DETERMINATION OF ANTIBODY LEVEL PROTECTIN G AGAINST DERZSYS-DISEASE IN DAY-OLD AND 8-DAY-OLD SPF GOSLINGS

Since information in bibliography is insufficient and it is based main ly on epidemiologic observation, the aim of this study is to determine in the blood of day-old goslings as well as in Derzsy's disease antis erum the VN titers which afford full protection. Each of SPF goslings allotted into three groups was given 2 ml antiserum subcutaneously wit hin 4 hours after hatching. Titer of: the antiserum given to group 1 a mounted to 1:750, those for group 2 and group 3 were 1:500 and 1:250, respectively. VN titers of blood samples were determined 24 hours post inoculationem and weekly for 4 weeks. Each of the groups were divided in two and challenge-infected with 0.5 ml of virulent virus Derzsy B (the challenge dose contained 478.6 LD50 for day old goslings and 213. 8 LD50 respectively for 8-day-old goslings) by the intraperitoneal rou te on day 1 and day 8 (Table 2). Birds injected with so-called negativ e serum (VN titer <2) which were challenged as well as uninjected and unchallenged birds served as controls. It has been found (Table 1) tha t in the blood of goslings VN titer of 1:34 at day old or a VN titer o f over 1:24 at 8 days old were safe, however a titer under 1:16 afford ed partial protection against a challenge-infection with virulent viru s. These protective titers were found in goslings after the treatment with 1:500 titered serum and particularly with 1:750 titered serum. Dy namics of antiserum decay is shown in Figure 1, the weight gain of bir ds challenged on day 1 and day 8, respectively and the weight gain of control birds are shown in Figures 2, 3, 4 and 5. The VN titer of 1:52 at day old afforded by a treatment with an antiserum of VN titer 1:75 0 which complies with specification proved to be safely sufficient for protecting birds from clinical signs of Derzsy's disease.