engleski

Chicken protection against infectious bursal disease virus by inactivated water-in-oil-in-water vaccine

Background and Aims: The incidence of a IBDV in Croatia in 1995 seems to be a natural consequence of the global spread and resulted in up to 60% and 20% mortality of laying hens and broilers, respectively. Vaccination of a parent stock with a live vaccine and revaccination with an inactivated vaccine at the point-of-lay in order to ensure transfer of maternal antibodies (MN-Abs) to the progeny, was proposed as a prophylactic measure. For this purpose, an inactivated vaccine, adjuvanted by a multiple water-in-oil-in-water emulsion (WOWE) of a low viscosity, was designed. The IBDV-WOWE was tested in order to determine its ability for eliciting a levels of specific Abs in parents which should result in an improved progeny protection. Methods: Winterfield 2512 strain of IBDV, inactivated with 0.1% v/v formaldehyde, was prepared in a WOWE. The WOWE contained 3.3% w/v of both aqueous- (Tween 80) and oil-phase surfactants (Aralcel 83) and a low quality of mineral oil (30% v/v). The aqueos/oil ratio (2/1) and hydrophile-lipophile balance (HLB = 9.35) were high, while the relative viscosity (n = 3.45) was low. Flocks of 4500 light ISA Brown SSL layers and 2400 heavy Hybro breeders, aged 10 days, were vaccinated by a live IBDV (Gumbokal, Pliva, Zagreb, Croatia) vaccine in drinking water. Trials were carried out under field conditions. Light pullets aged 19 weeks and heavy pullets aged 18 weeks, were both divided in three equal groups and i.m. vaccinated with 1.0, 0.5 and 0.25 ml vaccine/bird. Serological response (ELISA-titers) was monitored during the whole laying period. The eggs, collected 31 weeks after vaccination of dams, were hatched. Sera from 3- and 10-day-old hatched chickens were analysed for the presence of MN-Abs. Results and Conclusion: A WOWE contributes to the stability, low viscosity and injectability of the IBDV vaccine without side-effects. Serological responses in both light and heavy breaders, were directly related to the doses of the vaccine administered. A single vaccination generated high and a long-lasting humoral immunity and no additional vaccinations were required during the laying period. The vaccination with the IBDV-WOWE vaccine had no influence on the egg production. The levels of specific Abs in the egg yolks were at least twice higher than those in the sera of the vaccinated dams. The anti-IBDV antibodies were transferred to progeny. The ELISA-titer of the MN-Abs in the sera of 3-day-old offspring was about 2800 and decreased till the 10th day of life.

chickens; infectious bursal disease; breeders; water-in-oil-in-water vaccine; passive protection

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