Comparative Impact of Live Chicken Infectious Anaemia VirusVaccine versus Natural Exposure in Meat Chicken Breeders on Immunity to Infectivity by CIA and Inclusion BodyHepatitisVirusesinTheirO¡spring E.K. Barbour 1 *,M.T.Farran 1 ,S.K.Hamadeh 1 ,M.Bouljihad 2 ,O.Faroon 3 and S. Kreydiyyeh 4 1 Departmentof Animal Science, Faculty of Agricultural and Food Sciences, American University of Beirut, Beirut, Lebanon; 2 Veterinary Diagnostic Laboratory, School of Veterinary Medicine, University of Minnesota, St Paul, Minnesota; 3 United States Public Health Service, Centers for Disease Control, Atlanta, Georgia, USA; 4 Biology Department, American University of Beirut, Beirut, Lebanon *Correspondence:Tigah Kanisat Martakla, Sahat Alayn, Kafarchima, Lebanon Barbour, E.K., Farran, M.T., Hamadeh, S.K., Bouljihad, M., Faroon, O. and Kreydiyyeh, S., 2002. Comparative impact of live chicken infectious anaemia virus vaccine versus natural exposure in meat chickenbreedersonimmunitytoinfectivitybyCIAandinclusionbodyhepatitisvirusesintheiro¡spring. Veterinary Research Communications, 26(5),397^405 ABSTRACT The immunology and histopathology and the distribution of viral antigen in infections with chicken infectious anaemia virus (CIAV) and inclusion body hepatitis virus (IBHV) were compared in the broiler o¡spring of CIAV-vaccinated meat chicken breeders versus those in the o¡spring of breeders naturally exposed to ¢eld CIAV. No signi¢cant di¡erence in the humoral antibody level speci¢c for CIAVwasobservedbetween5and33weeksofageinthetwobreedergroups( p40.05).Thematernal humoralimmunitytoCIAVintheday-oldo¡springofthegroupsdidnotdi¡ersigni¢cantly( p40.05). ThehumoralimmunitytoCIAVat40daysofageindicatedanabsenceofclinicalsignsofCIAVinthe broilero¡springofbothgroupsofbreedersandthiswasassociatedwithmeanserumthymulinlevelsin o¡spring of both groups not di¡ering signi¢cantly at 1 or 40 days of age. Histopathological and immuno£uorescence observations did not di¡er signi¢cantly in the o¡spring ofeither group by CIAV orIBHV. Keywords: breeders, chicken infectious anaemia virus, epidemiology, immunity, inclusion body hepatitisvirus,infection,o¡spring,poultry,thymulin,vaccine Abbreviations: CIA, chicken infectious anaemia; CIAV, CIA virus; IBH, inclusion body hepatitis; IBHV,IBHvirus;OD,opticaldensity;PBS,phosphate-bu¡eredsaline;S/N,sample-to-negativeratio INTRODUCTION Inclusion body hepatitis (IBH), caused by infection with a group 1 adenovirus, is a diseasecharacterizedbymortalityapproaching10%(McFerran,1997).IBHisusually observedinchickensbetween3and4weeksofage(McFerran,1991).Researchreports arecontradictoryregardingtheaetiologyofIBH,assomebelievethatadenovirusesare VeterinaryResearchCommunications,26(2002)397^405 # 2002KluwerAcademicPublishers.PrintedintheNetherlands 397