown (may inhibit M2 ion channel)
- better for prophylaxis
What two drugs inhibit neuraminidases? Why are neuraminidases important?
- oseltamivir, zanamivir
- disaggregate viruses so that they can be released
