If he is correct, the researcher, Bertram Jacobs, may be able to create not only a vaccine that can cure smallpox infections in their early stages, but a powerful tool for fighting a host of other viral pathogens, including HIV.
Jacobs has received a $1 million grant from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), to develop an effective post-exposure vaccine for smallpox. The research is one of ten projects funded under Project Bioshield, which gives federal agencies new tools to accelerate research on medical countermeasures to safeguard Americans against chemical, biological, radiological or nuclear attack.
The idea for the vaccine comes from Jacobs and his team’s discovery of a gene that gives pox viruses uncanny ability to camouflage themselves from mammalian immune systems. The ability to stay hidden allows the smallpox virus, in particular, time to grow and multiply to the point of causing devastating disease before the immune system detects it and attempts to mount a counter-attack.
Jacobs’ idea for a post-exposure vaccine is to strengthen the immune response to the vaccinia virus by completely eliminating the viral gene that allows pox viruses to hide. The more visible the vaccinia virus is to the immune system, the stronger the immune response should be and the better the body should be able to fight off a smallpox infection.
The gene that Jacobs has isolated is a special adaptation of pox viruses that appears to help the viruses hide double-stranded RNA, a form of RNA that only viruses produce and that animal immune systems have learned to recognize.
Due to the extreme dangerousness of the smallpox virus, the effectiveness of the vaccine cannot actually be tested through clinical trials on humans. Instead, the vaccine is tested on mice and other animal models, using viruses closely related to smallpox that are lethal to those animals.
“We’re testing with vaccinia and mousepox in lab mice, and in dormice with monkeypox. These are good model systems – if we can protect against mousepox in mice, then we have a high level of certainty that the vaccine will be able to protect against smallpox in humans,” Jacobs said.
“Since you can’t test in people, the FDA’s animal efficacy rule applies. If you can show efficacy in several animal models, then you can presume efficacy in humans, if it is for a disease that you can’t ethically expose people to in trial. The vaccine will go through safety studies in humans, though.”