Contraceptive vaccine reduces fertility in animals to address wildlife overpopulation

WEST LAFAYETTE, Ind. — A Purdue University contraceptive vaccine seeks to address animal overpopulation by markedly reducing fertility in feral horses, deer, swine and other animals.

Dr. Harm HogenEsch, distinguished professor of immunopathology in Purdue University’s College of Veterinary Medicine, and Dr. Raluca Ostafe, director of Purdue University’s Molecular Evolution Protein Engineering and Production Facility, both members of the Purdue Institute for Inflammation, Immunology and Infectious Disease, have designed the vaccine based on the IZUMO1 mammalian sperm protein. It induces a robust and long-lasting immune response and infertility in female mammals.

The research has been published in the Feb. 6 issue of the peer-reviewed journal Vaccine.

“Attempts to make an effective vaccine against sperm proteins have failed or only had modest success,” HogenEsch said. “Our vaccine overcomes the limitations of existing contraceptive vaccines.”

HogenEsch disclosed the contraceptive vaccine to the Purdue Innovates Office of Technology Commercialization, which has applied for a patent to protect the intellectual property. Industry partners interested in developing or commercializing it should contact Joe Kasper at jrkasper@prf.org about track code 70624.

Humane World for Animals, formerly the Humane Society of the United States, and the Elinor Patterson Baker Trust provided financial support for HogenEsch’s research.

HogenEsch and his colleagues have also now completed the first year of a three-year project funded by the Bureau of Land Management to test the vaccine’s effects on horses. If successful, this could have application to wild horse management.

Drawbacks of traditional contraceptive vaccines

There are currently two types of contraceptive vaccines, both based on self-proteins, which require a breakdown of immune tolerance.

HogenEsch said these vaccines have several drawbacks:

• They reduce fertility, but the effect is not long-lasting.
• They are associated with injection site reactions ranging from swelling to abscesses.
• One vaccine targets hormones that could cause behavioral changes.
• One vaccine is prepared from sources that are at risk to supply chain interruptions.

HogenEsch’s contraceptive vaccine addresses these limitations.

“It is based on a male sperm protein that the female’s immune system recognizes as foreign,” he said. “It works exclusively by inhibiting the fusion of a sperm cell and the oocyte. The vaccine consists of a well-defined peptide produced in mammalian cells and an effective and safe adjuvant.”

Validation and next development steps

The successful production and purification of the Purdue vaccine were validated via Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) and western blot analysis of the proteins. Its ability to reduce fertility was experimentally observed by injecting different formulations into experimental groups; vaccination reduced fertility 59% to 67% overall.

HogenEsch plans to conduct further research into the contraceptive vaccine.

“We will develop it into a single-dose, controlled-release formulation. This is critical to the use of the vaccine in wildlife where giving a second dose to an animal is often very difficult if not impossible. A vaccine that induces long-lasting infertility with a single injection will greatly facilitate the utility of the vaccine,” he said. “We are also working to further optimize the design of the vaccine to allow delivery via darts and oral delivery.”

About Purdue Innovates Office of Technology Commercialization

The Purdue Innovates Office of Technology Commercialization operates one of the most comprehensive technology transfer programs among leading research universities in the U.S. Services provided by this office support the economic development initiatives of Purdue University and benefit the university’s academic activities through commercializing, licensing and protecting Purdue intellectual property. In fiscal year 2025, the office reported 161 deals executed with 269 technologies licensed, 479 invention disclosures received and 267 U.S. and international patents received. The office is managed by the Purdue Research Foundation, a private, nonprofit foundation created to advance the mission of Purdue University. Contact otcip@prf.org for more information. 

About Purdue University

Purdue University is a public research university leading with excellence at scale. Ranked among top 10 public universities in the United States, Purdue discovers, disseminates and deploys knowledge with a quality and at a scale second to none. More than 106,000 students study at Purdue across multiple campuses, locations and modalities, including more than 57,000 at our main campus in West Lafayette and Indianapolis. Committed to affordability and accessibility, Purdue’s main campus has frozen tuition 14 years in a row. See how Purdue never stops in the persistent pursuit of the next giant leap — including its integrated, comprehensive Indianapolis urban expansion; the Mitch Daniels School of Business; Purdue Computes; and the One Health initiative — at https://www.purdue.edu/president/strategic-initiatives.