Kai Brothers has been living with HIV for the past 30 years, having contracted the disease at 19 years-old in San Francisco. Had a blood bank not asked him to come in for a test, he wouldn't have even known he was sick, let alone HIV positive, because oddly enough, he never developed any symptoms. He recalls thinking: "I’m defying the odds here. There must be something my body is able to do that is keeping me healthy."

At his friend's suggestion in 1999, Brothers went to see leading AIDS researcher, Jay Levy, at the University of California, who had discovered the HIV virus in 1983. It turns out that Brothers's body was actually keeping the virus in check - specifically, his white blood cells were secreting an unidentified protein that somehow controls the most damanging aspects of the virus.

Levy suspects that being able to reproduce the effects of this protein could revolutionise HIV treatment. "We know what the protein does: It blocks the virus from replicating," Levy told Daniel A. Gross at Nautilus Magazine. "It maintains the virus in a silent state, in some people forever. Eventually the infected cells will die. So you could imagine that if you could keep this virus under control for 20, 30 years, you might have a spontaneous cure."

Levy has studied Brothers extensively, with Brothers crossing the US every six months to donate a total of 150 blood samples. "I think about all my friends every time I go. I just think, 'This is for you. And I wish you were still here,'" he told Gross.

But now - 26 years since being diagnosed - Brothers's health is becoming uncertain, with low white blood cells counts and a high amount of HIV present in his blood sample. He has to decide whether to take antiretroviral drugs, which will stop him producing this special protein, or continue on as he was, in the hopes that whatever was keeping him alive for so many years will continue doing so.

Kai Brothers Credit: Christa Brothers

The problem is, despite looking for this substance for 30 years, scientists haven't come up with a clear answer for what this protein might be. HIV functions by infiltrating the cell's DNA and then, when the cell replicates, the genes of the virus will be inside the new cell. But, strangely enough, if the cell is an immune cell - known as a dendritic cell - and contains a protein called SAMHD1, the cell will not replicate with the HIV virus.

Nathaniel Landau, a microbiologist from New York University in the US, told MEDICA.de that this occurs via a process known as nucleotide pool depletion: "SAMHD1 essentially starves the virus. The virus enters the cell and then nothing happens. It has nothing to build and replicate with, so no DNA is made," he sid.

While this is welcome knowledge, it only protects in one specific case - immune cells being infected with HIV. HIV can still replicate in other cells, and other viruses related to HIV, like HIV-2 and SIV, have developed a protein called viral protein X (VPX) that directly attacks SAMHD1.

So for Levy, with antiretroviral drugs being so advanced that they're now "pretty remarkable," many of his blood donors are jumping ship. Soon there might not be any "long-term survivors" to help him study this protein, he says. And, just as a virus evolves, so too does the human immune system. Without treatment, our bodies may evolve a way to combat the disease, but with the proliferation of HIV drugs, this won't be possible. One AIDS researcher, Douglas Richman of the University of California, called it an "arms-race".

Either way, it's leaving Brothers in a quandry, telling Gross at Nautilus Magazine: "I don’t feel like I’ve given everything I can. I want to be there when they find something and leverage it for other people. (But) it’s my priority to be healthy and alive more than anything else."

H/T Nautilus Magazine