Lec 25 Resp Viruses Flashcards
(63 cards)
1
Q
What does palivizumab treat?
A
RSV infections
2
Q
What does ribavirin treat?
A
RSV infections
3
Q
What does cidofivir treat?
A
adenovirus infection
4
Q
What are the respiratory viruses we are responsible for?
A
Parainfluenza (hPIV) Respiratory Syncytial Virus (RSV) Metapneumovirus (hMPV) Influenza Coronavirus (hCoV) Adenovirus Rhinovirus
5
Q
What type of virus is measles?
A
morbillivirus
6
Q
what type of virus is parainfluenza?
A
paramyxovirus
7
Q
What type of virus is respiratory syncytial virus [RSV]?
A
pneumovirus
8
Q
What type of virus is metapneumovirus?
A
pneumovirus
9
Q
Paramyxoviruses: what sense, strandedness, DNA/RNA?
A
- negative sense
- single stranded
- non-segmented RNA
10
Q
What are the 3 proteins of paramyxovirus nucleocapsid?
A
helical nucleocapsid with 3 proteins
- nucleoprotein [NP]
- polymerase phosphoprotein [P]
- large protein [L]
11
Q
What are the glycoproteins in the lipid bilayer of paramyxoviruses?
A
- fusion protein [F]
- attachment proteins [HN, H, G]
12
Q
How do paramyxoviruses replicate?
A
- attachment proteins bind to sialic acid on cell surfaces
- genome transcribed into individual mRNAs and full-length + RNA template
- nucleoplasmid associated with matrix and plasma membranes and leaves by cell budding
13
Q
What are the clinical symptoms of parainfluenza virus?
A
- primarily in young children get upper and lower respiratory tract infections
- –> croup, common cold, bronchiolitis, pneumonia
- community acquired resp tract infection in adults
14
Q
What are the types of parainfluenza virus that most commonly cause croup?
A
HPIV-1, HPIV-2
15
Q
What is pathogenesis of parainfluenza?
A
- infects nasal and pharyngeal mucosal epithelia
- spread locally along respiratory epithelium to larynx and trachea
16
Q
What is the steeple sign?
A
narrowing of trachea in subglottic region
= sign of croup
17
Q
How is parainfluenza transmitted?
A
respiratory droplets or direct person-person contact
18
Q
When do serotypes 1-4 infections occur primarily
A
HPIV-1 and HPIV-2: fall
HPIV-3: through year, peak in spring
HPIV-4: no well-defined infection pattern
19
Q
How is parainfluenza diagnosed?
A
- antigen detection: direct fluorescent antibodies [DFA] or ELISA
- cell culture
- PCR
20
Q
What is treatment for parainfluenza?
A
normally self-limited, give supportive treatment
21
Q
What is treatment for croup?
A
- IV/IM/oral dexamethasone [steroid]
- for more serious: nebulized racemic epinephrine
22
Q
What are clinical syndromes of RSV virus?
A
- bronchiolitis or pneumonia [most common cause of bronchiolitis in kids < 2 yrs old]
- usually upper respiratory tract disease
- lower respiratory diseases in older children and adults
23
Q
Who is at increased risk for severe RSV?
A
- preterm birth
- congenital heart diseases
- chornic lung disease of prematurity
- immunodeficiency
24
Q
How is RSV transmitted?
A
- by direct contact with contaminated secretion or fomite, persist on environmental surfaces/hands for hours
25
When are RSV outbreak?
- winter and early spring in temperate climates
26
How is RSV diagnosed?
rapid antigen test [fast but not that sensitive]
also: DFA, cell culture, PCR
27
What is treatment for RSV? for not severe? for severe?
if not severe: supportive
if severe/immunocompromised: ribavirin [oral, IV, aerosolized forms]
28
What is ribavirin? mech of action? what is downside?
- nucleoside analog that inhibits nucleic acid synthesis
- used to treat RSV
- comes in oral/IV/aerosolized form
- its a teratogen so can't be administered near pregnant women in aersolized form
29
What are ways to prevent RSV?
- give palivizumab = monoclonal antibody against RSV F protein
- infection control = use contact precautions
30
What is palivizumab?
- monoclonal antibody against F protein of RSV
- gives passive immunity to high risk infants
- reduces hospitilization rates
- give monthly IM during peak season [nov - march]
31
What is pathogenesis of RSV?
- replicates in nasopharynx then infects bronchiolar epithelium
- extends to alveolar pneumocytes by cell-cell spread, aspiration of secretions, formation of syncytia!!!
