A group of scientists led by Eske Willerslev from the University of Copenhagen discovered traces of hepatitis B in the DNA of a person who lived about 4.5 thousand years ago. This is the oldest evidence of the existence of a virus found so far. The research results are reported by Science Alert.
Experts have isolated DNA from the teeth and temporal bones of the skeletons of 137 people from nomadic peoples who lived 2000-7000 years ago. To do this, biologists used the shotgun method, when long chains of DNA are split into overlapping fragments, which are then inserted into vectors - circular molecules that are copied in bacterial cells. This creates a genomic library. Randomly selected fragments are sequenced, that is, the sequence of nucleotides is determined, after which they are combined into larger chains.
This method allows biologists to compare newly deciphered DNA sequences with the already known ones, which are contained in databases. In addition, the genomes of 167 people were analyzed, sequenced in another study. In 25 people, one of whom lived 4.5 thousand years ago, fragments of nucleic acids belonging to the genome of the hepatitis B virus, which is able to fully or partially integrate into the host's DNA, were identified.
Prior to this discovery, the earliest traces of the hepatitis B virus were 450 years old. The results of the study show that the infection has been widespread in Eurasia for several thousand years.
According to the US Centers for Disease Control and Prevention, 786,000 people worldwide die from hepatitis B each year.