title: Continued use of IBV 793B vaccine needs reassessment after its withdrawal led to the genotype's disappearance.
abstract: Over a period of almost two years, broilers chickens on several hundred Italian farms, were monitored for infectious bronchitis virus. Detections were genotyped using a hypervariable region of the gene coding for the S1 segment of the spike protein. A range of genotypes were detected which comprised QX, Q1, Mass, D274 and 793B. Sequences of 793B viruses detected in chickens, vaccinated with either of the two commonly used 793B type vaccines were almost identical to sequences of one or other of these vaccines. This strong indication of vaccine association led to the withdrawal of live 793B vaccine use on all of the farms of the study. Except for one sample collected soon after 793B vaccination ceased, it was no longer possible to detect 793B vaccine on these farms. It appears that field 793B strains have disappeared from the region of Italy tested thus obviating any need for current vaccine protection against 793B.
authors.affiliation: Department of Animal Medicine, Production and Health, University of Padua, Viale dell'università, 16, 35020 Legnaro, PD, Italy. Electronic address: giovanni.franzo@studenti.unipd.it.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Franzo
authors.affiliation: Department of Infection Biology, Faculty of Health and Life Sciences, University of Liverpool, Leahurst Campus, Neston CH64 7TE, United Kingdom.
authors.forename: Clive John
authors.initials: CJ
authors.lastname: Naylor
authors.affiliation: Department of Veterinary Medical Sciences - University of Bologna, Via Tolara di Sopra, 50, 40064 Ozzano Emilia, BO, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Lupini
authors.affiliation: Department of Animal Medicine, Production and Health, University of Padua, Viale dell'università, 16, 35020 Legnaro, PD, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Drigo
authors.affiliation: Department of Veterinary Medical Sciences - University of Bologna, Via Tolara di Sopra, 50, 40064 Ozzano Emilia, BO, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Catelli
authors.affiliation: Department of Veterinary Medical Sciences - University of Bologna, Via Tolara di Sopra, 50, 40064 Ozzano Emilia, BO, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Listorti
authors.affiliation: Tre Valli Laboratory, Viale A. Veronesi, 5, 37132 San Michele Extra, VR, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Pesente
authors.affiliation: Tre Valli Laboratory, Viale A. Veronesi, 5, 37132 San Michele Extra, VR, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Giovanardi
authors.affiliation: Field veterinary, 37026, Pescantina, VR, Italy.
authors.forename: Emilio
authors.initials: E
authors.lastname: Morandini
authors.affiliation: Department of Animal Medicine, Production and Health, University of Padua, Viale dell'università, 16, 35020 Legnaro, PD, Italy.
authors.forename: Mattia
authors.initials: M
authors.lastname: Cecchinato
mesh_terms: D000818:Animals; D002645:Chickens; D018352:Coronavirus Infections / Q000453:epidemiology / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D005838:Genotype; D001351:Infectious bronchitis virus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D007558:Italy / Q000453:epidemiology; D011201:Poultry Diseases / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology*; D057051:Product Recalls and Withdrawals; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology; D014765:Viral Vaccines / Q000008:administration & dosage* / Q000276:immunology*
chemical_list: D014613:Vaccines, Attenuated; D014765:Viral Vaccines
keywords: 793B genotype disappeared; 793B vaccination discontinued; Broiler farm survey; Infectious bronchitis virus; S1 sequence