Scientists Engineer Chimeric Bird Flu Virus with Weaponized Traits in Alarming Gain-of-Function Study

They made a super bird flu in a lab. On purpose. What could possibly go wrong?

May 06, 2025

This article originally appeared on Jon Fleetwood’s Substack and was republished with permission.

South Korea combines three bird flu viruses into a single engineered mutant, increasing viral stability, altering host targeting, and enhancing human cell entry.

South Korean researchers have created a Frankenstein lab-modified bird flu virus using hallmark gain-of-function (GOF) techniques, according to a new study published on May 5, 2025 in Virology Journal.

The paper reveals scientists constructed a chimeric virus with altered heat resistance, receptor binding, and cell entry capabilities by combining gene segments from three distinct influenza viruses and applying directed mutations to increase replication and stability.

Highly pathogenic avian influenza viruses require BSL-3 containment due to their potential for aerosol transmission and serious health risks.

The experiments come as the U.S. Department of Health and Human Services under the Trump administration recently announced a $500 million “next-generation” pandemic vaccine initiative focused on avian influenza bird flu.

The timing raises alarm over the use of high-risk virological techniques to create brand new, pandemic-level viruses under the guise of vaccine development, especially as the White House has confirmed that the COVID-19 pandemic was caused by a virus engineered with the same kind of experiments.

Heatproofing: Thermostability Engineered Through Directed Mutation

Researchers introduced specific mutations to enhance the thermal resilience of the virus—meaning it can survive longer under higher temperatures.

From the study:

“we identified a key mutation (R90K) that increases heat stability while preserving antigenicity.”
“combining the R90K and H110Y mutations (22W_KY) resulted in a synergistic increase in thermal stability and maintained HA activity without measurable reduction even after 4 h at 52 °C.”

These changes directly alter the physical durability of the virus, allowing it to persist in conditions that would otherwise degrade its infectivity.

Thermal stabilization is a functional enhancement, meeting the definition of gain-of-function.

Reprogramming: Engineered Gene Swaps Alter Replication Patterns

The authors further engineered viral replication traits by modifying the PB2 gene to boost replication in chicken eggs—a method that also impacted replication in mammals:

“the PB2 gene of PR8 was replaced with a prototypical avian PB2 gene to increase replication efficiency in embryonated chicken eggs and reduce replication efficiency in mammalian cells.”
“the PB2 gene of 01310, modified with I66M, I109V, and I133V mutations (referred to as 310-MVV), increased the replication efficiency of Y280-lineage H9N2 viruses compared with the wild-type PB2 gene of 01310.”

This deliberate alteration of replication in non-natural hosts like eggs is a textbook example of gain-of-function manipulation.

Construction: Reverse Genetics Used to Create New Virus

Using the pHW2000 plasmid-based system, scientists rebuilt influenza viruses from scratch:

“Recombinant viruses were generated using a pHW2000 plasmid-based reverse genetics system.”

Reverse genetics systems are commonly used in gain-of-function research to design viruses with novel traits not found in nature.

Retargeting: Receptor Tropism Modification Confirmed

The study confirms altered receptor interactions in the modified virus—a critical determinant of which species or tissues the virus can infect.

“the N193D mutation led to a reduction of the affinity of the 22W_MVV virus for 2,3-SA.”

Although the change reduced binding in this case, modifying receptor preference is still gain-of-function by definition, as it alters the host-virus interface.

Chimera: Constructed from Three Distinct Viruses

The new virus is a lab-built chimera formed by fusing gene segments from three separate flu strains:

“22 W HA and 22 W NA genes, along with six internal genomic segments (PB2, PB1, PA, NP, M, NS) from PR8 and a PB2 gene from 01310 containing the I66M, I109V, and I133V (MVV) mutations”

This means the final virus included:

Hemagglutinin (HA) and neuraminidase (NA) from clade 2.3.4.4b H5N1
Internal genes from A/Puerto Rico/8/1934 (PR8)
PB2 gene from A/Chicken/01310/Korea/2001 with MVV mutations

Such multi-strain reassortment is inherently risky and falls under the highest classifications of gain-of-function due to the unpredictability of the resulting virus.

Weaponization: Enhanced Human Cell Entry and Immune Response

The virus was also engineered for increased antigen uptake, boosting both immune response and intracellular entry:

“BEI-inactivated 22W_KY also elicited significantly stronger systemic IgG, mucosal IgA, and T-cell responses, especially in the lungs.”
“the highest level of intracellular entry was observed for BEI_22W_KY, confirming its superior effectiveness in penetrating cells.”

These enhancements suggest the modified virus is more effective at invading host cells—a major safety red flag when discussing lab-created pathogens.

This study, published without mention of gain-of-function oversight or biosecurity risk assessment, comes as EcoHealth Alliance remains under federal suspension for past gain-of-function violations.

Yet similar experiments are continuing abroad, echoing concerns raised after the COVID-19 pandemic about lab-created virus dangers.

Should this engineered virus escape containment accidentally or intentionally, it could ignite a global pandemic—ironically, the very scenario it was allegedly built to prevent.