Gene-edited chicken resistant to avian leukosis virus

Can Gene Editing Stop Bird Flu? How Scientists Are Making Chickens Resistant

Mira Elwood in Tech & Innovation September 2025 • 5 min read.

"Revolutionary CRISPR technology offers new hope in the fight against avian leukosis virus and other poultry diseases, promising safer and more resilient food supplies."

Avian leukosis virus subgroup J (ALV-J) has caused significant economic losses in the poultry industry worldwide since its emergence in the late 1980s. This virus has been a persistent threat because all chicken lines studied to date are susceptible to ALV infection. This widespread vulnerability has fueled an urgent need to develop resistant chicken populations to safeguard the poultry industry and ensure a stable food supply.

Traditional methods of disease control in poultry farms have often fallen short, leading to continuous cycles of outbreaks and economic strain. Current strategies include strict biosecurity measures, vaccination programs, and in some cases, culling infected birds. However, these methods are not always effective in preventing the spread of ALV-J, particularly given the virus's ability to transmit both horizontally and vertically.

Now, gene editing offers a promising new approach. Recent advancements in CRISPR-Cas9 technology have opened the door to precise modifications of the chicken genome, offering the potential to create chickens inherently resistant to ALV-J. This innovative strategy focuses on altering the host's genes to prevent viral entry and replication, rather than simply managing the symptoms or spread of the disease.

How Does CRISPR Gene Editing Work in Chickens?

Gene-edited chicken resistant to avian leukosis virus

The key to making chickens resistant to ALV-J lies in understanding how the virus infects cells. ALV-J enters chicken cells by attaching to a specific receptor on the cell surface called chicken Na+/H+ exchanger type 1 (chNHE1). This protein acts as a doorway for the virus, allowing it to penetrate and replicate within the chicken's cells.

Scientists have discovered that modifying the chNHE1 receptor can prevent the virus from attaching and entering the cell, thus conferring resistance. The CRISPR-Cas9 system provides a precise way to make these modifications. This system works like a pair of molecular scissors that can cut DNA at specific locations. By targeting the chNHE1 gene, researchers can edit its sequence, disrupting the virus's ability to bind.

Identifying the Target: Researchers pinpoint the exact location on the chNHE1 gene that needs modification to disrupt viral binding.
Designing the Guide RNA: A guide RNA is created to match the target DNA sequence on the chNHE1 gene. This guide RNA leads the Cas9 enzyme to the precise location.
Making the Cut: The Cas9 enzyme, guided by the RNA, cuts the DNA at the targeted site on the chNHE1 gene.
Disrupting the Gene: Once the DNA is cut, the cell's natural repair mechanisms kick in. These mechanisms can either disrupt the gene entirely, creating small insertions or deletions (indels), or incorporate a new DNA sequence provided by the scientists.

One critical area of focus is a specific amino acid on the chNHE1 receptor called tryptophan 38 (Trp38). Studies have shown that modifying or deleting this amino acid can significantly reduce the virus's ability to infect cells. By using CRISPR-Cas9 to target Trp38, scientists can create chickens that are highly resistant to ALV-J.

What's Next for Gene-Edited Chickens?

The success of gene editing in creating ALV-J resistant chickens offers a promising path forward for disease control in the poultry industry. While these initial results are encouraging, further research is needed to fully understand the long-term effects of these genetic modifications. One key area of focus is ensuring that the changes do not inadvertently affect other important traits in the chickens, such as growth rate, egg production, or immune function. Also, the public acceptance and regulatory approval of genetically modified poultry will be critical for widespread implementation.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.dci.2017.09.006, Alternate LINK

Title: Precise Gene Editing Of Chicken Na+/H+ Exchange Type 1 (Chnhe1) Confers Resistance To Avian Leukosis Virus Subgroup J (Alv-J)

Subject: Developmental Biology

Journal: Developmental & Comparative Immunology

Publisher: Elsevier BV

Authors: Hong Jo Lee, Kyung Youn Lee, Kyung Min Jung, Kyung Je Park, Ko On Lee, Jeong-Yong Suh, Yongxiu Yao, Venugopal Nair, Jae Yong Han

Published: 2017-12-01

Everything You Need To Know

How does gene editing make chickens resistant to avian leukosis virus (ALV-J)?

Scientists are using CRISPR-Cas9 technology to modify the chicken genome, specifically targeting the chicken Na+/H+ exchanger type 1 (chNHE1) receptor. By editing the chNHE1 gene, particularly a specific amino acid called tryptophan 38 (Trp38), they can prevent the avian leukosis virus subgroup J (ALV-J) from attaching to and entering the chicken cells, thus making the chickens resistant to the virus. This method alters the host's genes to prevent viral entry and replication.

How does avian leukosis virus subgroup J (ALV-J) infect chicken cells?

The avian leukosis virus subgroup J (ALV-J) enters chicken cells by attaching to the chicken Na+/H+ exchanger type 1 (chNHE1) receptor on the cell surface. This receptor acts as a doorway for the virus. Once attached, the virus penetrates the cell and begins to replicate. By modifying the chNHE1 receptor using CRISPR-Cas9, scientists disrupt the virus's ability to bind and enter the cell, thus preventing infection.

Can you explain how the CRISPR-Cas9 system works to modify the chicken genome?

The CRISPR-Cas9 system works by using a guide RNA to direct the Cas9 enzyme to a specific location on the chicken's DNA, such as the chNHE1 gene. The Cas9 enzyme then cuts the DNA at this targeted site. The cell's natural repair mechanisms kick in to repair the cut, which can either disrupt the gene entirely, creating insertions or deletions (indels), or incorporate a new DNA sequence. By targeting the tryptophan 38 (Trp38) amino acid on the chNHE1 receptor, scientists can significantly reduce the virus's ability to infect cells.

What are the potential long-term implications and considerations for using gene-edited chickens in the poultry industry?

While gene editing shows promise in creating chickens resistant to avian leukosis virus subgroup J (ALV-J), it's crucial to assess potential long-term effects on other important traits like growth rate, egg production, and immune function. Further research is needed to ensure that these genetic modifications do not inadvertently affect these traits. Additionally, public acceptance and regulatory approval of genetically modified poultry will be critical for widespread implementation.

Why is gene editing being explored as a solution to avian leukosis virus subgroup J (ALV-J), and what makes it different from traditional methods of disease control?

Avian leukosis virus subgroup J (ALV-J) has been a persistent threat because all chicken lines studied to date are susceptible to ALV infection, causing significant economic losses in the poultry industry worldwide since its emergence in the late 1980s. Traditional methods like biosecurity, vaccinations, and culling have not been fully effective due to the virus's ability to spread horizontally and vertically. Gene editing offers a new strategy by creating chickens inherently resistant to ALV-J, reducing reliance on these less effective methods.