A year ago, Yuntao Wu was on a roll. The George Mason University researcher had just published a study hailed by the scientific press as “groundbreaking” that reveals why HIV targets only a specific kind of T-cell and, separately, found that a compound in soybeans seemed to have promise for inhibiting infection.

These days, Wu — one of thousands of scientists who lost his grant in the wake of sequester cuts — says he spends much of his time hunched over a desk asking various people and organizations for money.

The deep across-the-board cuts in government spending that took effect March 1 have sent shock waves through the nation’s research labs, delaying research and forcing layoffs.

The budget for the National Institutes of Health, the world’s largest funder of biomedical research, shrank 5.5 percent. The National Science Foundation budget was trimmed by 2.1 percent. Research funding for the Centers for Disease Control and Prevention, NASA, the defense and energy departments, and other parts of the government that conduct research also were cut significantly.

The sequester has affected all parts of the government but the impact has been especially painful to those in biomedical research, where federal investment in inflation-adjusted dollars has decreased every year since 2003.

Since 1980, the debt ceiling has been raised 42 times.

Describing the scientific and medical community as “deeply demoralized,” NIH Director Francis Collins said in an interview that the budget cuts are delaying innovation and resulting in more American lives being lost.

“When you’re talking about developing cures, speed matters,” he said.

Among the critical projects that have lost resources, Collins said, is the effort to develop a universal flu vaccine that scientists hope might prevent pandemics.

The funding situation is unlikely to be resolved soon.

While Congress has an Oct. 1 deadline to pass a new spending bill for fiscal 2014, lawmakers are likely to pass a stopgap measure known as a continuing resolution to keep funding levels the same until the end of the year to give themselves more time to debate the issue.

Collins said that the NIH issued 640 fewer grants in the last fiscal year and that if the cuts continue at the same level next year, several hundred more projects will not be funded. He estimates that until recently, scientists applying for federal grants had a 1 in 3 chance of receiving funding. Now it’s more like 1 in 6.

“If you were going to start a new business and you had that kind of chance of being successful, I suspect you would find another way to find a living,” said Edward E. Partridge, director of the cancer center at the University of Alabama at Birmingham.

In a survey released this month, the American Society for Biochemistry and Molecular Biology and 15 other scientific organizations found that 54 percent of those who receive federal funding for scientific research said they have laid off or will lay off staff. And close to 1 in 5 scientists have considered moving overseas for better funding opportunities.

This summer, for instance, Vanderbilt University’s medical center cut hundreds of employees. The University of Chicago’s surgery department closed three labs. And the Roswell Park Cancer Institute in Buffalo has reduced the number of post-doctoral fellows it funds by 20.

Daniel Raben, professor of biological chemistry at the Johns Hopkins University School of Medicine, said he worries most about young researchers.

“Instead of trying to think about best science, they think about it as a business person. ‘Where’s the money? What’s the question that I can ask that can get money?’ And I find that to be very disheartening and even dangerous because we’re not going to make progress that way,” said Raben, who has had to lay off a technician and a graduate student.

Jeffrey Kuhn, 45, an adjunct professor at Virginia Tech who studies how cells move and cancer metastasizes, is among those who have had to rethink their career goals. After not getting a government grant, he is closing up his cell biology lab in Blacksburg this month.

Kuhn has said he is likely to move to Texas and accept private funding to work on a project involving a medical instrument that may have commercial applications. It’s not his passion, but he said he doesn’t have a choice. He needs the money.

“People are wasting so much time writing grant applications over and over again and not getting anywhere,” Kuhn said. “There was this research study on poverty and how much that influences your ability to think. There’s a 15-point IQ drop. That’s what’s happening in science these days.”

As for Wu, he said that he has gone from 14 paid employees to one post-doctoral candidate and that he’s still trying to cobble money from here and there to keep him going until the funding situation improves.

This summer, he raised more than $21,000 from friends and strangers through Crowdrise, a Web site, and took out a $20,000 loan from the university. He thinks he’ll be able to survive one more year. Then what?

“China,” said Wu, a professor at the National Center for Biodefense and Infectious Diseases at George Mason. “If there’s no money here either, you have to terminate your career or you have to move to another country.”