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64 Cards in this Set
- Front
- Back
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what kind of genome do paramyxo viruses have?
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RNA
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what are the three genera of paramyxoviruses?
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paramyxo
morbilli pneumo |
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what kind of viruses are paramyxo viruses?
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parainfluenza (type 1-4)
mumps Newcastle disease virus |
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what does Morbilli virus cause?
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measles
canine distemper |
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what kind of viruses are pneumoviruses?
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RSV--respiratory syncytial virus
human metapneumo (HMPV) |
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what are some general features of paramxyo virus?
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envelope
negative-sense ssRNA RNA transcriptase w/in the virion (like Orthomyxo) |
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what are some features of paramyxoviruses?
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1. adsorption
2. replication NOT inhibited by actinomycin D 3. viral DNA synth in cytoplasm, but only a small amt made into virions 4 assembly and maturation at cell plasma membrane |
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what's the F glycoprotein?
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helps the paramyxo viral envelope fuse with the host
activated by cellular protease followed by release of viral nucleocapsid into cytoplasm (uncoating) |
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what's actinomycin D?
Does it work on orthomyxo or paramxyo? |
inhibitor of DNA dependent RNA synth
orthomyxo |
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where does replication occur in paramyxo?
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in the cytoplasm--doesn't depend on functioning cellular DNA for replication
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where happens after viral RNA of paramyxo is made?
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rapidly associates w/ new nucleocapsid protein
BUT, only a small portion of these nucelocapsids assembled into virions |
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what happens to positive strands of RNA of paramyxo?
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occasionally accidentally assembled into virions and nucleocapsids
appear as cytoplasmic inclusion bodies of infected cells (w/ Measles they're also seen in the nucleus--Negri? body) (w/RSV, inclusions don't contain vRNA or vAg's) |
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where does assembly and maturation of paramyxo take place?
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plasma membrane
regions of thickened cell membranes contain virus specific proteins release by budding |
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what's the M protein?
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in paramyxo, it is assoc. w/ strands of viral nucleocapsid
forms inner layer of viral envelope |
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how many serotypes are there for parainfluenza?
are they cross reactive? can you get re-infected? |
4 serotypes
serologic x-reactivity re-infection common |
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what's the epidemiology for type 1/2 parainfluenza?
type 3? type 4? |
1/2: outbreak in fall
3: endemic, primary infection early in life 4: not well understood |
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how infective are the different serotypes of influenza?
what's the most infectious? |
type 1: 65%
2: 79% 3: 100% (type 3) |
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what age do you get the different parainfluenzas?
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type 3 is very infectious, nearly everyone gets it by age 5
most people get type 1 (74%) and 2 (59%) by the same age. |
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how is parainfluenza transmitted?
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aerosol infected droplets
fomites |
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how does serum and secretory Ab titer correspond to immunity of parainfluenza?
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serum Ab: relationship w/ imm.
secretory: correlate better w/ immunity but poor x-reactive (more specific response) |
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are you protected from a parainfluenza virus once you've had it?
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re-infection induces temporary resistance to lower resp dz to new infecting serotype
protection lasts <1 yr in small kids |
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what kind of Ig do pts w/ parainfluenza bronchiolitis have?
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IgE
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why do pts w/ parainfluenza croup or bronchiolitis have greater CMI response than w/ URI alone?
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suggests lymph hyperresponse may contribute to pathogenesis
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how is parainfluenza diagnosed?
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culture by nasal wash early: CPE w/ type 2 only, can id by hemadsorption (distinguish from infl or mumps w/ anti-sera)
direct fluorescent Ab test rapidly distinguishes type 1,2,3 *most imp't clinically |
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what's the genus of RSV?
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pneumovirus
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what kind of genome does RSV have?
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ssRNA, nonsegmented, encodes >10 proteins
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what are 2 glycosylated surface proteins of RSV that make good targets for the immune system?
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F=fusion
G=attachment |
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how is RSV cultured?
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easily in Hep-2 cell lines (typical CPE: giant cells w/ cytoplasmic inclusions)
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what are the 2 isolates of RSV?
which is more common? |
A and B
70-80% of pt isolates is A both circulate concurrently |
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who gets infected with RSV?
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most infants by 24 mo--usually 1st year (1/3 involve lower resp tract)
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how much trouble does RSV cause?
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commonly causes repeat infection but in URT
only a small % of infants require hospitalization but big number: 100,000/yr and 4500 die |
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who is at the greatest risk from RSV?
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premature infants
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when does RSV occur?
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late fall to early spring, especially in temperate regions
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transmission of RSV?
