Abstract

As a prophylactic measure against the threat of avian influenza in the Middle East, 130 healthy birds, representing five orders (Anseriformes, Ciconiiformes, Charadriiformes, Galliformes and Gruiformes) and 11 species were inoculated using a commercially available inactivated H5N2 vaccine. Pre- and post-vaccination titres were determined using hemagglutination inhibition technique toward H5N2 antigen. In addition, five non-vaccinated animals were used as controls throughout the study.

Two doses of the vaccine were administered subcutaneously in all animals: at day 0 and day 30. Serology at day 0 confirmed that all birds were negative prior to inoculation. Post-vaccination antibody titres were subsequently evaluated at day 30 and day 60. Vaccine doses administered were weight dependent: birds with a body weight less than 400 g received a dose of 0.25 ml; birds between 400 g and 2 kg were given 0.5 ml; whereas heavier individuals received 1 ml.

In some species, one dose proved sufficient to produce 100% seroconversion, although the second booster stimulated higher antibody titres. Stone-curlews (Burhinus oedicnemus) were the only species that failed to show good levels of seroconversion. Although the reason for this is not readily apparent, an unidentified immunosuppressive factor(s) is suspected.

Neither adverse reactions to the vaccine employed, nor vaccination-related mortality were reported during our trial.

Although post-vaccination experimental live virus challenge of birds in this study was not possible, one can surmise that the attained titres are protective, owing to the fact that they compare favourably to established protective titres in domestic poultry.