Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/27470
Title: Uptake and spread of infectious laryngotracheitis vaccine virus within meat chicken flocks following drinking water vaccination
Contributor(s): Groves, Peter J  (author); Williamson, Sarah L (author); Sharpe, Sue M (author); Gerber, Priscilla F  (author)orcid ; Gao, Yuanshuo K (author); Hirn, Tabitha J (author); Walkden-Brown, Stephen W  (author)orcid 
Publication Date: 2019-08-14
Early Online Version: 2019-07-09
DOI: 10.1016/j.vaccine.2019.06.087
Handle Link: https://hdl.handle.net/1959.11/27470
Abstract: 

Vaccination against infectious laryngotracheitis virus (ILTV) in commercial broiler flocks in the field, which is only undertaken in the face of a local outbreak, requires mass administration techniques, usually via drinking water. This is often fraught with difficulties such as variable vaccination "reactions" and sometimes, vaccination failure. Laboratory testing of the outbreak strains however invariably shows the vaccines in use to be protective. To investigate this paradox, the dynamics of an ILT vaccine virus was examined within broiler flocks during a natural outbreak. In an initial flock, 70 birds were individually identified and had tracheal swabs collected sequentially at intervals from 1 to 26 days after vaccination and submitted for ILTV detection using qPCR. This evaluation was extended by collection of tracheal swabs from 40 to 45 random birds at 4, 7-8, 12-13 and 25-26 days post vaccination (pv) across a further 7 flocks. The results showed a very variable early uptake of vaccine virus from the drinking water (between 3% and 52% of tested birds with detectable virus in trachea at 4 days pv) and revealed that actual vaccination of the flocks relied on bird to bird transmission of the vaccine virus. In flocks with very low (<10%) initial bird uptake, successful exposure of vaccine virus to the majority of the flock can be delayed, leaving a large proportion of birds as susceptible at the likely time of possible exposure to wild virus. This may explain the cases of apparent failure of vaccination in the field. The variable bird to bird spread can be associated with reversion to virulence, this may explain the rolling vaccine reactions often observed. The variation in initial vaccine uptake may be affected by some factors involved with the administration technique and this requires further study in a larger sample size.

Publication Type: Journal Article
Source of Publication: Vaccine, 37(35), p. 5035-5043
Publisher: Elsevier Ltd
Place of Publication: United Kingdom
ISSN: 1873-2518
0264-410X
Fields of Research (FoR) 2008: 070712 Veterinary Virology
Fields of Research (FoR) 2020: 300914 Veterinary virology
300304 Animal protection (incl. pests and pathogens)
300905 Veterinary epidemiology
Socio-Economic Objective (SEO) 2008: 830309 Poultry
Socio-Economic Objective (SEO) 2020: 100411 Poultry
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
Appears in Collections:Journal Article
School of Environmental and Rural Science

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