Clinical Application And Antigenicity Of ESAT-6/CFP-10 Fusion Protein For Diagnosis Of Tuberculosis

Objective:To analyze the specificity of ESAT-6/CFP-10 fusion protein as an antigen of tuberculosis,and To evaluate the clinical application of ESAT-6/CFP-10 enzyme-linked immunospot(ELISPOT) assay for diagnosis of tuberculosis.Methods:Using ELISPOT to compare antigenicity of ESAT-6/CFP-10 fusion protein and PPD,and to analyze the specificity and superiority of ESAT-6/CFP-10 fusion protein as an antigen of tuberculosis;and using the ESAT-6/CFP-10-ELISPOT for detection of T cells with secretion of IFN-γspecific for M.tuberculosis antigens in blood samples from 65 patients only with tuberculosis,16 patients with co-infection HIV and TB,32 with other respiratory diseases,and 30 healthy persons.And the results compare with traditional diagnostic method of tuberculosis.Results:As a specific antigen,ESAT-6/CFP-10 fusion protein has the same antigenic action with PPD in tuberculosis patient,and using PPD could lead to false positive with BCG-vaccinated healthy persons,but ESAT-6/CFP-10 fusion protein was negative.The positive rates of ESAT-6/CFP-10-ELISPOT for the 81 patients with tuberculosis were 98.8%.The positive rates of PPD skin test were 56.8%.The positive rates ESAT-6/CFP-10-ELISPOT of were significantly higher than those of TST(PPD skin test).The positive rates of ESAT-6/CFP-10-ELISPOT for 30 patients with smear positive tuberculosis,35 patients with smear negative tuberculosis(include12 extrapulmonary tuberculosis),16 patients with co-infection HIV and TB were 100%, 97.1%,100%in these three groups,respectively.The sensitivity much higher than sputum smear exam.This method has a sensitivity of 98.8%,specificity of 98.8%.Conclusion:1.ESAT-6/CFP-10 fusion protein shows even higher sensitivity and specificity than PPD and single antigen.And it dose not suffer from interference of BCG-vaccinated.So ESAT-6/CFP-10 fusion protein is a valuable specific antigen for diagnosis of tuberculosis.2.ESAT-6/CFP-10-ELISPOT is a rapid,sensitive,and specific method.And this method has better diagnostic value than other traditional methods.3.ESAT-6/CFP-10-ELISPOT has highly sensitivity and specificity to diagnose all kinds of tuberculosis,especially,SNPT,extrapulmonary tuberculosis,co-infection HIV and TB and to distinguish other respiratory diseases.And this method has a higher positive rate than conventional TST(PPD skin test) with LTBI.It will be a useful tool to take the place of TST to early and rapidly diagnose tuberculosis patients.4.Assessment standard of ESAT-6/CFP-10-ELISPOT to divide whether or not infection is some number of point.As yet,the meaning of specific numbers in point is unknown.