CalTech team creates one-time contraceptive vaccine for feral animals

Bruce Hay

Scientists have already made strides with immunotherapies, or treatments that spur the immune system to fight diseases. But now researchers at the California Institute of Technology are taking the idea one step further, developing a one-time contraceptive vaccine that uses hormone antibodies to spay or neuter animals.

The CalTech team's injection inserts packaged DNA into mouse muscle cells, prompting them to produce antibodies that neutralize male and female reproductive hormones. Researchers found that two months after receiving the shot with anti-gonadotropin-releasing hormone (GnRH), male mice could not sire offspring and did not experience any side effects. Scientists also saw that female mice injected with another antibody became infertile. The researchers published their findings in a recent issue of Current Biology.

The findings could have broad implications for animal health, as scientists look for cheaper ways to neuter and spay wild animals population control, senior study author Bruce Hay said in a statement. "Spaying and neutering wild animals is not a trivial process--it takes money and time to anesthetize them, do the surgery, and let them recover," Hay said. "This is a much more benign way of managing populations."

Meanwhile, researchers are looking for ways to optimize the jab. An obstacle to the current method is the lag time between when an animal gets an injection and when they become fully infertile. Gene delivery could speed up the process, Hay said, and Caltech scientists are investigating that possibility. Hay and his team are also running a pilot study of the shot on female cats with Cincinnati Zoo's Center for Conservation and Research of Endangered Wildlife to see how well it can manage local populations.

The CalTech team's vaccine could also hold promise for permanent human contraception, Hay said, although more work still needs to be done to test its efficacy. The advent of gene therapy has made it easier to deliver antibodies to patients, but scientists are still refining the technology.

CalTech researchers are not the only ones creating contraceptive vaccines for animals. Earlier this year, Harvard University engineer David Mooney scored a $700,000 grant from the Los Angeles-based Michelson Found Animals Foundation to develop an injectable contraceptive for pets. Mooney said he plans to use funds to adapt his cancer-fighting technique for the shot, designing a one-time injection that would spur the immune system to attack reproduction hormones.

- here's the Cell Biology study abstract
- read the statement

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