A Mount Pleasant-based biotechnology firm that was courted by cities around the country is staying within town limits as it embarks on a major business expansion.

GenPhar Inc., which develops vaccines against dangerous infectious diseases, including the deadly Ebola virus, said it will invest $33 million to relocate its headquarters to Innovation Park at the Market at Oakland Plantation from Low Country Boulevard.

The 20-worker company will expand its payroll to more than 140 high-skilled employees earning $40 an hour on average, said John Dong, president and chief scientific officer. The new 50,000-square-foot facility will include a high-tech manufacturing area featuring a 10,000-square-foot "clean" room, along with corporate offices and laboratory space. It is scheduled for completion in May 2008.

Dong said economic development officials from more than a dozen locations had tried to recruit it, including San Francisco, Seattle, Houston, Pittsburgh and North Carolina's Research Triangle Park. But he said he stuck with the Charleston region, partly because of the quality of life and partly because of the presence of the Medical University of South Carolina.

"There is an untapped talent pool in this region," Dong said. "I believe MUSC has teaching and research programs in the same class as many Ivy League schools." He described the research and technology being developed at the Medical University of South Carolina as "the best-kept secret in the nation."

At the same time, that technology for the most part "has not been tapped into," Dong said. For the town, the GenPhar deal helps ease the sting of losing software maker Benefitfocus.com, which left Mount Pleasant for Daniel Island. Myles Stempin, coordinator of the town's economic development office, said he hopes the new investment will shift some attention to Mount Pleasant and serve as a magnet for other biotech employers.

GenPhar was founded in 1999 with about 20 scientists and other workers. It has been working in numerous partnerships with other companies and the federal government. GenPhar said it is one of just two organizations in the world developing a vaccine for the Ebola virus. Dong estimated the firm's vaccine is less than a year away from being ready to start the approval process with the U.S. Food and Drug Administration. He stressed that only the vaccine work is handled locally. The dangerous virus samples are stored at a secure military laboratory in Maryland.

GenPhar, which receives some of its funding from Department of Defense projects, also is hoping to capture a slice of the $5.6 billion allocated to the federal Project BioShield program, which was signed into law in 2004 as part of an effort to develop remedies against bioweapons. "That's our next target," Dong said after announcing the expansion Tuesday at the Charleston Regional Development Alliance's headquarters.

GenPhar also is working on vaccines that could be sold in the commercial market.