Oregon scientist develops promising vaccine against TB

The vaccine reduced tuberculosis infections by 70 percent in rhesus monkeys, according to a paper published Monday (January 15) in the journal Nature Medicine.  

Tuberculosis doesn't always make people sick, but it almost always causes severe disease in rhesus monkeys, said Dr. Louis Picker, who developed the vaccine at Oregon Health & Science University.

Though the vaccine has only been given to rhesus macaques, it will eventually be tested in people, Picker said.

His findings offer hope for a disease that sickened more than 10 million people across the globe in 2016, according to the federal Centers for Disease Control and Prevention. Every year, about 2 million die from TB, which affects the lungs but also can attack the kidneys, spine or brain.

"TB is actually the biggest infectious killer now – it's surpassed HIV," Picker said. "It's amazing to me that we haven't seen more of it in this country."

A century ago, TB was a leading cause of death in the United States and Europe. Antibiotics and cleaner living conditions helped stem cases. In 2016, more than 9,000 people were infected with TB in the United States in 2016, the CDC said. The year before, the latest data available, nearly 500 died nationwide.

The bacteria are spread like the flu, largely by coughing. Family and friends who are around the infected person are the most at risk.

Though a vaccine against tuberculosis was developed about a century ago, it's not very effective. It's only given to newborns who are in high-risk areas, and it protects them from severe disease in childhood. It doesn't work well in adolescents or adults, Picker said.

The bacteria also have developed resistance to antibiotics, making that avenue of treatment difficult if not impossible with some people.

"TB is scary now because there's a lot of TB resistance out there," Picker said.

Picker and his crew inoculated 34 rhesus macaques with the vaccine and then later infected them with a virulent strain of tuberculosis. The population was small because the monkeys had to be kept in a special biohazard unit to keep the bacteria from infecting other animals or people.

Scientists who worked with the animals undressed, showered and donned a biohazard suit, mask and respirator before going in and then reversed the process on the way out.

"It's sort like the hot zone," Picker said.

While many vaccine developers expose animals to the infectious particles soon after inoculation, Picker's team waited a year to infect the monkeys to see how the vaccine would work when it wasn't at its peak.

About 40 percent of the vaccinated monkeys didn't show any signs of a TB infection at all. Another 30 percent developed TB but they weren't as sick as the healthiest of the control animals, which weren't vaccinated. All of the 17 control monkeys developed tuberculosis.

That success proves that the concept works, Picker said.

The vaccine uses the same principle behind a promising vaccine that Picker has developed against HIV.

Both are based on a herpes virus – cytomegalovirus – common in Americans and in almost everyone in the developing world.

Typically, it doesn't cause any symptoms in people but it has the unusual characteristic of keeping the immune system's killer T cells on high alert. The virus-based vaccine carries tuberculosis proteins into the body and trains those T cells to recognize tuberculosis and to fight back when the bacteria turn up. 

Using that approach with HIV, Picker was able to protect monkeys from becoming infected with the virus that causes AIDS.

The HIV vaccine will be tested for the first time in humans in 2019, Picker said. After that, he expects the first clinical trial using the TB vaccine.

Source: The Oregonian/OregonLive