Molecular Detection of Past Pathogens.

Detection and characterisation of DNA is the most widely used approach for the study of past pathogens. This approach can be applied to various specimens, including environmental, vector and animal reservoir specimens as well as human corpses. Experimental data indicated that host-associated microbial DNA can survive for 20,000 years, and bacterial DNA preserved in permafrost specimens has been dated up to 1 million years. Current protocols targeted one pathogen at a time and universal 16S rDNA-based detection of bacteria have yielded ambiguous results. There is no universal detection of ancient virus so far. Major human pathogens, e.g. Mycobacterium tuberculosis, Mycobacterium leprae, Yersinia pestis, Rickettsia prowazekii, Bartonella spp. and Spanish influenza virus have been detected in suitable human specimens. Ancient M. tuberculosis and Y. pestis organisms have been genotyped, whereas the entire RNA genome of Spanish influenza virus was reconstituted for extensive studies. Metagenomic approaches based on high throughput pyrosequencing may help further resolve forthcoming issues. Interpretation of experimental data has to be based upon strict rules due to potential contamination of specimens. [ABSTRACT FROM AUTHOR]