Airborne Transmission of Vaccinal and Wild Type Infectious Laryngotracheitis Virus and Noninfectivity of Extracts of Excreta from Infected Chickens

Title
Airborne Transmission of Vaccinal and Wild Type Infectious Laryngotracheitis Virus and Noninfectivity of Extracts of Excreta from Infected Chickens
Publication Date
2021-03
Author(s)
Yegoraw, Addisu Awukew
Nazir, Shahid
Gerber, Priscilla F
( author )
OrcID: https://orcid.org/0000-0002-8343-8299
Email: pgerber2@une.edu.au
UNE Id une-id:pgerber2
Walkden-Brown, Stephen W
( author )
OrcID: https://orcid.org/0000-0002-0638-5533
Email: swalkden@une.edu.au
UNE Id une-id:swalkden
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
American Association of Avian Pathologists, Inc
Place of publication
United States of America
DOI
10.1637/aviandiseases-D-20-00073
UNE publication id
une:1959.11/51880
Abstract

Infectious laryngotracheitis virus (ILTV) is thought to exit the host in respiratory aerosols and enter by inhalation of these. High levels of ILTV DNA have been detected in excreta, raising the possibility of alternative routes of shedding from the host. However, it is not known whether or not the ILTV DNA in excreta represents infective virus. This study investigated transmission of wild type and vaccinal ILTV from infected to susceptible commercial meat chickens. Airborne- and excreta-mediated transmission of two field isolates of ILTV (Classes 9 and 10) and three vaccine strains (SA2, A20, and Serva) were tested. To test airborne transmission, air from isolators containing infected birds was ducted through a paired isolator containing uninfected chickens. To test excreta transmission, aliquots were prepared from excreta containing a high level of ILTV DNA within the first week after infection. Chicks were infected bilaterally by eye drop. Clinical signs were monitored daily and choanal cleft swab samples for ILTV detection by quantitative PCR were collected at 4, 8, 15, 22, and 28 days postinfection (DPI) in the airborne transmission study and at 7 and 14 DPI from the excreta transmission studies. There was no transmission of ILTV from excreta, suggesting that ILTV is inactivated during passage through the gut. All strains of ILTV were transmitted by the airborne route but only to a limited extent for the vaccine viruses. The field viruses induced clinical signs, pathology, and greatly elevated ILTV genome copies in swabs. In summary, these findings confirm the suspected airborne transmission of ILTV, demonstrate differential transmission potential between wild type and vaccine strains by this route, and indicate that excreta is unlikely to be important in the transmission of ILTV and the epidemiology of ILT.

Link
Citation
Avian Diseases, 65(1), p. 30-39
ISSN
1938-4351
0005-2086
Pubmed ID
34339119
Start page
30
End page
39

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