Hepatitis B virus has a long history

The hepatitis B virus was discovered in the second half of the 60s of the last century. But people were sick with hepatitis, of course, before that. If you try to trace the genealogy of the virus, which goes back millennia, you can find a lot of interesting things.

It is necessary, of course, to reconstruct the history of the virus not from medical records: although epidemics of jaundice have been known since ancient Babylon, there are several hepatitis viruses in nature. If we want to study, for example, the hepatitis B virus, we need its DNA from ancient human remains, and it is desirable that these remains are from all over the world. A large group of researchers from the Institute for Evolutionary Anthropology Max Planck Society, The University of Adelaide, Moscow State University, the Peter the Great Museum of Anthropology and Ethnography of the Russian Academy of Sciences (Kunstkamera), the Institute of Ethnology and Anthropology of the Russian Academy of Sciences and a number of scientific centers in Russia, Germany, the United States and other countries compared 137 viral genomes found on the remains of residents of Eurasia and America is between 10,500 and 400 years old. These genomes were compared with the genomes of the modern hepatitis B virus.

We are talking about the genomes of the modern virus in the plural because it exists in several varieties. In an article in Science all current variants of the virus are said to have evolved from a single strain that spread among humans at the end of the Pleistocene, between 20,000 and 12,000 years ago. Moreover, it spread both among the ancient Eurasians and among the inhabitants of South America. We have already written about the antiquity of the hepatitis B virus, then it was about the fact that it has been living with people since at least the Bronze Age – however, as we can see, it turned out to be much older.

If we talk about Europe, then at least 10 thousand years ago the hepatitis B virus was already quite common here and was transmitted with might and main in the tribes of the then hunter-gatherers. In this sense, it differs from many other pathogens that came to people only with the Neolithic revolution, that is, with the development of agriculture. True, with the development of agriculture, the old strains of the hepatitis B virus gave way to new ones, which developed and spread simultaneously with changes in human history. However, the “agricultural” strains of the hepatitis B virus have not changed for millennia, despite the active migration across Eurasia of steppe cattle breeders of Yamnaya and other crops.

But in the second half of the second millennium BC, the diversity of Eurasian strains drops sharply – which is probably somehow connected with the next socio-cultural perturbations. It is unclear exactly why the genetic diversity of hepatitis B virus strains dropped so dramatically at the time. But, one way or another, of all the ancient strains widespread in Eurasia, in a more or less unchanged form, only one has survived to the present day – this living fossil, quite rare now, is called the genotype G.

The rest of the strains look newer, but this does not mean that they came to people from an independent source – as mentioned above, they trace their ancestry from the same virus that spread around the world at the end of the Pleistocene, it just accumulated more changes over time … Perhaps, in the future, they will also expect some changes, and it remains to be hoped that we will be ready for them, armed with the knowledge about the evolution of the virus.

Source: Автономная некоммерческая организация "Редакция журнала «Наука и жизнь»" by www.nkj.ru.

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