The Howard Hughes Medical Institute has begun recruiting researchers for its $500 million biomedical research center in eastern Loudoun County and has announced its first two areas of research.

The institute is searching internationally for scientists who will serve as group leaders in biology, chemistry, computer science, engineering, mathematics and physics. The Janelia Farm campus in Ashburn is scheduled to open in 2006 and, when fully operational, will employ 20 to 30 group leaders and a permanent research staff of about 300.

"We are looking for scientists who are passionate in their pursuit of answers to particularly difficult problems in basic scientific and technical research," said Gerald M. Rubin, a geneticist who is director of the Janelia campus. "In return, our scientists will have unparalleled freedom and resources to explore those problems."

Initially, Janelia researchers will focus on two broad areas of scientific inquiry: how information is processed by the brain and how to improve imaging technologies that allow biologists, for example, to study the cells of live animals.

"Both of these programs are what I would call high-risk, high-reward areas of research," Rubin said. "Success in these areas is not guaranteed, and it will take a good deal of intellectual courage, but the impact could be enormous."

The Hughes institute plans to allow small, interdisciplinary research groups to explore cutting-edge scientific issues without having to worry about most of the administrative, grant writing and teaching duties that consume university-based academics. The Hughes researchers would also have more time to work on projects than the usual three to five years permitted under most federally funded grants, institute officials said.

"The institute's core belief is that scientists who demonstrate creativity and imagination can make lasting contributions to benefit humanity when they are given flexible, long-term support and the freedom to explore," said Thomas R. Cech, the institute's president.

Hughes officials said that in planning Janelia Farm, they studied the structure and scientific culture of other important biomedical laboratories, including the Medical Research Council Laboratory of Molecular Biology in England and the Bell Laboratories in the United States. They found that both institutions have small research groups whose key members work in the labs; both have one source of funds and forbid applying for outside grants; and both have good support services.

Rubin said the institute was looking for researchers at any stage in their careers and would consider applications from "exceptionally talented individuals working outside" the initial focus of scientific inquiry.

The deadline for applications is Dec. 15; a second round of recruiting will take place during 2005-06. Rubin said the first hires will arrive in Loudoun in the summer of 2006.

Loudoun officials hope Janelia will attract more biotechnology companies to the county, although Rubin said it was too early to know whether that would happen.

"Having a place like [Janelia] here is a . . . requirement to having a biotech industry" in the county, he said. "But it doesn't necessarily follow that by us being here, magically, a biotech industry will spring up."

The Board of Supervisors voted last year to give the institute nearly $6 million a year in tax breaks. Hughes backers said that granting the exemption would boost the county's economic fortunes and aid future taxpayers, as well as free up research money to battle disease. Opponents called it an irresponsible giveaway that rewards a multibillion-dollar nonprofit institution for eating up 281 acres of prime commercial real estate, land whose development could have produced tax revenue and eased budget pressures.

Rubin estimated that Janelia would spend $60 million on salaries of employees and contractors who live in the Loudoun area. He said that in addition to the 300 scientists, there will be 100 other professionals "who will probably be paid by someone else to come here and work for a while" plus contractors such as landscapers from the Loudoun area.

Staff writer Bill Brubaker contributed to this report.