Respiratory Pathogen Viruses Flashcards
Rhinovirus
Picorna-viridae. +ssRNA, naked. icosahedral. Rhino: acid labile, growth at 33.C
Human and chimpanzee
PATIENT: common cold (many serotypes)
- host cell receptor ICAM-1 [intracellular adhesion molecule].
- infected cells produce histamine and bradykinnin
TX. Clinical. supportive. wash hands.
Coronavirus
Corona.viridae. +ssRNA, enveloped, helical.
Human (birds small mammels). respiratory droplets
PATIENT: common cold or SARS: atypical pneumonia (patchy interstitial infiltrates), high fever, dry cough.
- “crown” of glycoproteins:
- S protein (similar to Fc-gamma-R) binds sialic acid on host cell neutralized by Abs.
- Hemagglutinin molecules make up peplomer on virus surface
TX. Ab to SARS-CoV, RT-PCR, viral isolation culture. supportive (ribavirin and interfreon)
Adenovirus
**adeno-viridae. dsDNA, naked, Icosahedral. (pentons) ** >50 serotypes. resist dry, detergents, mild chlorine (survive ~90days in poorly chlorinated pools)
ubiquitous to animals and human asymptomatic shedding. respiratory, fecal/oral, direct contact, fomites
PATIENT: pharyngoconjuntival fever, nonpurulent (pink eye-pools), acute respiratory disease-ARD (pneumonia- military vaccine 4,7-21), daycare viral gastroenteritis diarrhea (viral enterocolitis).
- Hemagglutinin: penton fibers. (fibers toxic to cell)
- Immune avoidance: inhibit interferon response, block apoptosis, reduce MHC1 (n.b. apaptosis by NK, CD8, TNFalpha)
- receptor mediated endocytosis. CAR: coxsackie adenovirus receptor (Ig superfamyli glycoprotein), CD46, MHC1, integrin, sialic acid
- lytic in permissive cells,
- latent in nonpermissive cells causing recurrence in immno compromised patients (tonsils) ,
- transforming infection cause cancer in hamsters (by inactivating growth suppressor proteins).
TX. serology/ELISA. supportive care. live non-attenuated vaccine.
Coxsackie A
Picornaviridae, +ssRNA, naked, Icosahedral. Enterovirus: acid stable
Human, fecal-oral, airborne, formites.
PATIENT: under 9yrs, no diarrhea. Hand-foot-mouth (A16). Herpangina: vesicular rash and ulceration pharyngitis.
TX. virus isolation form throat, stool, CSF. supportive. wash hands.
Epstein Barr Virus
Herpesviridae, dsDNA linear, enveloped, Icosahedral. spp: gamma subgroup. HHV4.
Human. 90% seropositive asymptomatic shedding saliva.
PATIENT: asymptomatic childhood - teens are symptomatic. Acute disease: infectious mononucleosis“kissing disease”. fever, sore throat exudative pharyngitis (grey white membrane on tonsils), lympadenopathy (involving postirior auricular nodes), hepatosplenomegally, fatigue (1-4wks). Chronic: recurrent cycles fatigue, low fever, headache, sore throat.
Immunocompromiseg PATIENT: lymphoprolipherative disease. Tcells can not control Bcell proliferation. AIDS patients have hairy oral leukoplakia hyperproliferation of lingual epithelial cells
- infectets epithelial (permissive lysis) and latent (nonpermissive) infection of bcells.
- EBV DNA in nucleus but not in chromosome. Infected cells have EB nuclear antigen (EBNA) and latent membrane protein (LMP).
-
B-cell mitogen: viral gp350 -binds- CD21 (CR2) complement C3b receptor
- production atypical Downey Type II CD8 Tcells. (look like monocytes)
- production of heterophile Abs (monospot test IgM)
- viral gp42 - binds - to MHC II phago cells.
- leukemia/lymphoma (T-cell difficient patients/immunosuppressive),
- Burkitt lymphoma (B-cell tumous t8:14 C-Myc) africa/malaria belt.
- nasopharyngeal carcinoma (epithilial cell cancer) Asia.
- Oral hairy leukoplakia (AIDS wart of the tongue)
TX. ampicillin gives rash. self limiting disease. supportive.
Parainfluenza
Paramyxoviridae. –ssRNA, enveloped, Helical.
Human. Respiratory inhalation.
PATIENT: Croup, laryngotracheobronchitis. seal bark (subglottal swelling) . xray-steeple of narrow upper trachea.
-
Fusion protein destabilizes host membrane
- syncitia: epithelial cell replication, giant cell multinucleated
- F spikes with hemaglutinin surface glycoprotein binds sialic acid receptors
- neuraminidase clips off sialic acif for release
TX. RT-PCR. hospitlization. croup tent, O2, corticosteird and epinephrine.
Respiratory Syncytial Virus
Paramyxoviridae –ssRNA, enveloped, Helical.
Human. respiratory inhalation.
PATIENT: Forms plugs of mucus, fibrin, necrotic material that obstructs airway (bronchilitis) with prominent intercostal or sub-sternal retraction.
- F-fusion peplomer forming epitelial mutinucleted syncytia
- Pneumovirus genus G protein for attachment
-
NO hemagglutinin
- Type B assymptomatic,
- Type A symptomatic (young children under 1yr - fatal - turns to asthma)
TX: IFA. ELISA. TR-PCR.
- bronchodilators. oxygen,
- Ribavirin (aerosol nucleoside analogue of guanosine)
- anti-RSV Abs. (passive immunity)
- Palivizumab (block Fusion protein prophylaxis)
- Respigam (hyperimmune globin)
Metapneumovirus
Paramyxoviridae. –ssRNA, enveloped, Helical.
Human. Respiratory inhalation
PATIENT: common cold. bronchitis, bronchiollitis, pneumonia (almost all 5yr old are seropisitve)
- Fusion peplomer creats syncytis
TX. RT-PCR. supportive.
Influenzavirus
orthomyxoviridae. –ssRNA, envelopped, Helical. 8 segments (nucleus replication for 5’meth cap)
typeA (birds, pigs, human) typeB (human): Respiratory, direct contact formites.
PATIENT: headache, malaise, fever, chills, myalgia, anorexia, cough. May lead to secondary bacterial pneumonia. Children may have bronchiolitis, croup, otitis media, vomitting (Aspirin with virus: Reyes syndrome)
- Epidemic: Antigenic drift in type A and B mutations in Matrix protein or Heamglutinin
- Pandemic: Antigenic Shift in type A gene reassortment with coinffections.
- 8 segmentes RNA including:
- Hemagglutinin peplopers (binds sialic acid of epithelial cells (agluts RBC) [Ab to HA prevent infection]
- Neuraminidase peplomer (release of virus cleaves sialic acid, dissolves mucus layer) [Ab to HA prevent spread]
- Matric proteins
- N inhibitor: Zanamivir/relenza (inhaled) Oseltamivir (oral)
- M2 typeA inhibitor: Amantadine/rimantadine
- Vaccine: killed - shot
- Vaccine: live attenuated - nasalspray
