Scientists have developed the first vaccine shown to protect nonhuman primates from melioidosis, an infection caused by Burkholderia pseudomallei. The results, published in Nature Communications, are described as a key step toward human clinical trials. The corresponding author, Lisa Morici of Tulane University School of Medicine, said the team hopes to advance the vaccine soon to human trials.
Morici noted that this bacterium can cause an aggressive form of pneumonia within 72 hours that can obliterate the lung, but animals protected by the vaccine showed no lung damage; their lungs were completely normal. The vaccine was effective against aerosolized bacteria, which the team calls the most lethal and difficult form to protect against.
The bacteria are most common in Southeast Asia and northern Australia and have recently been found in the Gulf Coast region, Puerto Rico and the US Virgin Islands. They can enter open wounds, be ingested, or be inhaled. There are an estimated 165,000 cases worldwide each year, and mortality ranges from 20-50 percent because the bacteria are naturally resistant to many antibiotics and relapse can occur after months of therapy. The organism is a Tier 1 Select Agent, so protecting people is a priority.
The vaccine uses outer membrane vesicles (OMVs), nanoparticles shed by bacteria that trigger immune responses. Tests on human immune cell samples produced antibody and T cell responses that suggest the vaccine could work in people. Development took more than a decade and required international collaboration. The research teams included:
- Tulane University
- Northern Arizona University
- University of California, Irvine
- Charles Darwin University
Researchers say they hope to move the vaccine into human trials and to protect people from this dangerous disease.
Difficult words
- melioidosis — a severe infectious disease caused by bacteria
- aerosolize — to make into tiny particles in the airaerosolized
- obliterate — to destroy completely or remove all traces
- outer membrane vesicle — small particles from bacterial outer cell surfaceouter membrane vesicles
- relapse — return of an illness after initial recovery
- mortality — the rate of death in a group
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- What benefits and risks should researchers consider before starting human trials of this vaccine?
- How might the appearance of this bacterium in new regions change public health priorities?
- Why is international collaboration important for developing vaccines against diseases like this one?
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