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humans=only reservoir
DIRECT spread (contaminated secretions) >>importance than airborn inoculation of mucus memb more efficient than the mouth nosocomial important (wash your hands!) |
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incubation period of RSV?
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5 days, 1 wk of viral shedding
but can be longer in infants/immunosuppressed |
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what's the immunity to RSV?
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humoral and cellular response
infants w/ lots of maternalAb less likely to become infected mucosal IgA may be imp't prolonged RSV w/ deficient CMI |
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where does most of the pathology of RSv occur?
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small airways--respiratory epithelium infiltrated by lymphs, plasma cells, macs
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what kind of cells are involved in the formation of syncytia in RSV?
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resp epithelium cells
may see cytoplasmic viral inclusions |
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what causes bronchiolitis in RSV?
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occlusion of small airways: edema, mucous, sloughed debris
causes atelactasis or distal hyperexpansion |
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what's an important factor for pathology in RSV?
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direct viral infection with the HOST immune response
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how is RSV diagnosed? how long does it take?
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nasal washings (2-10 days)
rapid dx w/ ELISA or direct fluoresc Ab test |
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what drug can be given for the tx of RSV?
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ribavarin (synthetic nucleoside) given continuously for 18hrs X 3-5 days
efficacy, potential risk to caretakers controversial |
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What's RSVIG?
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can be helpful to prevent severe dz in high risk infants for RSV
administration difficult |
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what's bronchiolitis?
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inflammatory obstruction of small airways, epithelial necrosis, mucus plugging, airway narrowing
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what kinds of viruses cause bronchiolitis?
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viruses w/ specific tropism for bronchiolar epithelium
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which viruses might cause bronchiolitis?
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RSV (>75% during the season), parainfluenza 3 (25-50%)
parainfluenza 1,2, adenovirus, influenza, mycoplasma, herpes all cause minor numbers of cases viruses w/ specific tropism for the bronchiolar epithelium |
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when does bronchiolitis occur in paramyxovirus respiratory illnesses?
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last stage of respiratory disease.
begins w/ cough, nasal discharge 4-6 days after exposure apnea can occur suddenly |
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who gets bronchiolitis most commonly?
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infants less than 1 yr
pk incidence 2-6 months |
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what's the differential dx for bronchiolitis besides viral causes?
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noninfectious: anatomic abnlitis, cardiac dz w/ pulm edema, CF, aspiration of foreign body
hypersensitivity syndrome |
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how is bronchiolitis diagnosed?
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clinical criteria + CXR findings
rapid viral Ag test (ELISA +/- fluour Ab) |
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what is seen on x-ray in bronchiolitis?
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hyperinflation, hyperlucency, atelactasis (RUQ espec)
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how is bronchiolitis managed?
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hydration, supplement O2
can use: bronchodilators, steroids, spec. antivirals, immune mediators |
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What's croup?
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laryngotracheobronchitis, LTB
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what causes croup?
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most common parainfluenza 1 and 2
type 1= winter epidemics type 3= sporadic, severe also adenovirus, infl, RSV, entero, rhino, bacteria |
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whats the clinical course of LTB (croup)?
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prodrome of mild URI 1-2 days, then barking cough and intermittent respiratory stridor
90% kids recover w/in 3-7 days or progress to cont. stridor, resp. compromise, death |
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what do neck films show w/ croup?
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lateral neck film shows widening of hypopharynx and narrowed subglottic airway
A-P film shows "steeple sign" of subglottic edema and narrowed airway |
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how is croup managed?
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humidity (nebulizer)
racemic epinephrine steroids=controversial |
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what are the most common human respiratory viruses?
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rhino (113 types)
corona (4) adeno (47) influenza (3) parainfluenza (4) RSV (only 1) |
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what are Sx of the common cold?
common cause? |
profuse nasal discharge, obstruction, purulent disch., sneezing, mild sore throat, cough. usually w/o fever
rhinovirus, corona |
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Sx of pharyngitis?
common cause? |
sore throat, cervical nodes, fever, exudate
influenza A and B, parainfl 1-3, adenoviruses |
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common Sx of croup?
common cause? |
partial laryngeal obstruction w/ hoarseness, cough, fever
influ A/B, para 1-3, RSV |
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bronchitis Sx
common cause? |
fever, persist cough, rhonchi, wheeze, rales
inf A/B, para 1-3, RSV |
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bronchiolitis Sx
common cause? |
mostly infants <2, partial block of terminal bronchioles, interfere w/ gas exchange
para 1-3, RSV |
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viral pneumonitis/pneumonia Sx
common cause? |
involve alv interstitial tissue, inflamm compress alveoli and interfere w/ gas exchange (bacteria cause consolidation by filling alveoli)
para 1-3, RSV, adenoviruses |
