BOSTON (AP) – A Norwegian company seeking to develop a male birth control pill has signed a licensing agreement with the University of Massachusetts Medical School covering research that could lead to a drug to block sperm’s ability to swim and fertilize an egg.

The method that led to the long-term deal announced Monday could expand the decades-long search for a male pill by targeting a protein found only in sperm cells.

Researchers at UMass in Worcester and elsewhere say that approach carries far less risk of side effects than manipulating a man’s hormones.

Terms of the deal with Oslo-based SpermaTech AS aimed at developing a drug based on the UMass-patented approach were not disclosed.

Risks from hormone therapy include harming the prostate gland and permanently reversing sperm production.

SpermaTech said it is searching for a molecular compound to block the so-called Cs protein, and is meeting with large drug companies to find a development partner.

Such a drug potentially could take the form of a pill, implant, patch or gel, and take as long as a decade to develop, De Paolo said.

“The challenge will be to come up with a compound that blocks the protein in the sperm without blocking other proteins in the body,” said Dr. John K. Amory, an assistant professor of medicine at the University of Washington with expertise in male contraceptive development.

In addition to potentially carrying few if any side effects, such a drug would be faster-acting than hormone therapy, which requires two to three months to affect male fertility because sperm cells require 72 days to fully mature, Amory said.

A 1998 research paper by Dr. George Witman, a UMass professor of cell biology, described the discovery in ram sperm of the Cs protein within sperm cells. After sperm cells form in the testes, the protein is inactivated as the cells travel through a coiled tube in a man’s body called the epididymis. The protein causes sperm cells’ tails to undulate, enabling them to potentially reach the female egg.

Witman and a UMass colleague, Dr. Jovenal San Agustin, eventually found that a protein nearly identical to the one in ram sperm also is found in human and mouse sperm.

A team from the University of North Carolina at Chapel Hill is conducting research similar to the UMass team that also involves targeting protein specific to sperm cells. That protein is a different form than the one targeted in the UMass research.