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Veterinary Bacterial Zoonoses

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Front. Vet. Sci. | doi: 10.3389/fvets.2018.00028

Limitations of using IL-17A and IP-10 to detect bovine tuberculosis

 Xin Ting1,  Xintao Gao1, Hongjun Yang2, Pingjun Li1, Qianqian Liang1, haohua Hou1, Xiukun Sui1, Xiaoyu Guo1, Weifeng Yuan1, Hongfei Zhu1,  Jiabo Ding3* and Hong Jia1*
  • 1Institute of Animal Sciences (CAAS), China
  • 2Shandong Academy of Agricultural Sciences, China
  • 3China Institute of Veterinary Drug Control, China

Bovine tuberculosis (bTB) is primarily caused by infection with Mycobacterium bovis, which belongs to the Mycobacterium tuberculosis complex (MTC). The airborne route is considered the most common for transmission of M. bovis, and more than 15% of cattle with bTB shed the mycobacterium, which can be detect by nested PCR to amplify mycobacterial mpb70 from a nasal swab from a cow. To screen for cytokines fostering early and accurate detection of bTB, peripheral blood mononuclear cells (PBMCs) were isolated from naturally M. bovis-infected, experimentally M. bovis 68002-infected, and uninfected cattle, then these cells were stimulated by PPD-B, CFP-10-ESAT-6 (CE), or phosphate-buffered saline (PBS) for 6 h. The levels of IFN-γ, IP-10, IL-6, IL-12, IL-17A, and TNF-α mRNA were measured using real-time PCR. To explore the cytokines associated with different periods of M. bovis infection, cattle were divided into three groups: PCR-positive (PCR-P), PCR-negative (PCR-N), and uninfected using the tuberculin skin test (TST), CFP-10/ESAT-6/TB10.4 protein cocktail-based skin test, interferon gamma (IFN-γ) release assay (IGRA), CFP-10/ESAT-6 (CE)-based IGRA, and nested PCR. The expression of IP-10, IL-17A, and IFN-γ proteins induced by PPD-B, CE, or PBS was detected by ELISA. The results showed that levels of PPD-B-stimulated IL-17A and IP-10 (mRNA and protein), and CE-induced IP-10 (mRNA and protein) were significantly higher in cattle naturally or experimentally infected with M. bovis than in those that were uninfected. The levels of PPD-B- or CE-induced IL-17A and IP-10 (protein) could be used to differentiate M. bovis-infected calves from uninfected ones for 6 to 30 weeks post-infection, whereas PPD-B- and CE-induced IP-10 and IL-17A mRNA expression could be used to differentiate M. bovis-infected calves from uninfected ones between 6 and 58 weeks post-infection. However, CE-induced IL-17A (protein) was not a reliable indicator of M. bovis infection in cattle that were confirmed positive for infection by nested PCR. Furthermore, the levels of PPD-B- or CE-induced IP-10 and IL-17A protein were lower than IFN-γ in M. bovis-infected cattle. Therefore, IL-17A and IP-10 protein are not suitable biomarkers for bTB. Antigen-induced IP-10 mRNA should be analyzed further for their potential to be used in the diagnosis of bTB.

Keywords: bovine tuberculosis, IP-10, IL-17A, IFN-γ, Nested PCR

Received: 21 Sep 2017; Accepted: 09 Feb 2018.

Edited by:

Massimo Amadori, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna Bruno Ubertini (IZSLER), Italy

Reviewed by:

Kaori Sakamoto, University of Georgia, United States
Christian Menge, Friedrich Loeffler Institut Jena, Germany  

Copyright: © 2018 Ting, Gao, Yang, Li, Liang, Hou, Sui, Guo, Yuan, Zhu, Ding and Jia. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Prof. Jiabo Ding, China Institute of Veterinary Drug Control, Beijing, China, dingjiabo@126.com
Dr. Hong Jia, Institute of Animal Sciences (CAAS), Beijing, China, jiahong80@126.com