NEW YORK (AP) — Teva Pharmaceutical Industries Ltd. said Thursday it will invest $7.5 million in Cocrystal Discovery Inc. to start a partnership that develops treatments for viral diseases.

Cocrystal is a Bothell, Wash.-based biotech drugmaker that studies treatments for serious and chronic antiviral diseases such as hepatitis C and influenza. Its therapies are designed to be taken orally once per day. The agreement calls for Cocrystal to develop a hepatitis C treatment for Teva. Teva will have the option to make additional investments and the right to license the drug for development and sale.

The Israeli company can make further investments for the development of two other antiviral or antibacterial drugs, and if those investments are made, Teva would take a 23-percent stake in Cocrystal.

Teva is the world’s largest maker of generic drugs. It also makes brand-name drugs including Copaxone, which is the best-selling multiple sclerosis treatment by revenue, and it is also acquiring Cephalon Inc., which makes cancer drugs, the sleep disorder drug Provigil, and pain drugs like Fentora. Shares of Teva slipped 3 cents to $38.30 in afternoon trading.