title: Recombinant infectious bronchitis coronavirus Beaudette with the spike protein gene of the pathogenic M41 strain remains attenuated but induces protective immunity.
abstract: We have replaced the ectodomain of the spike (S) protein of the Beaudette strain (Beau-R; apathogenic for Gallus domesticus chickens) of avian infectious bronchitis coronavirus (IBV) with that from the pathogenic M41 strain to produce recombinant IBV BeauR-M41(S). We have previously shown that this changed the tropism of the virus in vitro (R. Casais, B. Dove, D. Cavanagh, and P. Britton, J. Virol. 77:9084-9089, 2003). Herein we have assessed the pathogenicity and immunogenicity of BeauR-M41(S). There were no consistent differences in pathogenicity between the recombinant BeauR-M41(S) and its apathogenic parent Beau-R (based on snicking, nasal discharge, wheezing, watery eyes, rales, and ciliostasis in trachea), and both replicated poorly in trachea and nose compared to M41; the S protein from the pathogenic M41 had not altered the apathogenic nature of Beau-R. Both Beau-R and BeauR-M41(S) induced protection against challenge with M41 as assessed by absence of recovery of challenge virus and nasal exudate. With regard to snicking and ciliostasis, BeauR-M41(S) induced greater protection (seven out of nine chicks [77%]; assessed by ciliostasis) than Beau-R (one out of nine; 11%) but less than M41 (100%). The greater protection induced by BeauR-M41(S) against M41 may be related to the ectodomain of the spike protein of Beau-R differing from that of M41 by 4.1%; a small number of epitopes on the S protein may play a disproportionate role in the induction of immunity. The results are promising for the prospects of S-gene exchange for IBV vaccine development.
authors.affiliation: Institute for Animal Health, Division of Molecular Biology, Compton Laboratory, Compton, Newbury, Berkshire, RG20 7NN United Kingdom.
authors.forename: Teri
authors.initials: T
authors.lastname: Hodgson
authors.forename: Rosa
authors.initials: R
authors.lastname: Casais
authors.forename: Brian
authors.initials: B
authors.lastname: Dove
authors.forename: Paul
authors.initials: P
authors.lastname: Britton
authors.forename: Dave
authors.initials: D
authors.lastname: Cavanagh
mesh_terms: D000818:Animals; D002645:Chickens; D018352:Coronavirus Infections / Q000473:pathology / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D001351:Infectious bronchitis virus / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology*; D009924:Organ Culture Techniques; D011201:Poultry Diseases / Q000473:pathology / Q000517:prevention & control* / Q000821:virology; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology*; D064370:Spike Glycoprotein, Coronavirus; D014132:Trachea / Q000473:pathology / Q000821:virology; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology*; D014779:Virus Replication
chemical_list: D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus