Research could help disarm deadly retroviruses such as HIV or SARS

Taken to its ultimate outcome, the research that biology professor Dr. Steve Howard is working on could help disarm deadly retroviruses such as HIV or SARS.

Howard, associate professor of biology at Middle Tennessee State University, would be the first to advise against making that kind of quantum-leap claim. It's much too early. But assuming that the research that led to the polio vaccine first crawled, then walked, then charted a new course for civilization itself, Howard's discovery is more than significant.

Co-authored by Drs. J.F. Fontanari and A. Colato of the Universidade de Sao Paulo in Brazil, Howard's study was published recently in the Physical Review Letters, the top international journal in physics.

"I became aware of a paper these two theoretical physicists published, and it turns out they were interested in some of the same questions that I had been interested in," Howard said.

Trained as a population geneticist and evolutionary biologist, Howard had always been intrigued by the process in which organisms become adapted to their environments. He was particularly interested in understanding how the process of evolution affects the relationship between disease-causing organisms and other organisms that are infected by these organisms. Research over the past several years points to a genetic base for these infections.

"There are certain sequences of DNA in these viruses and other disease-causing organisms that enable them to infect humans or other species that have certain sequences of DNA. In other words, there is a lock-and-key mechanism in determining the genetic basis to infections," he explained.

"What we're interested in is understanding the potential for random mutations to accumulate in the genetic material of viruses to the point where there are so many mistakes in the DNA or RNA that they can no longer reproduce or maintain themselves."

Howard said that determining the expected rates at which these mutations could accumulate all distills down to a math problem. It was with this realization that the three researchers linked up and discovered they could make more headway by combining their efforts.

"We used a mathematical approach—known as 'branching process theory'—to generate a theoretical prediction concerning the rate at which random mutations could accumulate in the genetic material of viruses like HIV," Howard continued. "The result we got was extraordinary. What we found was that under certain conditions, the rates that these mistakes can accumulate is actually accelerated by the process of natural selection. This is surprising, as natural selection typically leads to a reduction in the number of mutations. … The implication is that we could accelerate the rate at which these virus populations go extinct."

If viruses like HIV accumulate a sufficient number of these genetic mistakes, then they will cease to function. Howard compared the genetic corruption to making changes on a blueprint for a building.

"How many times would those changes improve the building? he posed. "Not very often."

Howard said he hopes that other biologists will get involved and do research on this acceleration process. Careful not to overstate the ramifications, he emphasized again how important this step is in the entire process of speeding up viral degeneration.

"What we show is that during that phase where things are transferred—at the point when they start to invade your body—that's where this process of acceleration potentially can take place. The question is, how can we take advantage of that?"

Emerging new diseases have scientists concerned, Howard noted. Many diseases are jumping boundaries. SARS somehow made the leap beyond China, its apparent point of origin.

"Viruses replicate quickly, and new strains can evolve like wildfire. … Viruses can also adapt quickly to changes in the environment."

Howard said he and his colleagues in Brazil will continue to work together.

"We have just obtained a solution for the problem in situations where population size fluctuates," he added. "I am now writing up the results for publication."