A former Iowa State University scientist who altered blood samples to make it appear he had achieved a breakthrough toward a potential vaccine against HIV was sentenced Wednesday to more than 4 1/2 years in prison for making false statements in research reports.

Dong-Pyou Han, 58, also must pay $7.2 million to a federal government agency that funded the research. He entered a plea agreement in February admitting guilt to two counts of making false statements.

Government prosecutors said Han's misconduct dates to 2008 when he worked at Case Western Reserve University in Cleveland under professor Michael Cho, who was leading a team testing an experimental HIV vaccine on rabbits. Cho's team began receiving NIH funding, and he soon reported the vaccine was causing rabbits to develop antibodies to HIV, which was considered a major breakthrough. Han said he initially accidentally mixed human blood with rabbit blood making the potential vaccine appear to increase an immune defense against HIV, the virus that can cause AIDS. Han continued to spike the results to avoid disappointing Cho, his mentor, after the scientific community became excited that the team could be on the verge of a vaccine.

Iowa State recruited Cho in 2009, and his team - including Han - continue the research with NIH funding. A group of researchers at Harvard University found in January 2013 the promising results had been achieved with rabbit blood spiked with human antibodies.

Han's attorney Joseph Herrold, a federal public defender, asked for probation instead of prison.

"Here, there is little reason to believe that Dr. Han has not already been deterred from any future criminal conduct. His conduct is aberrational in an otherwise admirable life," Herrold wrote in a sentencing report filed Monday. "He regrets the hurt he has caused to his friends and colleagues, the damage he has caused to government funded scientific research, and the pain he has caused any members of the public who had high hopes based on his falsehood."

Herrold said Han has lost the ability to work in his field of choice and is likely to be deported by immigration officials "and possibly never permitted to return," separating him from his wife and two adult children who are U.S. citizens. Han, who was born in Seoul, South Korea, is a lawful permanent U.S. resident.

Government prosecutors sought prison time to serve as a deterrent to Han and others who might consider research fraud.

"It is important that we stand up not just for punishing the fraud committed against the United States government, but for the research that should be legitimately taking place on this devastating disease," U.S. Attorney Nicholas A. Klinefeldt said in a statement.

Judge James Gritzner sentenced Han to 57 months in prison and three years of supervision upon release. Han must repay the National Institutes of Health $7.2 million.

Cho's team continues to work on the vaccine at ISU and has subsequently obtained funding.