Article

Synergy between avian pneumovirus and Ornithobacterium rhinotracheale in turkeys.

Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Salisburylaan 133, B9820, Merelbeke, Belgium.
Avian Pathology (impact factor: 1.71). 07/2005; 34(3):204-11. DOI:10.1080/03079450500096414 pp.204-11
Source: PubMed

ABSTRACT The purpose of this study was to assess the possible synergism between Ornithobacterium rhinotracheale (ORT) and avian pneumovirus (APV), inoculated into turkeys via the natural route, for the reproduction of respiratory disease. Three-week-old specific pathogen free turkeys were inoculated oculonasally with either APV subtype A, ORT or both agents using two different time intervals (3 and 5 days) between APV and ORT. The birds were observed clinically on a daily basis and swabbed intratracheally at short, regular intervals. They were killed at 1, 3, 5, 8 and 15 days post single or dual inoculation and examined for gross lesions at necropsy. Samples of the turbinates, trachea, lungs, air sacs, heart, pericardium and liver were taken for bacteriological and/or histological examination. Combined APV/ORT infections resulted in overt clinical signs and a longer persistence of ORT in the respiratory tract and aggravated the macroscopic and histological lesions in comparison with the groups given single infections. In all ORT-challenged turkeys, ORT was isolated from the turbinates, trachea and lungs, but in turkeys infected with both agents ORT was frequently found in the air sacs and on a single occasion in the heart and pericardium. The time interval between APV and ORT inoculation did not have a significant effect on the outcome of the dual infection. A conspicuous important feature was the attachment of ORT to the cilia of the epithelium of the turbinates and trachea of both ORT-infected and APV/ORT-infected birds. In conclusion, the results show that ORT is able to adhere to and colonize the respiratory tract but, under the circumstances used in this study, is not capable of inducing respiratory disease without viral priming.

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Keywords

15 days post single
 
5 days
 
agents ORT
 
APV subtype
 
APV/ORT infections
 
APV/ORT-infected birds
 
avian pneumovirus
 
different time intervals
 
dual infection
 
dual inoculation
 
gross lesions
 
histological examination
 
histological lesions
 
ORT inoculation
 
overt clinical signs
 
regular intervals
 
respiratory tract
 
significant effect
 
single infections
 
viral priming