TY - JOUR

T1 - Structure-function relationships of the antigenicity of mycolic acids in tuberculosis patients.

AU - Beukes, Mervyn

AU - Lemmer, Yolandy

AU - Deysel, Madrey

AU - Al-Dulayymi, Juma'a

AU - Baird, M.S.

AU - Koza, Gani

AU - Maza Iglesias, Maximiliano

AU - Schubert-Rowles, Richard

AU - Theunissen, Cornelia

AU - Grooten, Johan

AU - Toschi, Gani

AU - Roberts, Vanessa V.

AU - Pilcher, Lynne

AU - Van Wyngaardt, Sandra

AU - Mathebula, Nsovo

AU - Balogun, Mohammed

AU - Stoltz, A.C.

AU - Verschoor, Jan

N1 - Open Access funded by Wellcome Trust

PY - 2010/11/1

Y1 - 2010/11/1

N2 - Cell wall mycolic acids (MA) from Mycobacterium tuberculosis (M.tb) are CD1b presented antigens that can be used to detect antibodies as surrogate markers of active TB, even in HIV coinfected patients. The use of the complex mixtures of natural MA is complicated by an apparent antibody cross-reactivity withcholesterol. Here firstly we report three recombinant monoclonal scFv antibody fragments in the chicken germ-line antibody repertoire, which demonstrate the possibilities for cross-reactivity: the first recognized both cholesterol and mycolic acids, the second mycolic acids but not cholesterol, and the thirdcholesterol but not mycolic acids. Secondly, MA structure is experimentally interrogated to try to understand the cross-reactivity. Unique synthetic mycolic acids representative of the three main functional classes show varying antigenicity against human TB patient sera, depending on the functional groupspresent and on their stereochemistry. Oxygenated (methoxy- and keto-) mycolic acid was found to be more antigenic than alpha-mycolic acids. Synthetic methoxy-mycolic acids were the most antigenic, one containing a trans-cyclopropane apparently being somewhat more antigenic than the natural mixture.Trans-cyclopropane-containing keto- and hydroxy-mycolic acids were also found to be the most antigenic among each of these classes. However, none of the individual synthetic mycolic acids significantly and reproducibly distinguished the pooled serum of TB positive patients from that of TB negative patients better than the natural mixture of MA. This argues against the potential to improve the specificity of serodiagnosis of TB with a defined single synthetic mycolic acid antigen from this set, although sensitivity may be facilitated by using a synthetic methoxy-mycolic acid.

AB - Cell wall mycolic acids (MA) from Mycobacterium tuberculosis (M.tb) are CD1b presented antigens that can be used to detect antibodies as surrogate markers of active TB, even in HIV coinfected patients. The use of the complex mixtures of natural MA is complicated by an apparent antibody cross-reactivity withcholesterol. Here firstly we report three recombinant monoclonal scFv antibody fragments in the chicken germ-line antibody repertoire, which demonstrate the possibilities for cross-reactivity: the first recognized both cholesterol and mycolic acids, the second mycolic acids but not cholesterol, and the thirdcholesterol but not mycolic acids. Secondly, MA structure is experimentally interrogated to try to understand the cross-reactivity. Unique synthetic mycolic acids representative of the three main functional classes show varying antigenicity against human TB patient sera, depending on the functional groupspresent and on their stereochemistry. Oxygenated (methoxy- and keto-) mycolic acid was found to be more antigenic than alpha-mycolic acids. Synthetic methoxy-mycolic acids were the most antigenic, one containing a trans-cyclopropane apparently being somewhat more antigenic than the natural mixture.Trans-cyclopropane-containing keto- and hydroxy-mycolic acids were also found to be the most antigenic among each of these classes. However, none of the individual synthetic mycolic acids significantly and reproducibly distinguished the pooled serum of TB positive patients from that of TB negative patients better than the natural mixture of MA. This argues against the potential to improve the specificity of serodiagnosis of TB with a defined single synthetic mycolic acid antigen from this set, although sensitivity may be facilitated by using a synthetic methoxy-mycolic acid.

KW - Mycolid Acids

KW - Cholesterol

KW - Monoclonal antibodies

KW - Tubercolosis

KW - Diagnostics

KW - Antigenicity

U2 - 10.1016/j.chemphyslip.2010.09.006

DO - 10.1016/j.chemphyslip.2010.09.006

M3 - Article

VL - 163

SP - 800

EP - 808

JO - Chemistry and Physics of Lipids

JF - Chemistry and Physics of Lipids

SN - 0009-3084

IS - 8

ER -