UNL researcher: Yogurt bacteria could one day prevent HIV

Yogurt lines the shelves of a Lincoln grocery store. A researcher at the University of Nebraska-Lincoln is testing lactobacillus, or the "good bacteria" touted on yogurt labels, as a possible source of HIV prevention. (Photo by Hilary Stohs-Krause, NET News)
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January 2, 2013 - 6:30am

A Nebraskan is infected with HIV every three days; nationally, it’s every 11 minutes. A vaccine for the virus will be tricky to come by, if it’s possible at all. But a researcher from the University of Nebraska-Lincoln is looking into a method of prevention that would be easy, cheap and long-term – and that relies on a feature of a common grocery item.

On a recent, crisp winter day at a Lincoln grocery store, shoppers perused dozens of different kinds of yogurt: harvest peach, strawberry, Greek, Greek strawberry … the list goes on and on. Yogurt’s a healthy snack for numerous reasons; it’s high in calcium, protein, magnesium and potassium, to name a few.  And if a University of Nebraska-Lincoln professor’s research goes the way he hopes, yogurt could one day also keep you safe from HIV.

It’s part of the research being conducted by Dr. Shi-hua Xiang, professor with the Virology Center at the University of Nebraska-Lincoln. But to understand how novel his approach is – and the potential it holds, if it proves successful – we need a bit of background first.

Courtesy image

Dr. Shi-hua Xiang with the University of Nebraska-Lincoln is looking to use genetically modified lactobacillus to prevent HIV infection; in theory, the bacteria would essentially "trap" and neutralize HIV particles before they could infect the body.

Graphic courtesy of the U.S. Centers for Disease Control

This chart shows how the rate of new HIV infections has stabilized over time.

There’s been lots of talk recently about how to achieve an “AIDS-free generation.” Progress is being made; the global rate of new HIV infections dropped 20 percent in the last decade, and nationally, the rate of new HIV diagnoses has remained relatively stable for the last five or six years, according to the U.S. Centers for Disease Control.

“Even in the high incidence areas, like in Sub-Saharan Africa, we see it dropping every year (by) one or two percent,” said Dr. Charles Wood, director of the Virology Center. “So it’s really hopeful.”

But the numbers aren’t all good: 2.5 million people were still infected with HIV in 2011, and a Nebraskan is infected with HIV every three days. Of course, the easiest solution would be a vaccine – but experts like Dr. Susan Swindells, an HIV researcher at the University of Nebraska Medical Center, say that’s decades away, if it’s possible at all.

Swindells pointed to measles, a virus that’s basically been wiped out through the proliferation of vaccinations. In that case, the vaccine is based on the natural immunity that results from people whose bodies defeated the virus; HIV, however, attacks the immune system itself, so there’s no natural immunity to use as the building block for a vaccine.

Similarly, while a measles virus is the same in Omaha as in South Africa as in Japan, HIV is a different story, Wood from the Virology Center said. The virus mutates rapidly, and so even within specific populations there can be numerous strains.

And Swindells said existing animal test subjects don’t work very well for testing HIV.

“A chimpanzee you can infect with HIV, but they don’t get AIDS, and they don’t get sick,” she said. “There’s only so much you can test.”

Xiang with the Virology Center acknowledged the complications.

“HIV is very challenging to us, scientifically,” he said. Given the difficulties of formulating a vaccine, he decided to try something different.

That’s where that grocery store yogurt comes in. Among the nutrients mentioned earlier in the story, it’s also a great source of lactobacillus, or that “good bacteria” touted all over the packaging. That’s what Xiang is focusing his research on: he’s testing a genetically modified version of the bacteria that would essentially act as a decoy, tricking the HIV virus into attacking. But instead of letting the virus then pass into and infect the body, the bacteria trap it.

“So you can actually neutralize the HIV virus,” he explained.

The bacteria, which has a fairly short shelf-life, then naturally passes from the body, taking the HIV virus with it.

The modified lactobacillus could be introduced to the body in several different ways, Xiang theorized – including, perhaps, a spoonful of yogurt. The idea is that the modified bacteria would then replicate themselves in the areas where their counterparts already exists – the mouth, the vagina, the rectum – which are also the main points of entry for the HIV virus.

Now, Xiang is still at the beginning; he hopes to have his animal testing completed by the end of the year, and if the bacteria prove successful, quickly move onto human clinical trials. Because Xiang’s approach is so different, animal tests are more helpful.

Several big questions remain: will the bacteria actually colonize? If so, how long will they last? Would you need to get a booster shot, so to speak – and if so, how often?  

“And of course, the question is, ‘How effective it is?’” Wood said. “As you know, (with) HIV, only one single virus can initiate infection. You have to be completely, 100 percent-blocking.”

In contrast to the search for a vaccine, Xiang’s research is part of Swindell’s strategy of choice: end the epidemic by simply interrupting the transmission through prevention and treatment.

Vaccine or no vaccine, HIV is technically a preventable disease, Swindell said. Regular treatment for infected people drops the risk of transmission to 3 percent, and those not infected can take a daily preventative pill and practice safe sex. But she acknowledged that these methods require constant attention and action and can be prohibitively expensive; HIV treatment costs about $1,200 to $1,500 per month, and 40 percent of her patients are uninsured.

“It’s somewhat pie in the sky, because we can’t even get everyone in this country on treatment, and you know, we need to do it in places that are very much more challenging,” she said.

On top of that, the key to getting treated is knowing that you have HIV in the first place. According to the Kaiser Health Foundation, only 40 percent of Americans nationwide have ever been tested for HIV as of 2010. In Nebraska, that number drops to 26 percent.

So for now, the main thing is to just get tested, Wood said – and get treated.

“With that, I think we can hopefully go into the so-called ‘AIDS-free generation,’” he said. “Not necessarily because of a vaccine, (but) because of the effectiveness of treatment as prevention strategy.”



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