CRISPR Gene Editing Makes Chickens Resistant to Bird Flu, Offers Breakthrough in Animal Immunity Against Infection

Since 2022, health authorities have confirmed the wide geographic spread of highly pathogenic avian influenza (HPAI) viruses in wild birds and poultry. Although only a small number of sporadic human cases have been identified, it has wiped out millions of chicken flocks and wild bird populations.

What is HPAI?

Avian flu, or bird flu, is an infection caused by influenza Type A viruses that spread among birds. There are different strains of avian influenza, but most do not infect humans.

Bird flu viruses are classified into low pathogenic avian influenza (LPAI) A viruses or high pathogenic avian influenza (HPAI) A viruses. HPAI can cause severe disease and high mortality in infected poultry.

Only A(H5) and A(H7) viruses are classified as HPAI among the many strains of bird flu viruses. They can cause diseases that affect multiple internal organs, with up to 90% to 100% mortality in chickens. This viral infection in poultry can also affect wild birds, which results in further geographic spread since those birds migrate.

Improved Bird Immunity With Genetic Modifications

One conventional way to protect poultry from catching avian flu is by keeping them away from wild birds that can transmit the disease. However, this technique is not ideal for the bird's wellbeing. Another possible approach is vaccination, but it is challenging in terms of cost and practicality. Aside from this, flu viruses can also mutate to evade vaccines.

In pioneering research, UK researchers used gene editing technology to create poultry partially resistant to avian flu infection. They used the gene-editing tool CRISPR to alter the ANP32 gene, which supports flu viruses inside the chicken's cells.

In this study, the research team produced ten chickens with the edited gene and exposed them to the H9N2 strain of bird flu, using a dose that resembles what they might experience in the real world. This strain was used instead of the more deadly H5N1 because it is the most likely to be encountered by chickens during an outbreak. The researchers discovered that only one of the ten chickens got infected, and the virus did not spread to other chickens.

The gene-edited birds were then exposed to an artificially high dose of the virus. Five out of 10 chickens got infected but were still provided with some level of protection. The virus found in the infected animals was much lower than the level typically detected among chickens that have become ill with bird flu.

The gene editing technology also helped in limiting the spread of the virus. When four ordinary chickens were placed in the same incubator with the genetically modified birds already exposed to high levels of the virus, only one became infected.

Over two years, the gene-edited birds were monitored by the researchers. The experts found that the gene changes had no adverse effects on their health or egg production.

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