influenza virus & parainfluenza virus.english
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Influenza A, B, C viruses● Classification, Composition, Genome, Biology - Family Orthomyxoviridae Influenza A subtypes : 16 distinct HA & 9 distinct NA ( ~ outbreaks in humans : H1-3 & N1-2 )
- Virion (spherical) : a. Segmented, minus strand RNA b. Helically coiled nucleocapsid c. Enveloped (hemagglutinin & neuraminidase glycoprotein
spikes)
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Zuckerman et al, 2009. Principles & Practice of Clin Virol. Wiley-Blackwell
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- Genome :13000-15000 nt, 7-8 segments (reassortment !); which code 10-11 different proteins. Influenza C virus : NA gene Ө
Example : A/Johannesburg/33/94(H3N2)
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- Primary cell cultures including monkey kidney cells - Host : Influenza A virus : wild avian, humans, swine, horses
(note : all known HA & NA subtypes) Influenza B & C viruses : humans : swine, dogs, cats, horse- Inactivated by : ionizing radiation, pH <5 / >9, >50C, ionic & non ionic detergents, organic solvents, drying
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● Epidemiology - Worldwide (all age groups); outbreak : unpredictable 9 pandemik : Influenza A virus H1N1 (swine) 1918, H2N2 (Asian) 1957, H3N2 (Hongkong) 1968, H5N1 (chicken/bird) 1997 1947 : WHO surveillance program
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- New strain ~ outbreak/pandemic (>>Influenza A virus) Changing antigenecity : antigenic shift (HA ± NA) &
antigenic drift (HA/NA)
- Influenza A virus : > avian; ~ epidemic (swine as an intermediate host)
: non human & human (reassortment!) Influenza B & C viruses : ~ milder disease; winter outbreaks
- Seasonal : (~ humidity) winter / spring (temperate) & year round : rainy season (tropics).
(Influenza C virus : non seasonal)
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- Low mortality (~ lower respiratory/ cardiovascular disease) - Transmission : by airborne droplets (person-to-person,
zoonotic infection) - Reinfection >> - Nosocomial infection (~ Influenza A virus)
● Clinical Manifestation - Incubation period : 1-5 days Influenza syndrome (all age groups) - Complication : common (otitis media/sinusitis, bronchitis, croup, pneumonia, CNS, myocarditis, acute renal failure)
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● Lab Diagnosis - Virus isolation from sputum, nose/throat swabs, nasal aspirate/washing (cell culture) & CPE detection and hemadsorption - Nucleic acid detection (RT-PCR) - Serology tests : to detect ag & ab (IF, EIA, HAI)
● Prevention (vaccine, patient isolation : in hospital, antiviral)
● Treatment (symptomatic dan antiviral : Amantadine, Rimantadine, Oseltamivir ~ H5N1 resistant !!)
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Parainfluenza virus● Classification, Structure, Genome, Biology - Genus : Respirovirus & Rubulavirus,
Family :Paramyxoviridae Types of HPIV : 1, 2, 3, 4 (subtypes A & B)
- Virion : pleomorphic (spherical/filamentous) : a. Single stranded of negative sense RNA b. Helical nucleocapsid c. Envelope (spike-like glycoproteins & lipid from host cell)
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- Genome : 15500 nt which code : 6 VP (HN = Hemaglutinin-Neuraminidase,
M = Matrix F = Fusion)
& 1 NSP - Primary cell cultures : i.e Hep-2 cells , monkey kidney cells
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● Epidemiology (~ age, seasonality, clinical manifestation) - Worldwide (early childhood) mortality : ~ pneumonia (children <5 y.o)
in developing countries - HPIV type 1 : croup epidemics (~ autumn) 2 : ~ PIV type 1 (milder) 3 : sporadic, least predictable (late winter &spring) in tropics : rainy season - Transmission : droplet (port d’entry : nose & eyes) close-contact transmission &
surface contamination
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- Host range : humans. - Host factors : age & immunodeficiency - Immunity : not long lasting - Reinfections : common (HPIV type 3) - Nosocomial infections (HPIV type 3)
● Clinical Manifestation : - Upper resp. tract infection: “croup”
(laringotrakheobronchitis) Lower resp. tract infection (bronchiolitis & pneumonia) - Complications : otitis media, bacterial pneumonia
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MANDELL, DOUGLAS, BENNETT’S. 2010. PRINCIPLES & PRACTICE OF INFECTIOUS DISEASES 7th ed Churchill Livingstone
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● Lab Diagnosis - Specimens : nasal wash/ nasal aspirate, nasopharyngeal swabs, BAL - Virus isolation, CPE detection and hemadsorption - Serology tests : ag (IF) & ab (CFT, HI) - Nucleic acid detection (RT-PCR)
● Prevention (vaccine ~ HPIV tipe 3, handwashing, glove-goggle-masker-gown)
● Treatment (supportive, no licensed antiviral)