Resp Viruses Flashcards

Question

RNA virus (enveloped) Parainfluenza Clinical

Answer 1

* **_Transmission:_** inhalation of large droplet * **_High risk:_** Children 6mos-12yrs, short term immunity after disease * **_Pathogenesis:_** Inside epi cells-form giant cell & lysis * ***Adhesion mediated*** by Hemagglutnin-binds to sialic acid * ***Neuraminidase clips*** sialic acid for virus release * **_Clinical:_** Croup & Laryngotraceobronchitis * Mild cold-like upper resp infection * Can extend to larynx, trachea, & ***bronchial tree = CROUP*** or bronchiolitis & pneumonia * **_Croup=_**cough is sharp like seal's bark due to ***subglottal swelling=High pitch*** * ***X-ray steeple sign***

Answer 2

* Best specimens are ***nasopharyngeal secretions*** * **_Ag detection:_** Immunofluorescence * **_Serology:_** Hemagglutination inhibition test, ELISA * **_Treatment:_** * ***Hospitalization-***Treat symptomatically & monitor airway continuosly * ***Cold or warm mist*** (humidirfier)-***Croup tent*** * O2-may have intubated due to narrowing of trachea * ***IM dexamethasone*** (corticosteroid) & inhaled epinephrine (pediatric) * NO vaccine & re-infections common

Answer 3

* (-) ssRNA w/surface spikes only F protein (NO HG or Neuraminidases) * **_F protein:_** fusion multinucleated (syncytia) * **_Reservior_**: Humans ***everyone infected*** by age 3 * **_Subtype B:_** asymptomatic affect majority of population * **_Subtype A:_** More severe & ***dominant in most outbreaks*** * **_Transmission:_** Inhalation of large droplets-***Peaks in winter*** * **_High Risk:_** ***Premies-more severe*** w/lower resp=Brochiolitis * Common cause of ***acute FATAL resp tract*** infections * **_Adults:_** Mild symptoms, common-cold like. Very few infections are life threatening

Answer 4

* Cause of ***fatal acute resp tract infection*** in infants * Infects epi cell & make giant cells & kills cells * Immuno mediated ***(CD-8)*** cell injury-***necrosis/sloughing of bronchiolar epi*** * ***Formation of plugs-***Mucus, fibrin, necrotic material obstructs airway=***Bronchiolits*** * More dangerous in infants due to ***smaller peripheral airways*** than adults * **_Symptoms:_** Mild Upper resp infection progress to cough-\>wheeze-\>dyspnea * Increased resp rate=***Tachypnea*** * Rales, fever-\>turns into ***Lower resp=Pneumonia*** * **_RSV sign:_** ***intercostal/substernal retraction*** * **_Long-term=_**Asthma & pulm deficits

Answer 5

* Ag detection assays (immuno)- * Cytophatic effect=***Multinucleated cells*** w/basophilic cytoplasmic inclusion bodies * **_Treatment:_** * ***Symptomatic-***Bronchodialators (metaproterenol/Albuterol) helps relieve chest congestion & wheezing * **Severe cases=**O2 therapy, Aerolized ***Ribavirin*** (analogue of guanosine) * **_Passive immunization:_** Hyperimmune globulin against RSV ***(Respigam)*** * **_Prevention:_** Infection for re-infection * ***Immuno-prophaylaxis-***Children under 2 who have chronic lung disease * Monoclonal Ab against F-protein***(palivizumab)***

Answer 6

* ss(-) RNA from family paramyxoviridae * Recently recognized pathogen * Could cause ***15% of children's colds*** * **_Can cause:_** * Bronchitis (mucous membranes) * Bronchiolitis (small bronchioles) * Pneumonia * ***Very common-***children by age 5 are seropositive

Answer 7

* ss(-)RNA & ***8 Segmented RNA*** * Replicates in nucleus^{(instead of cytoplasm)} * Has ***RNAdep-RNApoly*** * **_Matrix proteins important in uncoating:_** * ***HA (hemagglutinin)*** * Initiate by binding to sialic acid on epi cells * Agglutinates clumping-RBC * ***NA (neuraminidase)*** * Cuts sialic acid to release virus/dissolves mucus * Vaccines target these proteins ***(no binding=no infection)*** * 3 types based on variation of ***matrix proteins & nucleocaspid proteins*** (viral penetration into host nucleus)

Answer 8

1. ***HA sticks to sialic acid on host cell-***Virus enters by fusion into ***endosome*** (storage b4 nucleus) 2. Matrix proteins=uncoating 3. Nucleocapsid to host cell nucleus, ***viral polymerases require methylated cap*** of RNA _^{(Cap-mRNA-Poly A)}_ of host cell. Cap region of RNA for binding to ribosomes. 4. (+) RNA made from each segment=***viral polymerase*** on each segment(-)sense RNA for viral progeny made=**^{viral Shedding}** 5. ***+mRNA proteins*** in cytoplasm. 6. ***Early proteins (polymerases and NP)*** for transcription and replication go to nucleus and ***mix w/–ssRNA.*** 7. ***HA and NA , M proteins*** transported to host cell membrane.

Answer 9

* **_Type A_** ONLY one w/sub-types based on variation on HA/NA Ag * 16 HA sub = ***H1-H16*** * 9 NA sub = ***N1-N9*** * Found in many species_-Native host is duck_ * Type A assoc w/Pandemic ^{(Spanish Flu)} * **_Reassortment Antigenic shift:_** * Abrupt change when 2 strains infect one cell=RNAs mix giving rise to NEW strain * ***ONLY A*** * **_Type B_** ***ONLY humans*** * Point mutation/Antigenic shift: * Type A&B-Yearly epidemics occur * ***RNA segments are altered*** affect major Ag sites for glycoproteins * RNA virus prone to ***more mutations*** than DNA * ***Peplomers mutation***=Cross species infect

Answer 10

* Incubation 1-4 days * Fever, headache, sore throat, muscle pain, ***DRY cough*** * Recovery 7-10 days * Severity in ***young & elderly*** ALSO pts w/chronic cardio-pulm diseases * Pneumonia caused by Influenza * Pneumonia caused by secondary bacterial infection-MOST COMMON ***(Staph aureus, Staph pneumoniae, H. Influenzae)*** * **_Reye's syndrome-_**Acute encephalomyelitis**_^{(inflammation of CNS)}_**in children-assoc w/aspirin use * ***CNS issues-***Seizures, weakness in periphery, hallucinations

Answer 11

* Nasal/throat swabs, sputum * **_Detection=_**Ag/genome DFA, ELIZA, RT-PCR ***specific ID*** for types or subtypes * **_Fast results-_**used in screening during epidemics * **_Viral isolation & ID-Cell/egg culture:_** * Hemagglutination or Hemabsroption assay ***NOT specific*** * **_Serology:_** measure ***Ab lvl (titer)-***Acute hemagglutination inhibition assay, Comp fixation * **_Treatment:_** neuraminidase inhibitors stop viral release given 48 hrs of onset * ***Oseltamivir(tamiflu)-***oral * Zanamivir(Relenza)-inhaled * Stop uncoating-block martix proteins_^{ONLY A}_ * ***Amantadine or Rimantadine***

Answer 12

* **_Flu shot-_**Inactivated vaccine (killed virus) * Composed of H1N1, H3N2 + type B * **_Nasal spray vaccine_**: * Live attenuated=Reconstructed from mutant strain & virulent strain (weak)=***Reassortment*** * Mutant strains does NOT grow well above 25C=***Cold adapted mutant*** * ***Will grow in upper*** BUT not Lower resp making it less virulent