"Infertility Virus" to Sterilize Stray Cats: New Gene Therapy Approach Could Work on Humans, Too

Female Cats Do Not Even Want to Mate After Getting Infected with this AMH-expressing Adenovirus

A fascinating scientific discovery could finally help us solve the problem of stray cats reproducing out of control.

The custom adenovirus AAV9-fcMISv2 is designed to prevent stray cats from reproducing. The virus causes few symptoms and feels “just like a cold.” It makes female cats infertile and unwilling to mate.

In the new study, Pépin, Swanson, and colleagues inserted the cat version of the AMH gene into a harmless virus widely used in gene therapy to ferry replacement genes into cells.

Scientists designed “gene therapy” that transfects novel genes into female cats. (thus “gene therapy”.) They discovered that making feline bodies produce a so-called “antimüllerian hormone” would stop reproductive processes.

That changed when an unusual pair of scientists came together. David Pépin, a reproductive biologist at Massachusetts General Hospital, spent his early career researching antimüllerian hormone (AMH), which is produced by follicles in the ovary that give rise to eggs. When, in one experiment, he amped up the expression of the hormone in female mice, their ovaries stopped forming follicles, sterilizing the animals.

The adenovirus expressing this hormone (abbreviated AMH) works so well that female felines lose interest in mating. Despite putting males and females in one cage for extended periods, females displayed a reduced desire to mate, and no kittens were born even when mating took place, as the Nature article explains:

However, when estrus is defined behaviorally by the female permitting mounting and coitus, an effect of treatment can clearly be observed. All three control females mated repeatedly with both males, whereas four of the six treated females rebuffed every mating attempt by the breeder males during both mating trials (Table 1 and Supplementary Tables 1 and 2).

In contrast, no AAV9-fcMISv2-treated females gave birth during either trial and no gestational sacs or fetuses were observed at weekly ultrasound exams. Because no kittens were born from treated females, we did not assess maternal-fetal transmission of AMH.

I guess having fewer stray cats is a good thing. And yet, think about the possibilities: someone could design another virus that infects humans, which would render us infertile.

A nicely designed human infertility virus could appear to be “just a cold” that no one would worry about or notice. Humans also are affected by a similar anti-mullerian hormone, as this study explains:

Conversely, AMH is inhibitory but the decline of its expression, amplified by E2, allows full expression of aromatase, characteristic of the large antral follicles. We propose a theoretical scheme made up of two triangles that follow each other chronologically. In PCOS, pre-antral follicle growth is excessive (triangle 1) because of intrinsic androgen excess that renders GCs hypersensitive to FSH, with consequently excessive AMH expression.

People familiar with PCOS know that women affected by it have difficulties getting pregnant. So, while I am not a biologist, I can easily see that there are many possibilities for virus developers to create a “just a cold” virus that would shut down human reproduction while seeming to be totally mild.

Since Omicron infected most people on Earth within a few months since its debut, a sufficiently infectious (but “mild”) AMH-expressing virus could spread before we understand anything.

No virologist would ever do that to us, right?