The Diagnosis of Mycobacterium avium Infections Using Serodiagnosis With Novel Lipid Antigens

Abstract

Mycobacterium avium subspecies Paratuberculosis (MAP) is an endemic pathogen in ruminants, present in a high proportion of herds worldwide. Its presence within cattle herds creates an economic burden on both farmers and the wider economy; due to lost milk production and premature culling.
Currently there is a lack of sensitive and rapid detection techniques, as culture can take months to give results and traditional PCR cannot distinguish viable from non-viable cells. Tests utilising defined synthetic mycolic acids and their sugar esters have already shown promise at diagnosing tuberculosis. This will form the basis of work described here, translating those procedures to the detection of MAP using both ELISA and a flow through device.
MAP has also been shown to survive pasteurisation, thus making it into the food chain, and has been proposed as an aetiological agent for the development of Crohn’s disease.
• First, a study of strongly positive experimentally infected cattle samples against negative serum from a herd with no history of MAP resulted in a single antigen sensitivity/specificity of 100/100.
• Second, a study of 40 negative and 40 positive, naturally infected cattle samples from Canada resulted in a sensitivity/specificity of 85/75. Combined with the first study and utilising all 5 common antigens for diagnosis resulted in a sensitivity/specificity of 84/93
• Initial testing and translation of flow through procedures from M. tb to MAP with a pooled cattle sample resulted in defined red spots, with the control remaining clear.
• MAP specific antigens tested against human Crohn’s samples as compared with healthy samples resulted in a single antigen sensitivity/specificity of 91/100
This work has identified promising antigens for further large-scale testing against both MAP in cattle and Crohn’s disease. Additionally, the first test of a flow through device shows promise in developing a rapid point of care device for the detection of MAP.