Attenuation and protection efficacy of ORF C gene-deleted recombinant of infectious laryngotracheitis virus.
Infectious laryngotracheitis (ILT) is a highly contagious respiratory disease of chickens caused by infectious laryngotracheitis virus (ILTV). The disease is controlled by the use of live-attenuated vaccines. Previously we reported the complete nucleotide sequence of the ILTV vaccine strain (TCO) and identified a nonsense mutation in the gene encoding the ORF C protein. This suggested that the ORF C protein might be associated with viral virulence. To investigate this, an ILTV recombinant with a deletion in the gene encoding ORF C was constructed using the genome of the virulent United States Department of Agriculture (USDA) challenge strain (USDAch). Compared to the parental virus, the ΔORF C recombinant replicated in chicken kidney (CK) cells with similar kinetics and generated similar titres. This demonstrated that the ORF C deletion had no deleterious effects on replication efficacy in vitro. In chickens, the recombinant induced only minor microscopic tracheal lesions when inoculated via the intra-tracheal/ocular route, while the parental strain induced moderate to severe microscopic tracheal lesions, even though virus load in the tracheas were comparable. Groups of chickens vaccinated via eye-drop with the ∆ORFC-ILTV were protected to levels comparable to those elicited by TCO vaccination. To our knowledge, this is the first report that demonstrates the suitability of ∆ORFC as a live-attenuated vaccine to prevent the losses caused by ILTV.
Poultry Diagnostic and Research Center, Department of Population Health, College of Veterinary Medicine, University of Georgia, 953 College Station Rd, Athens, GA 30602, USA.
Maricarmen
M
Garcia
US National Poultry Research Center, Agricultural Research Service, United States Department of Agriculture, 934 College Station Rd, Athens, GA 30602, USA.
S J
SJ
Spatz
Poultry Diagnostic and Research Center, Department of Population Health, College of Veterinary Medicine, University of Georgia, 953 College Station Rd, Athens, GA 30602, USA.|US National Poultry Research Center, Agricultural Research Service, United States Department of Agriculture, 934 College Station Rd, Athens, GA 30602, USA.
Y
Y
Cheng
Poultry Diagnostic and Research Center, Department of Population Health, College of Veterinary Medicine, University of Georgia, 953 College Station Rd, Athens, GA 30602, USA.
S M
SM
Riblet
BASE2BIO, 3461 Wayne Street, Madison, WI 53714, USA.
J D
JD
Volkening
Poultry Diagnostic and Research Center, Department of Population Health, College of Veterinary Medicine, University of Georgia, 953 College Station Rd, Athens, GA 30602, USA.
G H
GH
Schneiders
D000818:Animals; D002460:Cell Line; D002645:Chickens; D017353:Gene Deletion; D005814:Genes, Viral; D006566:Herpesviridae Infections / Q000473:pathology / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D025921:Iltovirus / Q000235:genetics* / Q000276:immunology* / Q000472:pathogenicity / Q000502:physiology; D011201:Poultry Diseases / Q000473:pathology / Q000517:prevention & control* / Q000821:virology; D014132:Trachea / Q000473:pathology; D016896:Treatment Outcome; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D019562:Viral Load; D014765:Viral Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D037521:Virulence Factors / Q000235:genetics*; D014779:Virus Replication
D014613:Vaccines, Attenuated; D014614:Vaccines, Synthetic; D014765:Viral Vaccines; D037521:Virulence Factors