Using DNA samples from a 500-year old mummified remains of a child, researchers were able to crack the genetic code of an ancient strain of the hepatitis B virus (HBV).
The finding, wherein scientists were able to “sequence the complete genome” of the virus, could help medical experts understand the intricacies of HBV, which is a “pervasive, complex, and deadly pathogen that today kills nearly one million people every year.” Although its evolutionary history and origin remain a mystery, the data they shared establishes the fact that HBV has plagued humans for hundreds of years.
The 16th-century remains, which was buried in the Basilica of Saint Domenico Maggiore in Italy, was at first analyzed to be an infection of the Variola virus (commonly known as smallpox) — with experts even thinking that this was the “oldest evidence for the presence of smallpox in Medieval remains” that had a critical time stamp as proof of its origins. However, earlier studies did not include DNA testing as part of the procedure.
Now, with advanced sequencing techniques, researchers now posited that the mummified child was indeed infected by HBV. Children infected with HBV may develop the Gianotti-Crosti syndrome, which includes a facial rash similar to those found in the mummy, which could have been misidentified as smallpox. This just goes to show how complex the process of identifying infectious diseases in the past was.
Hendrik Poinar, an evolutionary geneticist with the McMaster Ancient DNA Centre, said: “These data emphasize the importance of molecular approaches to help identify the presence of key pathogens in the past, enabling us to better constrain the time they may have infected humans.”
The researchers extracted small tissue samples of skin and bone from the mummified child, which then yielded “tiny fragments of DNA.” The group then pieced together these fragments of genetic information to form a “more complete picture.”
While their findings have identified the connection between both “the ancient and strains of HBV,” they are both missing “temporal structure.” This means that “there is no measurable rate of evolution throughout the 450-year period which separates the mummy sample from modern samples.”
Since viruses evolve very quickly, evolution may only take a couple of days. In this case, scientists believe this particular ancient strain of HBV hasn’t changed much despite its age and that its evolution is complex. (Related: Hepatitis B Vaccines in Infants: Helpful or Harmful?)
According to some estimates, 350 million people are currently diagnosed with chronic HBV infections, and one-third of the global population has been infected with the virus at least once in their lives. With these numbers, researchers believe that it is important to prioritize studies on ancient viruses.
Hendrick Poinar, a principal investigator with the Michael G. DeGroote Institute for Infectious Disease Research, concluded that further study on the behavior of earlier pandemics and outbreaks could help us understand how modern pathogens could work and spread. Using this information, we could effectively control diseases such as HBV.
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