Executive Summary

Gain-of-function (GOF) and loss-of-function (LOF) research are two valuable methodologies that allow scientists to study pathogens. These interconnected research approaches alter pathogens’ genomes to add or subtract functionality, allowing scientists to examine and better understand how pathogens function and develop new vaccines and therapies.

Despite its widely recognized value for science, gain-of-function research has attracted attention and concern from U.S. policymakers due to what some see as inherent risks in this methodology, particularly following the outbreak and debated origins of the COVID-19 pandemic. The risk that gain-of-function research could inadvertently contribute to pandemics or widespread illness has sparked discussion about new regulations. LOF research results in weakened pathogens—and thus does not impart the same risks as GOF research—and is rarely mentioned in policy debates in the same way as GOF research.

In this report, we map the gain- and loss-of-function global research landscape using a quantitative approach that combines machine learning with subject-matter expert review. We identify about 7,000 PubMed research papers related to our criteria for GOF and LOF research, published between 2000 and mid-2022. Our research shows that GOF and LOF research are intertwined; they are conducted using the same experimental procedures and thus would both be impacted by any future regulations. As such, throughout this report, the two types of research are often discussed in tandem. Our aim is to help policymakers understand the research landscape in order to more effectively mitigate risks without impacting beneficial GOF and LOF research.

Our key findings include:

1. Gain- and loss-of-function research is ongoing, global, and collaborative with U.S.-affiliated researchers contributing to approximately half of identified publications between 2000 and mid-2022.
2. Gain- and loss-of-function research frequently co-occur in the same study. That said, LOF research appears in more publications than GOF research.
3. Gain- and loss-of-function research is conducted over a range of different experimental methodologies, pathogens, and applications.  
   • Methodologies: GOF and LOF research does not require cutting-edge gene-editing technologies; 21 percent of all publications we identified for this report use serial passaging instead of other more technically sophisticated techniques such as CRISPR. The use of serial passage is more frequent in GOF publications than LOF publications.
   • Pathogens: GOF and LOF research involves pathogens that span the four biosafety levels (BSLs), with nearly all research being conducted on pathogens that are categorized as BSL-2, BSL-2+, or BSL-3.
   • Applications: a range of research topics involve GOF and LOF research. For example, approximately 24 percent of the identified publications were related to vaccine development and the most-studied pathogens are those that cause high global health burdens.

Based on our analysis, we assess that GOF and LOF research will be difficult to regulate because:

1. Gain- and loss-of-function research are widely used in public health applications. Regulations will need to target the types of research that cause the most risk without impeding disease research or therapy development.
2. Gain- and loss-of-function research are intertwined. Regulations that restrict GOF research will also restrict less risky LOF research, potentially delaying public health developments without achieving the desired safety enhancements.
3. Researchers cannot always predict whether an experiment will cause a pathogen to become more or less virulent. Experiments that were not anticipated to be GOF research may not be prevented by proactive regulatory requirements.
4. Gain-of-function research can be conducted without access to gene editing technologies. Regulating gene editing technologies, including CRISPR or DNA synthesis, would not affect the approximately 21 percent of experiments that were conducted using serial passaging.
5. Risk varies among GOF studies, and should not be uniformly regulated.  The risk level of GOF and LOF research changes based on experimental factors including the pathogen’s biosafety level, methodology, and the animal model(s) used. Regulations will need to target the types of research that cause the most risk rather than impose a one-size-fits-all regulatory policy that does not account for these vital differences.