After 25 years battling the mother of all viruses, have we finally got the measure of HIV? Three developments featured in this issue collectively give grounds for optimism that would have been scarcely believable a year ago in the wake of another failed vaccine and continuing problems supplying drugs to all who need them.

Perhaps the most compelling hope lies in the apparent "cure" of a man with HIV who had also developed leukemia. Doctors treated his leukemia with a bone marrow transplant that also vanquished the virus. Now the U.S. company Sangamo Biosciences is hoping to emulate the effect using gene therapy. If it works, and that is still a big if, it would open up the possibility of patients being cured with a single shot of gene therapy, instead of taking anti-retroviral drugs for life.

Anti-retroviral therapy (ART) is itself another reason for optimism. Researchers at the World Health Organization have calculated that HIV could be effectively eradicated in Africa and other had-hit places using existing drugs. The trick is to test everyone often, and give those who test positive ART as soon as possible. Because the drugs rapidly reduce circulating levels of the virus to almost zero, it would stop people passing it in through sex. By blocking the cycle of infection in this way, the virus could be virtually eradicated by 2050.

Bankrolling such a long-term program would cost serious money—initially around $3.5 billion a year in South Africa alone, rising to $8.5 billion in total. Huge as it sounds, however, it is peanuts compared with the estimated $1.9 trillion cost of the Iraq war, or the $700 billion spent in one go propping up the U.S. banking sector. It also looks small beer compared with the costs of carrying on as usual, which the WHO says can only lead to spiraling cases and costs.

The final bit of good news is that the cost of ART could keep on falling. Last Friday, Glaxo Smith Klie chairman Andrew Witty said that his company would offer all its medicines to the poorest countries for at least 25 per cent less than the typical price in rich countries. GSK has already been doing this for ART, but the hope is that the company may now offer it cheaper still and that other firms will follow their lead.

No one doubts the devastation caused by AIDS. In 2007, 2 million people dies and 2.7 million more contracted the virus. Those dismal numbers are not going to turn around soon—and they won't turn around at all without huge effort and investment. But at least there is renewed belief that, given the time and money, we can finally start ridding the world of this most fearsome of viruses.