Antigen-Specific IP-10 Release Is a Sensitive Biomarker of <i>Mycobacterium bovis</i> Infection in Cattle

<div><p>The most widely used ante-mortem diagnostic tests for tuberculosis in cattle are the tuberculin skin test and the interferon-gamma (IFN-γ) release assay, both of which measure cell-mediated immune responses to <i>Mycobacterium bovis</i> infection. However, limitations in the performance of these tests results in a failure to identify all infected animals. In attempting to increase the range of diagnostic tests for tuberculosis, measurement of the cytokine IP-10 in antigen-stimulated blood has previously been shown to improve the detection of <i>M</i>. <i>tuberculosis</i> and <i>M</i>. <i>bovis</i> infection, in humans and African buffaloes (<i>Syncerus caffer</i>), respectively. In the present study, 60 cattle were identified by the single intradermal comparative tuberculin test as tuberculosis reactors (n = 24) or non-reactors (n = 36) and the release of IFN-γ and IP-10 in antigen-stimulated whole blood from these animals was measured using bovine specific ELISAs. There was a strong correlation between IP-10 and IFN-γ production in these samples. Moreover, measurement of the differential release of IP-10 in response to stimulation with <i>M</i>. <i>bovis</i> purified protein derivative (PPD) and <i>M</i>. <i>avium</i> PPD distinguished between reactor and non-reactor cattle with a sensitivity of 100% (95% CI, 86%–100%) and a specificity of 97% (95% CI, 85%–100%). These results suggest that IP-10 might prove valuable as a diagnostic biomarker of <i>M</i>. <i>bovis</i> infection in cattle.</p></div

Correlation between IFN-γ and IP-10 release.

<p>Whole blood from non-reactor and reactor cattle was stimulated with either <i>M</i>. <i>bovis</i> PPD or <i>M</i>. <i>avium</i> PPD for 24 h at 37°C. The release of IFN-γ and IP-10 was highly correlated in these samples (r = 0.65; p < 0.0001).</p

Spontaneous IP-10 release in whole blood from reactor cattle.

<p>Whole blood from cattle (n = 12) was incubated with phosphate buffered saline for 24 and 48 h. IP-10 release showed a significant increase over time (* < 0.005).</p

IP-10 release in response to antigenic stimulation in reactor and non-reactor cattle.

<p>Whole blood from non-reactor (n = 16) and reactor (n = 12) cattle was incubated with <i>M</i>. <i>avium</i> PPD (PPDa) and <i>M</i>. <i>bovis</i> PPD (PPDb) for 24 h at 37°C. For reactor cattle, IP-10 release in response to PPDb was significantly greater than that in response to PPDa. Median values are shown (*, p < 0.0005).</p

IP-10 release in response to antigenic stimulation after (A) 24 h and (B) 48 h.

<p>Whole blood from bTB-positive cattle (n = 12) was incubated at 37°C with saline (PBS), <i>M</i>. <i>avium</i> PPD (PPDa), <i>M</i>. <i>bovis</i> PPD (PPDb) and ESAT-6/CFP-10 peptides (EC). IP-10 release in whole blood in response to PPDb and EC was significantly greater than that in blood co-incubated with PBS and significantly greater in response to PPDb than in response to PPDa. Median values and the differential IP-10 responses to PPDa and PPDb (ΔPPD) and PBS and EC (ΔEC) are shown (*, p < 0.01; **, p < 0.05).</p

Antigen-specific IP-10 release distinguishes between non-reactor and reactor cattle.

<p>Whole blood from non-reactor (n = 36) and reactor cattle (n = 24) was incubated with <i>M</i>. <i>bovis</i> PPD and <i>M</i>. <i>avium</i> PPD for 24 h at 37°C. The difference in IP-10 release in these samples (ΔPPD) was used to calculate, by ROC analysis, an optimal cut off value of 0.11 (dotted line). This distinguished between these groups with a sensitivity of 100% and a specificity of 97%.</p

Stable isotopic values of serum from captive badgers fed a diet of biscuits and peanuts.

<p>These plots use trophic enrichment factors (TEFs) derived from three captive animals fed on a biscuit-only diet. The TEF for each dietary source is represented by a mean and standard deviation for both axes (δ¹⁵N and δ¹³C), plotted using SIAR <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0053071#pone.0053071-Parnell1" target="_blank">[2]</a>. Additional data for earthworms are provided for comparison. a. May 2008 (16 badgers). b. June 2008 (10 badgers). c. July 2008 (10 badgers).</p

Mean isotopic changes for δ¹³C after lipid extraction (including P values and sample sizes from comparison T-tests) of dog biscuits, peanuts and badger blood serum and badger red blood cells (RBCs).

<p>Reported values are provided with only one decimal place, to reflect the accuracy and precision of the analytical machinery.</p

Mean isotopic values for δ¹⁵N and δ¹³C (lipid extracted) obtained from serum of three captive badgers fed on a controlled diet for one month, and the calculated trophic enrichment factors (TEF) for each animal.

<p>Isotopic values (with corrections for lipid extraction) are the mean of three samples for each badger and nine samples of biscuit. Reported values are provided with only one decimal place, to reflect the accuracy and precision of the analytical machinery. TEFs for serum were calculated by subtracting the mean stable isotopic values of the diet (biscuits) from that of serum.</p

Innate gene repression associated with infection in cattle: toward a gene signature of disease-0

<p><b>Copyright information:</b></p><p>Taken from "Innate gene repression associated with infection in cattle: toward a gene signature of disease"</p><p>http://www.biomedcentral.com/1471-2164/8/400</p><p>BMC Genomics 2007;8():400-400.</p><p>Published online 31 Oct 2007</p><p>PMCID:PMC2213678.</p><p></p>ected (A) and healthy control cattle (B). The lymphocyte and monocyte subpopulations are retained in peripheral blood mononuclear cells (PBMC)