Early detection and differential serodiagnosis of Mycoplasma hyorhinis and Mycoplasma hyosynoviae infections under experimental conditions.

Luis G Giménez-Lirola,Ronaldo L Magtoto,David H Baum,Rachel J Derscheid,Igor R H Gatto,Bailey L Arruda,Franco S Matias Ferreyra,Jeffrey J Zimmerman,Paulo H E Arruda,Aric J Mcdaniel,Kent J Schwartz,Richard F Ross,Henrique Meiroz-De-Souza-Almeida,Maria M Merodio,Korakrit Poonsuk,Simon Russell Clegg

doi:10.1371/journal.pone.0223459

Luis G Giménez-Lirola, Ronaldo L Magtoto + Show 14 more

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https://doi.org/10.1371/journal.pone.0223459

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Abstract

Mycoplasma hyorhinis (MHR) and Mycoplasma hyosynoviae (MHS) are common opportunistic pathogens in the upper respiratory tract and tonsils of swine. The identification of the specific species involved in clinical cases using conventional diagnostic methods is challenging. Therefore, a recombinant chimeric polypeptide based on the seven known variable lipoproteins (A-G) specific of MHR and a cocktail of surface proteins detergent-extracted from MHS cultures were generated and their suitability as antemortem biomarkers for serodiagnosis of MHR- and MHS-infection were evaluated by ELISA. M. hyorhinis and MHS ELISA performance, evaluated using serum samples collected over a 56-day observation period from pigs inoculated with MHR, MHS, M. hyopneumoniae, M. flocculare, or Friis medium, varied by assay, targeted antibody isotype, and cutoffs. The progressions of MHR and MHS clinical diseases were evaluated in relation to the kinetics of the isotype-specific antibody response in serum and bacterial shedding in oral fluids during the observation period. In pigs inoculated with MHR, bacterial DNA was detected in one or more of the 5 pens at all sampling points throughout the study, IgA was first detected at DPI 7, one week before the first clinical signs, with both IgA and IgG detected in all samples collected after DPI 14. The peak of MHS shedding (DPI 8) coincided with the onset of the clinical signs, with both IgA and IgG detected in all serum samples collected ≥ DPI 14. This study demonstrated, under experimental conditions, that both ELISAs were suitable for early detection of specific antibodies against MHR or MHS. The diagnostic performance of the MHR and MHS ELISAs varied depending on the selected cutoff and the antibody isotype evaluated. The high diagnostic and analytical specificity of the ELISAs was particularly remarkable. This study also provides insights into the infection dynamics of MHR-associated disease and MHS-associated arthritis not previously described.

Highlights

Mycoplasma hyorhinis (MHR) [1] and Mycoplasma hyosynoviae (MHS) [2] are bacteria lacking cell walls within the class Mollicutes
Two animals within the same pen were euthanized at DPI 24 due to anorexia and inability to ambulate as a result of polyarthritis and polyserositis
In the last several years, there has been an increase in MHR-associated disease and MHS-associated arthritis in growing pigs resulting in significant production losses due to reduced growth rate, increased mortality or culling, and antibiotic costs [14,15]

Summary

Introduction

Mycoplasma hyorhinis (MHR) [1] and Mycoplasma hyosynoviae (MHS) [2] are bacteria lacking cell walls within the class Mollicutes Members of this class include several mycoplasmas that can be detected in various host species which differ significantly in their structure, habitat and growth requirements and are recognized as the smallest prokaryotic cells (0.2 and 0.8μm) capable of self-replication [3,4]. M. hyosynoviae has an affinity for joints, causing synovitis and arthritis, most commonly in pigs greater than 10-weeks-of-age [5,6]. M. hyorhinis-associated disease has recently emerged as an important contributor to mortality in nursery pigs and has become a major concern within the U.S swine industry [8,9]. Unlike MHS, MHR causes polyserositis (inflammation of several serous membranes) as well as arthritis [11,12,13]

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