Dynamics Of Antibody Against Duck Hepatitis Virus In Breed Ducks And Of Maternal Antibody In Ducklings

Duck viral hepatitis (DHV) caned by duck hepatitis virus-I is highly mottal disease and spread rapidly in ducks, and has become onc of the most inpoilant diseases which freaten duck h2dwtzy recently. DHV-I mainly infects one-month-old ducldings especially two-week-old ducldings. In this researeh, Vmis stmin-Nobilis Duck Hepatitis (stanunE.53) was wed to immunize breed ducks, and the duddings acquired natural passive inununity Semlogical diagnostic methods e wed to detect the I)HV-I antibody level of ducks and diddings, mid study the alternation of DH V-I antibody. 9-day-old nornmmunized duck emb.s e used to propagate DHV-lafter injection of vinzs ,the dead embryos caused by DHV-I are broken into pieces, supeinatant of homogenized tissue was prepared as the antigen of neutralization tesis,The virus purified by deducting fat with cblomfonn concentrated with PEG and diflbreniial cenlrifiigalion was prepared as the antigen of complement fixation te~ Nwblizaticm test was used to detect the dynamics of antibody in immunized ducks and maternal antibody in ducklings. 11~ results suggested that no antibody was detected within the 4 weeks after the fli~ nmimizatiom, until fr first week after the second innnunization, the neutralization antibody was detected aid the titer wasl.15 1g. The antibody titer was 2.28 lg at thefoutlhweekaftuthesecond and280lgatfrlburdiweekafterfrthiiti immunization. 11~ antibody of duddings at one-day-old was 2281g. and decreased to 1.54 Ig at sevendaysold. Theantibodytiterofduddinpat l4dayswas 1.44 lganddecreasedto 1.00 Igat 19 days old. The complement fixation test was firstly applied to detect anti-DHV antibody. Complement fixation antibody can be detected at two weeks after the first immunization, and antibody titer was 1.67 logs anU1~ody titer increased to 4.67 log2 at 17 days after the second immtmization; and died to 7.17 log2 at fore weeks after the third immunization. 11~ results demonstrated that complement fixation test not suitable fbr antibody detection of ducklings. The comnparision of the results of neutralization test with complement fixation test indicated that the altanatiom of antibody titer were parallel, but the detection of complement fixation antibody is earlier than tlut of neutralization antibody. The results in this research indicated: When antibody titer of duddings was between 228 ig aid 1.44 lg ,the duckling can completely iesistto challenge of virulent sbin-161/79/V(EID~l.OO0). MtediySdue MajorProf. Wang Jun wei...