Treating rabies in humans who have been bitten by a rabid animal is only successful if the person gets medical help early on, before the virus gets into the central nervous system. Otherwise it is almost always fatal.
But researchers have tested a new treatment in mice that appears to cure the disease, even after the virus has spread to the brain.
“Basically, the best way to deal with rabies right now is simple: Don’t get rabies,” says study co-author Biao He, a professor of infectious diseases in the University of Georgia College of Veterinary Medicine. “We have vaccines that can prevent the disease, and we use the same vaccine as a kind of treatment after a bite, but it only works if the virus hasn’t progressed too far.
“Our team has developed a new vaccine that rescues mice much longer after infection than what was traditionally thought possible,” he adds.
In their mouse experiments, the animals were exposed to a rabies strain that usually reaches the brain within three days. After six days, the mice begin to show signs that the infection is fatal.
But half of mice treated with the new vaccine were saved in the trial, even after they showed symptoms of rabies on day six.
“This is the most effective treatment we have seen reported in the scientific literature,” He says. “If we can improve these results and translate them to humans, we may have found one of the first useful treatments for advanced rabies infection.”
He and his colleagues used the vaccine by inserting a protein from the rabies virus into another virus known as parainfluenza virus 5, or PIV5. PIV5 causes upper respiratory infections in dogs but is harmless to humans.PIV5 carries the rabies protein to the immune system so antibodies are created to fight off the virus.
“This is only the beginning of our work,” He says. “While these preliminary results are very exciting, we are confident that we can combine this new vaccine with other therapies to boost survival rates even higher and rescue animals even when symptoms are severe.”
Apart from being very effective in saving the infected mice, the researchers note their vaccine is safer than best current treatment in mice, which uses a weakened version of the rabies virus.
“It doesn’t matter how we weaken the current vaccine, the virus inside it is still rabies,” says study co-author Zhen Fu, a professor of pathology in the college. “That is not a concern with our PIV5 vaccine.”
The researchers plan to refine their vaccine’s design and move into more advanced animal trials soon.
“There is an urgent need in many parts of the world for a better rabies treatment, and we think this technology may serve as an excellent platform,” He says. “Ultimately, we just want to try to save more lives.”
Rabies is transmitted mostly by the bites of wild animals such as bats, raccoons, and skunks, according to the Centers for Disease Control and Prevention. Signs of rabies include flu-like symptoms such as fever and weakness, and the person may develop delirium, confusion, and abnormal behavior. It is important to seek medical attention right away after being bitten by an animal.
