Genotypic analysis of Mycobacterium tuberculosis from medieval human remains

Three medieval bone samples with osteological evidence of tuberculosis infe ction were analysed for the presence of DNA sequences from Mycobacterium tu berculosis using a series of PCRs. In each case amplification of IS6110 and part of the beta-subunit of RNA polymerase identified infection with a bac terium belonging to the M. tuberculosis complex. Amplification of the mtp40 genome fragment and the presence of a guanine residue at position 285 in t he oxyR pseudogene, demonstrated the infecting strain to be similar to pres ent day M. tuberculosis isolates rather than to Mycobacterium bovis. Spolig otyping, based on amplification of the direct repeat (DR) region of the myc obacterial genome, provided further evidence of similarity to M. tuberculos is and indicated a close relationship between isolates associated with two separate medieval burials. The study demonstrates the feasibility of amplif ying multiple nn. tuberculosis loci in ancient human remains and suggests i mportant applications in the study of the palaeoepidemiology and virulence of tuberculosis in past populations.