Closed door

But there are people who are immune to this virus from birth. It is not a miracle. The path of the virus into human immune cells lies through a receptor on the surface of the cell which is called CCR5. It is like a “door” to the virus. Some people have a receptor (and this is a complex protein molecule) with a non-standard structure, a bit different. This is a genetically conditioned characteristic which is inherited.

This feature in the structure of the “door” is enough for the virus not to use it. If a person’s mother and father’s copies of the gene encode such a special variant of protein, then he/she will be immune to HIV.

The year before last, the Chinese scientist He Jiankui carried out an unprecedented experiment. He took human zygotes (it’s an organism that consists of a single cell) and used CRISPR/Cas9 technology to replace the “standard” gene of CCR5 with the “special” gene.

The CRISPR/Cas9 technology, also known as “genetic scissors”, is actually used to make changes to DNA in a precisely defined place. It has already been used to edit the human genome, but only on embryos whose development was stopped at a very early stage. It has been done with other genes and not for clinical purposes, but only “for science”.

This time the author of the experiment decided that children with an “improved” gene should be born. In 2018, the world learned about the birth of two girls with modified genes from an interview with a scientist. It should be said that this is quite unusual, because usually scientists report their results in specialized journals. But this time, the respectable journals where the researcher sent the article refused to print it, because the legality and ethics of the experiment were highly questionable.

He Jiankui said the experiment was a success. But since the scientific results were not officially published, one can only guess what they were really like. Later, copies of an article that had never been published leaked to the mass media.

Strange purpose

From the very beginning, specialists had many questions about this story. In particular, it is not clear to what extent the author of the experiment has achieved his goal and whether there have been other, unplanned mutations (it is very possible, and obviously can be very dangerous). What happens to children now is unknown, as there is no public information about them and their health.

This is not the only problem. Today, HIV-positive people can have absolutely healthy children, and parents of “genetically modified” girls, as far as we know, were HIV-negative. So, the matter was not that the Chinese scientist wanted to “cure” future children, he just wanted to protect them from hypothetical infection in the future. But to do it today by means of genome editing is something like shooting sparrows with a cannon. If one wanted so much to edit human genes, then it was possible to choose an important genetic disorder that causes the disease (although it would have also been illegal and only slightly more ethical). But He Jiankui chose an HIV-related gene – apparently given the well-known “brand” of the disease to the general public.

In general, the revolutionary experiment and its author did not find public support in the expert community. At the end of last year, the Chinese court fined him and sentenced him to three years of imprisonment.