Diseases in Skeletons Identified in Just a Few Seconds
One such disease already benefiting from this technology is Tuberculosis (TB). By using a next-generation sequencing approach, including hybridisation capture technology, genes in a 19th century female skeleton could easily be identified. This fascinating study led by The University of Manchester, United Kingdom is part of wider research into identifying strains of TB in skeletons dating from 100 AD to the late 19th century.
The research is being led by Professor Terry Brown, in collaboration with Professor Charlotte Roberts from Durham University, United Kingdom to understand how TB has evolved over time. They hope their study will improve treatments and vaccines for the disease.
Currently, TB is a worldwide pandemic which kills around 1.7 million people a year. More than 80,000 cases occur in the European region - almost a fifth of the world's total. According to the World Health Organization (WHO) and Stop TB, 15 of the 27 countries with the highest burden of TB are in the European region.
How TB Affects Bones
Certain strains of TB can affect the sufferer's bones, especially in the spine as marks made by the disease remain on the bones long after the person's death. In order to screen for TB genes, Professor Roberts sourced 500 skeletons from across Europe which revealed evidence of TB dating from the Roman period to the 19th century.
Bone samples were screened for TB DNA and 100 skeletons were then chosen for further study.
Professor Roberts explains: 'So many skeletons were needed as it's very hard to tell if any DNA will have survived in the bones. You don't really know if there will be any present until you start screening and in the past that has been a lengthy process.'
Capturing of Sequences
Professor Brown and his team had the task of searching for TB DNA in the skeletons. Each small section of bone was ground up and placed in a solution, and then placed in a machine which captures every gene sequence in the DNA. Millions of sequences were captured and sent to a computer. Gene sequences for TB were then searched as the bacteria's DNA can remain in the bones after death.
Professor Brown elaborates on the process, 'Previously we could only scan the bone sample for specific genes. We wouldn't see everything that was there which meant we could easily miss other genetic information that could be relevant. Using the hybridization screening meant we could search for different strains of TB, not just one.'
This accuracy can also be a downside as the hybridization capture can mistakenly pick up DNA which isn't from the bone, but from the surrounding soil or environment where the skeleton was buried.
Double-check with PCR
In this study the results were checked using the more traditional method of polymerase chain reactions (PCRs) and were found to be accurate. The researchers concluded that using hybridization capture and next-generation gene sequencing is an accurate and effective way to obtain detailed genotypes of ancient varieties of TB. It could potentially be used to study other diseases. Their findings have been published in the journal Proceedings of the National Academy of Sciences.
Professor Roberts concludes: 'We're really pleased with the results of this study and that the technology works. It will save a lot of time in the future. We now hope to publish more of the huge amounts of data we have acquired from the sequencing.'
Scientists hope to compare their results with similar studies taking place in the United States to assess the types of TB strains which have already been identified. Of particular interest will be the strains brought to the country by migrants and the impact this had on the native strains of the disease.