virusurile gripale fam ortomy xoviridae
DESCRIPTION
Virusurile gripale Fam Ortomy xoviridae. (myxa = mucus) → afinitate pentru mucine, receptori mucoproteici trei tipuri de virusuri gripale: A – 1933 (prima inoculare la dihori apoi şoareci adulţi i.n. → pneumonie B – 1940 C – 1949 - PowerPoint PPT PresentationTRANSCRIPT
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Virusurile gripale Fam Ortomyxoviridae
• (myxa = mucus) → afinitate pentru mucine, receptori mucoproteici
• trei tipuri de virusuri gripale:– A – 1933 (prima inoculare la dihori apoi
şoareci adulţi i.n. → pneumonie– B – 1940– C – 1949
• 1941 – descoperit capacitatea hemaglutinantă a v. gripale (R. Hirst)
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V. gripal A • epidemii (intervale de 2-3 ani) • pandemii (interval de 10-30 ani) • 1889, 1890 → ipoteza ca îmbolnăvirile
determinate de H.influenzae• 1981, 1919 → formă foarte virulentă → peste 20
milioane decese (ideea că nu H.influenzae este responsabil) (Fig.1)
• 1957- gripă asiatică, mortalitate mai redusă, apariţia antibioticelor → reducerea suprainfecţiilor bacteriene (H2N2)
• 1968 – gripă Hong-Kong (H3N2) • 2009 - H1N1(Fig.2)
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Morfologie - ME:
• sferic, 100 nm• pe suprafaţă →
proeminenţe spinoase• rar forme
filamentoase• simetrie helicoidală• învelite• ARN m.c. segmentat medicineworld.org
/.../587966655-Nov-18-2006.html
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Structura particulei virale
1. Ribonucleoproteina (RNP)• ARN mc – 8 segmente • Fiecare segment + subunitate proteică care
se depune direct pe spirala ARN
2. Transcriptaza virală
3. Înveliş viral• Proteina M (de matrice)• Strat lipidic• Peplomere: H, N
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Rolul peplomerelor:
• Clasificarea virusurilor gripale
• Ataşarea de celule (H ataş. de R cel)
• Fuziunea vir. cu celula gazdă
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Structura antigenică
1. Ag interne (solubile): RNP, prot M• Conferă specificitate de tip A, B, C• Induc elaborarea anticorpilor fixatori de
complement → dispar repede, nu au rol protector
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Structura antigenică2. Ag de suprafaţă: H, N
• Conferă specificitate de subtip şi variantă• Anticorpii induşi de H → Ac protectori• Fenomen de variabilitate antigenică
• Var. antigenice minore • Mec genetic: mutaţia
• Var. antigenice majore (salt antigenic)• Mec genetic: reasortare, recombinare
genetică
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Denumirea virusurilor gripale:
Tipul/ locul izolării/nr.de ordine/formula antigenică
Ex. A/Hong Kong/1/68 (H3N2)
- La animale se trece şi gazda
- A/swine/Taiwan/1/70 (H3N2)
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Diagnostic de laborator1. Izolarea şi identificarea virusului:
• Spălătură nazo-faringiană (2-3 zile de boală)• Ou de găină embrionat
• Identificarea tipului şi subtipului prin r. HI
• culturi celule• Identificare prin ECP, fen. hemadsorbţie, HI, IF
2. Dg serologic:• R. Hirst (HI)• Probe perechi de seruri
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Diagnostic de laborator
3. Teste rapide (Fig.3):• Identificarea antigenelor virale
Confirmare prin:• IF• RT-PCR• Cultivare
http://www.who.int/csr/disease/avian_influenza/guidelines/RapidTestInfluenza_web.pdf
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Tratament
• Amantadina (Symmetrel)
• Rimantadina (Flumadine)
• Inhibitori de neuraminidază– Oseltamivir (Tamiflu – Roche)– Zanamivir (Relenza - GSK)
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Source: Moscona, A. (2005). Neuraminidase Inhibitors for Influenza. N Engl J Med 353: 1363-1373
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Profilaxie• Vaccin preparat din variantele circulante
• Nu duce la eradicare
• vacc. inactivate cu formol, adm s.c:– Din V.gripal A (H3N2 + H1N1) şi V.gripal B
• Din componente purificate
• vacc. viu cu virulenţă atenuată:– Mutante TS (stim. IgAs)– Pericol de revenire la virulenţă
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