Study of immune proteins in individuals from a leprosy and non-leprosy associated cemetery

This study investigates the efficacy of proteomic analysis of human remains to identify active Mycobacterium leprae infections in the past. Mycobacterial diseases, like leprosy, have plagued human populations for millennia. Thanks to effective treatment options, leprosy is not as widespread and deadly as in the past, yet remains endemic in certain regions. We present a sequential-enzyme, optimised extraction protocol, using trypsin and ProAlanase, to increase the recovery of non-collagenous proteins through a study of five individuals from an 11th to 18th century leprosarium, as well as four from a contemporaneous non-leprosy associated cemetery in Barcelona. We demonstrate that skeletal samples from the leprosarium individuals contain numerous immune proteins associated with modern leprosy, while those from the non-leprosy associated cemetery do not. Through this study, we advance a palaeoimmunology methodology, gain insights into the health of archaeological individuals and offer a means to triage ideal samples for aDNA analysis.