title: Interference between mild and pathogenic strains of infectious bursal disease virus in chickens.
abstract: Infectious bursal disease virus is a contagious, immunosuppressive disease of young chickens that is controlled by vaccination. Cross-protection occurs between different strains of the virus as a result of shared neutralizing epitopes. However, interactions between two antigenically similar strains (a mild and a pathogenic) coinfecting the same host have not been investigated. Groups of specific-pathogen-free chickens were inoculated with a mild strain followed by a pathogenic strain at 0, 16, 24, or 48 hr postinoculation (PI) with a mild strain. Virus persistence and the predominant strain of the virus were determined by reverse transcriptase-polymerase chain reaction and restriction fragment length polymorphism analysis, respectively, in bursas at 2, 4, 8, 14, and 21 days PI with the pathogenic strain. Severity of infection was assessed by the bursa/body weight ratios and histopathologic lesion scores. The mild virus interfered with replication of the pathogenic virus. The greatest interference was observed when the pathogenic strain was inoculated 24 hr PI with the mild strain. The interference phenomenon observed might be due to competition for host receptor sites or production of cytokine(s). This interference phenomenon could have practical implications for vaccine usage and protection.
authors.affiliation: Food Animal Health Research Program, Department of Veterinary Preventive Medicine, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, USA.
authors.forename: S
authors.initials: S
authors.lastname: Ashraf
authors.forename: G
authors.initials: G
authors.lastname: Abdel-Alim
authors.forename: M Q
authors.initials: MQ
authors.lastname: Al-Natour
authors.forename: Y M
authors.initials: YM
authors.lastname: Saif
mesh_terms: D000818:Animals; D018175:Birnaviridae Infections / Q000503:physiopathology / Q000662:veterinary*; D002060:Bursa of Fabricius / Q000821:virology; D002645:Chickens; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D007243:Infectious bursal disease virus / Q000235:genetics* / Q000472:pathogenicity; D012150:Polymorphism, Restriction Fragment Length; D011201:Poultry Diseases / Q000503:physiopathology* / Q000821:virology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D013045:Species Specificity; D013047:Specific Pathogen-Free Organisms; D014762:Viral Interference