Researchers are recruiting healthy volunteers for a Phase I clinical trial (PlaVac) to test a new candidate vaccine against plague, an extremely severe and highly contagious infectious disease re-emerging in some parts of the world.
The vaccine is based on a ChAdOx1 adenovirus viral vector platform and was developed by the Oxford Vaccine Group, part of the University of Oxford.
Forty healthy adults aged 18 to 55 will receive the ChAdOx1 Plague vaccine in order to assess side effects and determine how well it induces protective antibody and T cell responses.
ChAdOx1 is a weakened version of a common cold virus (adenovirus) from chimpanzees that has been genetically changed so that it is impossible for it to multiply in humans. To this virus the researchers have added genes that make proteins from the plague bacterium (Yersinia pestis) called F1 and V antigens, which play an essential role in the infection pathway of the plague bacterium. By vaccinating with ChAdOx1 Plague, the researchers aim to make the body recognize and develop an immune response to these plague proteins that will help stop the plague bacteria from entering human cells and therefore prevent infection. This vaccine does not contain plague bacterium and cannot therefore cause plague following vaccination.
Vaccines made from the ChAdOx1 virus have been given to more than 50,000 people to date, and
have been shown to be safe and well tolerated, although they can cause temporary side effects.
Although for much of the world plague has been eliminated, cases do continue to occur annually in rural areas of Africa, Asia and even in the U.S.
There are three different types of plague: bubonic, pneumonic and septicemic. If left untreated, the bubonic form has a 30 percent to 60 percent fatality rate and the pneumonic form is almost always fatal. Both bubonic and pneumonic plague can develop into a life-threatening infection of the blood called septicemia.
From 2010 to 2015, there were 3,248 cases reported globally, including 584 deaths. A relatively recent epidemic in Madagascar saw 2,119 suspected cases and 171 deaths from August 2017 to November 2017.
“Plague threatened the world in several horrific waves over past millennia, and, even today, outbreaks continue to disrupt communities, ” said Professor Sir Andrew Pollard, Director of the Oxford Vaccine Group. “A new vaccine to prevent plague is important for them and for our health security.”
Probably the most well-known example of plague is the Black Death of the 1300s; this form of the bubonic plague was the biggest global pandemic in history and killed hundreds of millions of people worldwide.
“Although antibiotics can be used to treat plague, many areas experiencing outbreaks are very remote locations,” noted Christine Rollier, Associate Professor of Vaccinology at the Oxford Vaccine Group. “In such areas, an effective vaccine could offer a successful prevention strategy to combat the disease.”
Volunteers for the trial will receive expert follow up for 12 months, before the researchers begin evaluating the data in order to report their findings.
