CHICAGO, Aug. 28 (Xinhua) -- Researchers at Washington University School of Medicine in St. Louis and VaxNewMo, a St. Louis-based startup, have produced and tested, in mice, a vaccine that protects against a worrisome superbug: a hypervirulent form of the bacteria Klebsiella pneumoniae.
The researchers genetically modified a harmless strain of E.coli, converting it into tiny biological factories capable of churning out the protein and sugars needed for the vaccine. Then they used another bacterial enzyme to link the proteins and sugars together.
To test the vaccine, the researchers gave groups of 20 mice three doses of the vaccine or a placebo at two-week intervals. Then they challenged the mice with about 50 bacteria of either the K1 or the K2 type Klebsiella, which are responsible for 70 percent of the infection cases.
Of the mice that received the placebo, 80 percent infected with the K1 type and 30 percent infected with the K2 type died. In contrast, of the vaccinated mice, 80 percent infected with K1 and all of those infected with K2 survived.
"We are very happy with how effective this vaccine was," said the study's first author Mario Feldman, an associate professor of molecular microbiology at Washington University and a co-founder of VaxNewMo. "We're working on scaling up production and optimizing the protocol so we can be ready to take the vaccine into clinical trials soon."
Klebsiella pneumoniae causes a variety of infections including rare but life-threatening liver, respiratory tract, bloodstream and other infections. Little is known about how exactly people become infected, and the bacteria are unusually adept at acquiring resistance to antibiotics.
Hypervirulent strains of Klebsiella caused tens of thousands of infections in China, Taiwan and South Korea last year, and the bacteria are spreading around the world. About half of people infected with hypervirulent, drug-resistant Klebsiella die.
The goal is to get a vaccine ready for human use before the hypervirulent strains start causing disease in even larger numbers of people, the researchers said.
Details of the prototype vaccine were published online on Tuesday in Proceedings of the National Academy of Sciences.
