title: Persistence and tissue distribution of infectious bursal disease virus in experimentally infected SPF and commercial broiler chickens.
abstract: This study was initiated to determine the persistence, distribution, and quantification of infectious bursal disease virus (IBDV) in lymphoid and nonlymphoid tissues of specific-pathogen-free (SPF) and commercial broiler chickens. Two serotype 1 strains, STC classic and IN variant, were independently used in the experiments. Five separate experiments were conducted using 2- and 4-wk-old SPF chickens, 2- and 4-wk-old in ovo-vaccinated commercial broilers, and 2-wk-old commercial broilers having maternally derived anti-IBDV antibodies. Pooled data from five experiments revealed that SPF chickens had a significantly higher incidence of IBDV-positive reverse transcriptase PCR (RT-PCR) results than commercial chickens (multivariable logistic regression, adjusted odds ratio = 15.28; 95% confidence limits [CL] = 9.53, 24.51, P < 0.0001). In many cases, the viral RNA (vRNA) persisted longer in in ovo-vaccinated commercial broilers bearing maternally derived antibodies compared with similar broilers not vaccinated in ovo. The STC strain was more frequently detected in tissues than the IN strain (chi-square P < 0.0001). In lymphoid tissues, STC and IN strains were detected for the longest duration in bursal tissues followed by spleen, thymus, and bone marrow. In nonlymphoid tissues, STC and IN strains were detected the longest in cecum followed by liver, kidney, pancreas, lungs, thigh, and breast muscles. Compared with bursal tissues, muscle and bone marrow tissues were significantly less likely to yield an IBDV-positive RT-PCR result (P < 0.0001). Although STC vRNA was detected up to 42 days postinoculation (DPI) in bursal homogenates of SPF chickens, virus isolation from bursal homogenates using embryonated chicken eggs was only possible up to 28 DPI. Similarly, STC vRNA was detected up to 42 DPI in bursal tissues of commercial broilers, but infectious virus could be isolated only up to 21 DPI. The IN strain was isolated up to 10 DPI from bursal homogenates of SPF chickens and broilers, but vRNA was detected up to 35 DPI in SPF chickens and 21 DPI in broilers. This study emphasizes that the detection ofvRNA is not indicative of the presence of infectious virus, and virus isolation has to be performed to prove the presence of infectious virus.
authors.affiliation: Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, USA.
authors.forename: Rauf
authors.initials: R
authors.lastname: Abdul
authors.affiliation: Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, USA.
authors.forename: Maria V
authors.initials: MV
authors.lastname: Murgia
authors.affiliation: Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Rodriguez-Palacios
authors.affiliation: Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, USA.
authors.forename: Chang-Won
authors.initials: CW
authors.lastname: Lee
authors.affiliation: Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, USA.
authors.forename: Yehia M
authors.initials: YM
authors.lastname: Saif
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D018175:Birnaviridae Infections / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D002642:Chick Embryo; D002645:Chickens; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D007112:Immunity, Maternally-Acquired; D015994:Incidence; D007243:Infectious bursal disease virus / Q000145:classification / Q000235:genetics / Q000276:immunology*; D011201:Poultry Diseases / Q000453:epidemiology / Q000276:immunology* / Q000517:prevention & control; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D013047:Specific Pathogen-Free Organisms
chemical_list: D000914:Antibodies, Viral; D012367:RNA, Viral