Evaluation of IFIT3 and ORM1 as Biomarkers for Discriminating Active Tuberculosis from Latent Infection

Objective Current commercially available immunological tests cannot be used for discriminating active tuberculosis(TB)from latent TB infection.To evaluate the value of biomarker candidates in the diagnosis of active TB,this study aimed to identify differentially expressed genes in peripheral blood mononuclear cells(PBMCs)between patients with active TB and individuals with latent TB infection by transcriptome sequencing.Methods The differentially expressed genes in unstimulated PBMCs and in Mycobacterium tuberculosis(Mtb)antigen-stimulated PBMCs from patients with active TB and individuals with latent TB infection were identified by transcriptome sequencing.Selected candidate genes were evaluated in cohorts consisting of 110 patients with TB,30 individuals with latent TB infections,and 50 healthy controls by quantitative real-time RT-PCR.Receiver operating characteristic(ROC)curve analysis was performed to calculate the diagnostic value of the biomarker candidates.Results Among the differentially expressed genes in PBMCs without Mtb antigen stimulation,interferon-induced protein with tetratricopeptide repeats 3(IFIT3)had the highest area under curve(AUC)value(0.918,95%CI:0.852-0.984,P<0.0001)in discriminating patients with active TB from individuals with latent TB infection,with a sensitivity of 91.86%and a specificity of 84.00%.In Mtb antigen-stimulated PBMCs,orosomucoid 1(ORM1)had a high AUC value(0.833,95%CI:0.752-0.915,P<0.0001),with a sensitivity of 81.94%and a specificity of 70.00%.Conclusion IFIT3 and ORM1 might be potential biomarkers for discriminating active TB from latent TB infection.