Scientists have found a way to develop a vaccine that protects against both viral pox and bacterial anthrax and is likely to be more effective than separate vaccines used so far, the journal Science reported.
The vaccine against smallpox, a viral disease that killed 30% of of its victims before it was finally removed in the 70s, it was highly effective in a single dose.
But the vaccine was a live virus called wakcinia that had serious side effects such as encephalitis and heart inflammation, sometimes resulting in death. It was not recommended for various risk groups, such as patients without the body’s immune defense or with eczema – approximately 1 population. Officially, only two laboratories in the world – one in the US and one in Our Country – have Variola major pox viruses.
The anthrax vaccine is also difficult to use. Made from protein fragments called Protective Antigen (PA) harvested from Bacillus anthracis bacteria, the vaccine is a series of 5 or 6 injections over 18 months and requires an annual booster. It is also not stable, it can be stored on a shelf for about 4 years, which means that storage for emergencies is expensive. In addition, the smallpox vaccine is fast enough to provide protection for days after exposure to the pathogen; laboratory studies suggest that this is not the case with the anthrax vaccine.
Over the past decade, scientists led by Liyanage Perera of the National Cancer Institute in the US have been developing what they said was a safer vaccine against smallpox. They did this by equipping the vaccinia with the gene that encoded the interleukin IL-15, a signaling molecule that stimulated the immune system and helped the virus clear away from the body faster when it triggered a strong response. The team’s latest work showed that the new smallpox vaccine does not kill immunocompromised mice, as does the standard vaccine, and that monkeys offer long-term protection against the monkey pox virus, the best animal model of human pox.
In their current research, scientists took a step forward: they incorporated the gene encoding PA, the protein unit of the current anthrax vaccine, into the vaccinia. According to a report published in the Proceedings of the National Academy of Sciences (PNAS), the team shows that by giving rabbits two doses of the vaccine 28 days earlier, they were protected against a lethal dose of inhaled anthrax bacteria. In an additional study in mice, the new vaccine not only produces more antibodies to PA than usually used, but does so much faster, presumably due to the action of IL-15. Also, unlike a traditional vaccine, it can be stored in a dry form for possibly decades. Additional research suggests that the vaccine is also protective against smallpox, Perera says (PAP).