Researchers at the University of California, Irvine have identified a potential alternative to the existing smallpox vaccine that can replace the current biodefense stockpile for this lethal virus.
The study, conducted by Philip Felgner and Huw Davies with the Department of Medicine, found that the modified vaccinia virus Ankara (MVA) produced the same antiviral response in human and animal studies as the current smallpox vaccine, Dryvax.
Researchers carried out the study to develop a replacement for the Dryvax vaccine, which causes serious complications in some people.
"Studies have shown MVA to be a much safer vaccine product that takes advantage of modern technology. We are pleased that our advanced analytical methods may help to bring an effective and safer vaccine to the public," Felgner said.
Dryvax and MVA are strain of vaccinia virus, which is related to the smallpox virus. The antibodies created by vaccinia virus infection protect a person against a lethal smallpox infection, making it suitable for use as a vaccine. Unlike smallpox virus, vaccinia creates a very mild infection and is completely safe for healthy individuals.
Although Dryvax was effective but according to today's standards it's manufacturing methods are outdated, and it is also linked to significant risk of adverse reactions for immune-compromised individuals.
Researchers at the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, found MVA as a possible candidate to replace Dryvax.
MVA was first developed in the 1970s and has been given to animal species and humans with little or no adverse side effects.
For the study, researchers applied blood serum samples taken from both humans and animals given the MVA or Dryvax vaccines to 'microarray' chips containing more than 200 vaccinia virus proteins, on which they simultaneously studied how the serum antibodies responded to all the vaccinia proteins.
They found that these antibody responses were similar in both the animal and human subjects regardless whether they were given MVA or Dryvax, suggesting that MVA contains antiviral properties similar to those in Dryvax.
Davies said that this similarity is vital because if a vaccine initiates an immune response in humans that matches the one in animals that are protected against lethal pox viruses, then public health officials will have more confidence that the vaccine will be effective in humans.
"This is particularly important for vaccines against lethal infections like smallpox, where human clinical trials cannot be done," he added.
The results are published in the Journal of Virology.