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    Isolation of highly pathogenic avian influenza H5N1 from table eggs after vaccinal break in commercial layer flock (2010)

    Art
    Zeitschriftenartikel / wissenschaftlicher Beitrag
    Autoren
    Kilany, W. H.
    Arafa, A.
    Erfan, A. M.
    Ahmed, M. S.
    Nawar, A. A.
    Selim, A. A.
    Khoulosy, S. G.
    Hassan, M. K.
    Aly, M. M.
    Hafez, H. M.
    Abdelwhab, E. M.
    Quelle
    Avian diseases; 54(3) — S. 1115–1119
    ISSN: 0005-2086
    Sprache
    Englisch
    Verweise
    Pubmed: 20945800
    Kontakt
    Institut für Geflügelkrankheiten

    Königsweg 63
    14163 Berlin
    +49 30 838 62676
    gefluegelkrankheiten@vetmed.fu-berlin

    Abstract / Zusammenfassung

    In May 2009, during routine monitoring of a commercial layer flock of about 87,000 birds kept in cages in 4 different houses that had been vaccinated 3 times with an inactivated H5N1 vaccine at weeks 1, 7, and 16, highly pathogenic avian influenza (HPAI) virus of subtype H5N1 was isolated and detected by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) in tracheal and cloacal swabs collected from houses 3 and 4; 7 days after onset of clinical signs, there was an increase in mortality accompanied by a decrease in egg production and egg quality. In addition, using RT-PCR, the viral RNA could be detected from albumin and eggshell as well. Seven days after the onset of the clinical signs, the hemagglutination inhibition (HI) titers in the affected houses were 3.2 and 1.9 log2. In the other two houses, there were no clinical signs, and all tested samples were negative using virus isolation and real-time RT-PCR. The HI titers were 6.6 and 7.0 log2 in nonaffected houses. The isolated virus from egg albumin showed high nucleotides and amino-acid identities and clustered with viruses from recently H5N1-confirmed human infections and poultry from different places in Egypt. Moreover, several amino-acid substitutions of viral H5 protein were observed. The vaccinal break seems to be associated with immune escape mutants and/or improper vaccination. The role of contaminated eggs as a source of infection and as a vehicle for spread of the virus should be considered in area with avian influenza outbreaks.