Biotechnology firm Mediatech Inc. announced yesterday it will move its headquarters from Fairfax County to a 10-acre site in Prince William County, where it will build a $10 million, 100,000-square-foot manufacturing facility.

The facility, just outside Manassas, will be built with $1.2 million in grants, tax breaks and other incentives from Virginia and Prince William County, said James E. DeOlden, president and co-founder of the company.

The facility will be completed by late 2005 and create at least 100 new jobs, he said. Mediatech already has more than 100 employees at its current headquarters in Herndon. With more than 200 employees, Mediatech would become one of the largest biotech firms in Virginia.

The privately held, 20-year-old company makes solutions used to culture cells. Mediatech customers, including medical schools and biotechnology and pharmaceutical companies, use its products in research to develop more effective ways to treat human and animal diseases, such as diabetes.

"We've got to get out of here. We have no room," DeOlden said in a phone interview from his office in Herndon. "We have outgrown our space, which is a leased facility, and we need our own space. This is a wonderful opportunity."

The move to Prince William bolsters the county's reputation as a biotechnology center in Virginia, said Mark A. Herzog, executive director of the Virginia Biotechnology Association, a Richmond-based trade group.

"Mediatech's move to Prince William County is yet another in the long string of successes for the county," Herzog said. "The county has the right mixture of university research, private sector companies and a fantastic workforce."

Mediatech plans to move to the Innovation@Prince William Technology Business Park, which is also home to a George Mason University campus that specializes in biotechnology and biodefense; the American Type Culture Collection, a biological resource center; defense contractor Logis-Tech Inc.; and a planned insulin manufacturing plant run by Eli Lilly & Co.

DeOlden said Mediatech chose Prince William after a multi-state search. "We recognized the growing opportunities and resources Prince William County has to offer," he said in a statement. "Additionally, we recognized the advancing presence of biotechnology in the area and the potential opportunities to work closely with surrounding universities like George Mason as well as other top quality biotechnology companies."

DeOlden added in an interview that incentives offered by Virginia Gov. Mark R. Warner (D) and the Prince William Board of County Supervisors weighed heavily in the company's decision to stay in Virginia.

Warner approved a $400,000 grant from the Governor's Opportunity Fund that Prince William County plans to match.

The state also will offer tax incentives and subsidize some training for newly hired employees, DeOlden said. The incentives package was negotiated for Mediatech by the McLean office of real estate consulting firm Scheer Partners Inc.

DeOlden declined to disclose financial details about his company, except to say, "We're profitable."