Molecular and serological dynamics of Chlamydia pecorum infection in a longitudinal study of prime lamb production

Bommana, S; Walker, E; Desclozeaux, M; Jelocnik, M; Timms, P; Polkinghorne, A; Carver, S

Molecular and serological dynamics of Chlamydia pecorum infection in a longitudinal study of prime lamb production

Bommana, S Walker, E Desclozeaux, M Jelocnik, M

Timms, P Polkinghorne, A Carver, S

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Publication Type:: Journal Article
Citation:: PeerJ, 2018, 2018 (1)
Issue Date:: 2018-01-01

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Field	Value	Language
dc.contributor.author	Bommana, S	en_US
dc.contributor.author	Walker, E	en_US
dc.contributor.author	Desclozeaux, M	en_US
dc.contributor.author	Jelocnik, M https://orcid.org/0000-0003-1340-2562	en_US
dc.contributor.author	Timms, P	en_US
dc.contributor.author	Polkinghorne, A	en_US
dc.contributor.author	Carver, S	en_US
dc.date.available	2018-01-06	en_US
dc.date.issued	2018-01-01	en_US
dc.identifier.citation	PeerJ, 2018, 2018 (1)	en_US
dc.identifier.uri	http://hdl.handle.net/10453/130707
dc.description.abstract	© 2018 Bommana et al. Background. Chlamydia pecorum is a globally significant livestock pathogen causing pathology and production losses. The on-farm infection and serological dynamics and the relevance of existing diagnostic tools for diagnosing C. pecorum in livestock remains poorly characterized. In this study, we characterized the antigen and antibody dynamics of this pathogen in a longitudinal study of prime lamb production, utilizing the infection focused C. pecorum-specific 16S rRNA qPCR assay and serology based chlamydial Complement fixation Test (CFT). Methods. The study consisted of 76 Border Leicester mixed sex lambs (39 females and 37 males) that were sampled bimonthly from 2-10 months of age in a commercial farm operating in Central NSW, Australia. Blood/plasma was analysed for CFT antibodies, and swabs from conjunctival, rectal and vaginal sites were analysed for C. pecorum shedding using qPCR. We assessed the temporal and overall dynamics of C. pecorum in lambs, including detailed description and comparison of qPCR and CFT, the timing of first detection by either diagnostic method, the lag between infection and antibody response; and the distribution of qPCR load and CFT antibody titre over time. Results. Over the study period, C. pecorum was highly prevalent (71.0% by qPCR, 92.1% by CFT, 96.0% by both), with 21.1% (16/76) lambs shedding ≥1;000 qPCR copies/ml (denoted as high shedders). C. pecorum shedding (as evidence of infection) were first observed at two months of age (14.4%) with a significant peak of infection occurring at six months of age (34.2%), whereas seroconversions peaked at eight months of age (81.5%). 52.6% of C. pecorum qPCR and CFT positive lambs became qPCR negative by 10 months of age, indicating clearance of chlamydial infection. Although CFT is utilised for on-farm detection of active infection, we confirm that it lagged behind qPCR detection (average lag 1.7 ± 2.1 months) and that the proportion of qPCR positives simultaneously identified by CFT was low with 2/11 (18.1%), 0/13, 17/25 (68.0%), 5/7 (71.4%) and 1/10 (10.0%) concurrent seroconversions occurring at two, four, six, eight and 10 months of age, respectively. Discussion. This work reveals rapid rates of C. pecorum infection and widespread exposure during lamb production. The comparison of molecular and serological diagnostic agreement longitudinally, supports the use of qPCR as an important ancillary tool for the detection of active infections in conjunction with chlamydial CFT for routine veterinary diagnostics. Development of rapid Point-of-Care (POC) tools for diagnosing active infection would be valuable for producers and veterinarians.	en_US
dc.relation.ispartof	PeerJ	en_US
dc.relation.isbasedon	10.7717/peerj.4296	en_US
dc.title	Molecular and serological dynamics of Chlamydia pecorum infection in a longitudinal study of prime lamb production	en_US
dc.type	Journal Article
utslib.citation.volume	1	en_US
utslib.citation.volume	2018	en_US
utslib.for	0605 Microbiology	en_US
utslib.for	0702 Animal Production	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
utslib.copyright.status	open_access
pubs.issue	1	en_US
pubs.publication-status	Published	en_US
pubs.volume	2018	en_US

Abstract:

© 2018 Bommana et al. Background. Chlamydia pecorum is a globally significant livestock pathogen causing pathology and production losses. The on-farm infection and serological dynamics and the relevance of existing diagnostic tools for diagnosing C. pecorum in livestock remains poorly characterized. In this study, we characterized the antigen and antibody dynamics of this pathogen in a longitudinal study of prime lamb production, utilizing the infection focused C. pecorum-specific 16S rRNA qPCR assay and serology based chlamydial Complement fixation Test (CFT). Methods. The study consisted of 76 Border Leicester mixed sex lambs (39 females and 37 males) that were sampled bimonthly from 2-10 months of age in a commercial farm operating in Central NSW, Australia. Blood/plasma was analysed for CFT antibodies, and swabs from conjunctival, rectal and vaginal sites were analysed for C. pecorum shedding using qPCR. We assessed the temporal and overall dynamics of C. pecorum in lambs, including detailed description and comparison of qPCR and CFT, the timing of first detection by either diagnostic method, the lag between infection and antibody response; and the distribution of qPCR load and CFT antibody titre over time. Results. Over the study period, C. pecorum was highly prevalent (71.0% by qPCR, 92.1% by CFT, 96.0% by both), with 21.1% (16/76) lambs shedding ≥1;000 qPCR copies/ml (denoted as high shedders). C. pecorum shedding (as evidence of infection) were first observed at two months of age (14.4%) with a significant peak of infection occurring at six months of age (34.2%), whereas seroconversions peaked at eight months of age (81.5%). 52.6% of C. pecorum qPCR and CFT positive lambs became qPCR negative by 10 months of age, indicating clearance of chlamydial infection. Although CFT is utilised for on-farm detection of active infection, we confirm that it lagged behind qPCR detection (average lag 1.7 ± 2.1 months) and that the proportion of qPCR positives simultaneously identified by CFT was low with 2/11 (18.1%), 0/13, 17/25 (68.0%), 5/7 (71.4%) and 1/10 (10.0%) concurrent seroconversions occurring at two, four, six, eight and 10 months of age, respectively. Discussion. This work reveals rapid rates of C. pecorum infection and widespread exposure during lamb production. The comparison of molecular and serological diagnostic agreement longitudinally, supports the use of qPCR as an important ancillary tool for the detection of active infections in conjunction with chlamydial CFT for routine veterinary diagnostics. Development of rapid Point-of-Care (POC) tools for diagnosing active infection would be valuable for producers and veterinarians.

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http://hdl.handle.net/10453/130707