- necrosis of bronchi and bronchioles causes mucus plugs to form
32
What are the first and second leading cause of bronchiolits in infants?
first: RSV
second: human metapneumovirus
33
What are clinical syndromes associated with human metpneumovirus?
- bronchiolitis in infants
- 15% of common colds in children
- pneumonia, croup, URIs
34
Who is at risk for severe hMPV?
- immunocompromised
- preterm birth
- transplant
- cardiopulmonary disease
35
How is human metapneumovirus [hMPV] transmitted?
- direct or close contact with contaminated secretions
| - some health-care associated infections
36
When do hMPV infections occur?
late winter/early spring in temperate climates
37
how is hMPV diagnosed?
PCR
antigen detection
cell culture [but difficult to grow and requires long incubation]
38
What is structure of coronavirus?
- enveloped
- single strand
- positive sense
- RNA
- glycoproteins form halo-like projections that surround envelope = corona
- RNA genome plus N protein form helical nucleocapsid
39
How if hMPV treated?
supportive
40
How is coronavirus replicated?
- uses E1/E2 attachment proteins to bind cell
- virus fuses with cell and genome is released in cytoplasm
- translation of genome in two phases
- ---- early phase: produces RNA polymerase
- ---- late phase: negative sense RNA yields struct and non struct protein
- forms into vesicle at RER
- released by exocytosis
41
What clinical syndromes associated with coronavirus?
- common cold and other resp infections
- gastroenteritis
- SARS
42
What are signs of SARS? possible cause?
- can be due to coronavirus
- fever, pneumonia/resp distress, diarrhea, leukopenia
- 10% mortality
43
How is coronavirus transmitted?
- reservoir may be in animals
| - transmitted by resp tract secretions via person to person contact or fomites
44
When do coronavirus infections occur?
- some sporatic
| - outbreaks in winter/spring
45
What is MERS?
- middle east respiratory syndrome
- newly recognized pathogenic coronavirus
- no treatment currently
46
How is coronavirus diagnosed?
- PCR [respiratory, stool]
- antibody assays
- electron microscopy
47
What is treatment for coronavirus?
- supportive care
- steroids used to treat SARS-CoV associated respiratory distress syndrome [ARDS]
- no treatment for SARS
48
Where does transcription/translation occur in DNA viruses?
in nucleus
49
What is structure of adenovirus?
- linear
- double stranded
- DNA
- non-enveloped
- icosadeltahedron shape
50
How does adenovirus replicate?
- viral fibers attach glycoprotein member of Ig superfamily
- penton base interacts with integrin on host cell [helps endocytosis]
- DNA genome goes to nucleus
- transcription of mRNA in two phases
- capside proteins produced in cyto and transported to nucleus for viral assembly
- virus remains in cell and released when cell degenerated and lyses
short form: everything happens in the nucleus
51
What clinical syndromes associated with adenovirus
immunocompetent: pharyngitis + conjuctivitis [pink eye]
also: URI/LRI, gastroenteritis, cysitis
imunocompromised = more severe disease: pneumonia + respiratory failure, meningitis, encephalitis
52
How is adenovirus transmitted?
- by aerosol, close person-person contact, fecal-oral, fomites
- very contagious!
53
what is pathogenesis of adenovirus infection?
- virus establishes pharyngeal infection
- infects mucoepithelial cells in respiratory tract, GI, conjunctiva/cornea
- virus persists in lymphoid tissue
- viremia can occur if local replication
- then spreads to visceral organs
54
Where and when do adenovirus outbreaks occur?
in congregate settings --> military
| no seasonality [all year round]
55
How is adenovirus diagnosed?
DFA
culture [for some serotypes]
PCR
56
How is adenovirus treated?
- usually supportive
| - cidofovir for some immunocompromised
57
What is cidofovir? mech? type of administration? side effects?
- cytosine analog
- serves as substrate and inhibits viral DNA synthesis
- used to treat adenovirus in immunocompromised patients
- clear benefit has not been demonstrated
- IV administration
- side effect: nephrotoxic
58
What are clinical syndromes associated with rhinovirus?
- most frequent cause of common cold
- pharyngitis
- otitis media
- less commonly: bronchiolitis, pneumonia
59
what is the most frequent cause of common cold?
rhinovirus
60
How is rhinovirus transmitted?
aerool/droplets, fomites
| hands are major vector!!
61
When do rhinovirus infections primarily occur? in which patients?
- in autum and late spring
| - highest in infants and children
62
How is rhinovirus treated?
supportive
63
how can rhinovirus be prevented?
hand washing, disinfection contaminated objects
