RHS09 - Respiratory Tract Infections 2 Flashcards
What type of genome do adenoviruses have and are they enveloped or not? Whats an easy way to remember this?
- linear, ds DNA
- Non-enveoloped
Adeno kinda sounds like DNA and ends in NO for non-enveloped
Fill in boxes and say what kind of virus this is? Why does this matter?
Adenoviruses
Those fiber proteins and penton bases determine the serotype of the virus, which determines the nature of tissue tropism (which tissues it infects) and disease (course and symptoms)
What are the most common types of tissues infected by the adenovirus and what is the resultant type of infection?
- Mucoepithelial cells - lytic infection
- Adenoid tissue - latent infection
Key characteristics to know about adenoviruses for identification.
- dsDNA virus
- Rapidly killy cells
- Can agglutinate RBCs
- Intranuclear basophilic inclusion bodies in an infected cell
- In addition to common cold symptoms, look for these possible other symptoms (it doesn’t just infect the URT).
- Sore throat & inflamed eye
- Gastroenteritis (diarrhea)
Epidemiological facts to know about adenovirus
- Endemic throughout the year
- Typically affects children from infancy to school age. Also affects young adults in a setting of close quarters or under stress
- There is a vaccine against types 4 & 7 for miliatry personnel because it is so common in them
Describe the pathogenesis of an adenovirus infection.
- Fiber protein attaches to a host cell receptor
- Virus is internalized via receptor mediated endocytosis
- Pento base has toxic activity
- Viral genes first inhibit host cell immune response and then take over the cell machinery
- Cell becomes rounded, enlarged, and begins to aggregate with other infected cells
- Eventual cell lysis by pentonbases leading to tissue damage
- Pleuritic chest pain and/or dyspnea means not a URTI
- Previous common cold means probably rhin-, adeno-, or coronavirus
- Lower lobe consolidation means probably pneumonia (exam Qs won’t tell you it’s pneumonia), which likely means secondary bacterial cause of his current symptoms (So not A or C).
- The answer is E because all the other answers give features of the host, not of the virus
Key characteristics to know about coronaviruses for identification.
- Very large (+) ssRNA virus
- Winter time
- Usually only infects the URT
- Hemagglutination in vitro
- Uniformly surrounded by spike proteins that look like a crown (corona) on EM
- Helical nucleocapsid envelop
Epidemiological facts to know about coronavirus
- Second most common cause of common cold but also causes middle east respiratory syndrome (MERS) and servere acute respiratory syndrome (SARS)
- Incidence peaks in winter
- We never develop immunity agains a serotype because it mutates while replicating in a host cell
List the major human corona virus proteins and what they do.
- E2 - bind a fuse to host cell
- H1 - hemagglutination
- E1 - transmembrane protein
- L - RNApol
Describe the pathogenesis of a coronavirus infection.
Specific details remain unclear but:
- E2 spike protein binds and fuses to host cell
- Replication occurs in cytoplasm
- Virus is assembled and retains its envelope from the ER, not PM
What is the survival time for adeno-, rhino-, corona-, and RSV on dry inanimate surfaces?
- Adeno - 7 days to 3 months
- Rhino - 2hrs to 7 days
- Corona - 3 hours
- RSV - up to 6 hours
What does SARS stand for? What family of virus causes SARS?
Severe Acute Respiratory Syndrome
Coronavirus
What are the criteria for diagnosing SARS?
- H/O fever
- One or more Sx of LRTI and radiologic evidence of pneumonia/ARDS
- Definite contact with a diseased person or there is clear epidemiological evidence of geographic correlation (China, Taiwan, Singapore, Thailand, Vietnam)
- Lab diagnostics based on serology or PCR
What is the reservoir, transmission route, and incubation period for SARS?
- Reservoir - Bats
- Trasmission - Respiratory Droplets
- Incubation Period - 2 to 10 days
D
