The Bush administration made an ambitious new commitment to the global fight against AIDS, and last year, Congress authorized billions in new spending. But as the recession continues, lawmakers and philanthropists will retreat.

Thus it comes as a rare bit of good news that a Massachusetts businessman is giving $100 million of his own to the quest for an AIDS vaccine. Phillip T. Ragon, the founder of Cambridge-based software company InterSystems Corp., will allocate his gift in $10 million annual installments over 10 years to a new institute. Researchers from Massachusetts General Hospital, the Massachusetts Institute of Technology and Harvard University will join in an effort to find new approaches.

A vaccine has been the holy grail of AIDS research. But the HIV virus, which causes AIDS, has shown an uncanny ability to alter its makeup and elude destruction. The hope is that, for example, MIT engineers can lend new perspectives to the medical doctors, biologists and others who have already spent years tilling this hard soil. In the long run, the Ragon Institute’s objective is to find new ways of deploying the immune system against a variety of diseases, not just AIDS.

Mr. Ragon, who is establishing the institute with his wife, Susan, was inspired to act after a visit in 2007 to South Africa. There AIDS continues to devastate the population. Across the world, more than 25 million people have died of the disease since HIV was pinpointed as its cause.

Philanthropists everywhere are cutting back on or suspending charitable contributions. But what Mr. Ragon saw convinced him there was no time to waste. His inspiring example may encourage others leery of giving. May the Ragon Institute succeed.