Context:

In a bid to make babies immune to infection by the human immunodeficiency virus (HIV), a researcher from the Southern University of Science and Technology in Shenzhen, China, used a clinically untested gene editing tool (CRISPR-Cas9) to modify a particular gene.

The tool has also been used on another woman to make a gene-edited embryo; the pregnant woman is expected to deliver in August.

The announcement of the birth of gene-edited twin girls late last year set off an international furore.

Another usage Gene-editing technique: Scientists edit chicken genes to make them resistant to bird flu:

Scientists in Britain have used gene-editing techniques to stop bird flu spreading in chicken cells grown in a lab – a key step towards making genetically-altered chickens that could halt a human flu pandemic.

Bird flu viruses currently spread swiftly in wild birds and poultry and can at times jump into humans.

Global health and infectious disease specialists cite as one of their greatest concerns the threat of a human flu pandemic caused by a bird flu strain that makes such a jump and mutates into a deadly and airborne form that can pass easily between people.

This is an important advance that suggests we may be able to use gene-editing techniques to produce chickens that are resistant to bird flu.

Blocking the Virus and make resistant to bird flu:

In the further work, the team hopes to use the gene editing technology, known as CRISPR, to remove a section of the birds’ DNA responsible for producing a protein called ANP32, on which all flu viruses depend to infect a host.

Lab tests of cells engineered to lack the gene showed they resist the flu virus – blocking its entry and halting its replication and spread.

The death toll in the last flu pandemic in 2009/10 – caused by the H1N1 strain and considered to be relatively mild – was around half a million people worldwide. The historic 1918 Spanish flu killed around 50 million people.

To disable a gene called CCR5: Was it wrong to use the gene tool?

Dr.He used the CRISPR–Cas9 gene editing technique in the twin girls to disable a gene called CCR5, which encodes a protein that allows HIV to enter and infect cells.

Though no guidelines have been drawn up so far, there is a general consensus in the scientific and ethics communities that the CRISPR–Cas9 gene-editing technique should not be used clinically in embryos.

There is also consensus that gene editing can be potentially used only to prevent serious genetic disorders that have no alternative treatment. While HIV cannot be cured, medicines can keep the virus under check.

Apparently, information on the consent form suggests that the parents who had participated in the experiment were never told about the problems of disabling the gene.

Can disabling the CCR5 gene prevent HIV?

It is generally believed that babies without a functional CCR5 gene will become resistant to HIV infection, certain other strains of HIV use another protein (CXCR4) to infect cells.

Hence, even people who are born with two copies of the non-functional CCR5 gene are not completely protected or resistant against HIV infection.

There is also the possibility that the gene editing tool could have caused unintended mutations in other parts of the genome, which may lead to unpredictable health consequences.

Most importantly, medicines and delivery through caesarean section and avoiding breast feeding can prevent vertical viral transmission from mother to foetus.

While women with HIV have greater chances of passing the virus to the foetus.

Way Forward: What steps has China taken to prevent misuse?

Importantly, human clinical trials have not been carried out anywhere in the world to test whether disabling the gene completely prevents HIV infection and what the side-effects of doing so would be.

In the absence of any clinical trial data as well as consensus to use this tool to prevent HIV infection, performing it on babies as a form of medical intervention is unethical.

According to The Scientist, Dr. He’s experiment violates the 2003 guidelines that prohibits the use of gene-manipulated embryos for reproductive purposes.

On February 26, China posted the draft regulation requiring researchers to obtain prior approval from the government before undertaking clinical trials.

On January 21 this year, Dr. He was fired from the university where he worked after a probe by the Guangdong health commission found that he had violated the national regulations against using gene-editing for reproductive purposes.

Those found violating the rules will be punished and this includes a lifetime ban on research. China is now all set to introduce gene-editing regulation.