Alex Rose-Innes
Outbreaks of avian influenza (bird flu) have cost billions of dollars around the world, with more than seven million slaughtered in South Africa in the first half of this year to stop the spread of the disease. This is but a drop in the bucket as the global estimate is much higher with chickens killed (since October 2021) in the United States of America as a result of the disease, amounting to more than 140 million. This killer flu has now been found as far as Antarctica.
Relying on Scientists to stop another human epidemic
The biggest threat this virus holds is the potential to start another human pandemic. This fear is well-founded as the three flu pandemics of the 20th century originated from birds, including the 1918 flu pandemic that claimed tens of millions of lives – originated from birds.
As One Health Day was celebrated, the health threats between people, animals and the environment, was highlighted.
Research associate at the University of Bristol, Alewo Idoko-Akoh, in an international science publication, explained how advances in the gene-editing of chickens could eliminate avian flu.
“In a recent gene editing study, my colleagues and I showed the potential of gene editing to protect chickens from avian influenza. This disease is caused by an ever-evolving virus able to avoid around numerous biosecurity measures such as good hygiene, restricting bird movements, surveillance through appropriate testing and selective elimination of infected birds. A gene editing breakthrough would stem the huge economic losses currently suffered as a result of bird flu outbreaks. It would also be a significant step in controlling a disease that can cause serious sickness and death in humans,” he said.
Vaccinations can only do so much to stop avian influenza
Vaccination is the primary method for preventing avian influenza outbreaks in chickens. However, the effectiveness of vaccines is limited because the bird flu virus rapidly evolves, making existing vaccines less effective over time. Also, there are multiple strains of the avian influenza virus and a vaccine is effective against a specific strain only, much the same as COVID-19.
It is necessary to match a vaccine with the prevailing strain causing an outbreak. Using vaccines may also involve substantial costs and practical hurdles of distribution, especially on the African continent.
Gene editing to improve animal welfare
In contrast to vaccinations, gene editing targets a protein or proteins within chickens that are vital for all strains of avian influenza, effectively stopping the virus in its tracks. Gene editing refers to the process of making a precise change in a specific gene in an animal to introduce traits such as resistance to a particular disease, increased productivity and characteristics that enhance animal welfare.
A beneficial genetic change introduced into an animal using gene editing may already occur naturally in another animal. For example, gene editing was used to make dairy cattle hornless by introducing into them a genetic change found in naturally hornless cattle. This is important as many dairy cattle have horns, resulting in the painful practice of dehorning calves to reduce the risk of injury to the animal and the farmer.
It is important not to confuse gene editing with genetic modification, which entails transferring a gene from one species to another. This distinction is necessary for regulatory purposes, especially as the older genetic modification technology has faced stringent regulations in many countries, hampering its development.
“To produce the gene-edited chickens in our study, we used the powerful molecular scissors known as CRISPR/Cas9 to make a single gene edit. We targeted the ANP32A protein in chickens. Compared to normal chickens hatched simultaneously, these gene-edited chickens reached maturity without any discernible adverse consequences on their health and wellbeing. To test their resistance, we exposed the gene-edited chickens to a low dose of the bird flu virus. Remarkably, 9 out of 10 of these birds displayed complete resistance, and no transmission occurred to other chickens,” Idoko-Akoh explained.
Taking a more ambitious step, the scientists involved in the study, inoculated the gene-edited chickens with a high, unnatural dose of the virus – 1,000 times the low dose. This time, 5 out of the 10 inoculated gene-edited chickens became infected. They also found that the bird flu virus was capable of adapting to use the edited ANP32A protein, as well as two related proteins – ANP32B and ANP32E. “But we demonstrated through experiments in cells that simultaneously editing all three proteins could completely suppress the virus,” he told Science Direct.
What the future holds
Ongoing research aims to identify the specific combination of gene edits needed to create the next generation of gene-edited chickens, providing complete and permanent protection against avian influenza. Gene editing should be regarded as an essential tool for preventing and controlling deadly animal diseases. Supportive government regulations will be required to promote the development of gene editing aimed at enhancing animal health and welfare.
The potential for disease resistant animals to protect global food security and public health is a compelling reason to pursue this innovative path in biotechnology.
