NEW YORK (Reuters Health) - Mice vaccinated with a human adenovirus expressing a single-chain antibody directed against protective antigen (PA), a key component of Bacillus anthracis lethal toxin, become immune to anthrax within 24 hours of vaccination.
This is much quicker than is possible with existing anthrax vaccines, Dr. Ronald G. Crystal and colleagues from Weill Medical College of Cornell University in New York note in the February issue of Molecular Therapy, journal of the American Society of Gene Therapy.
Currently available anthrax vaccines would be of limited use in a bioterrorism attack because they are active vaccines in which multiple doses are required over several months to elicit protective immunity against anthrax, they explain.
Passive vaccines, like the one Dr. Crystal’s group is developing, on the other hand, shuttle fully formed antibodies directly to the body and immunity is achieved much sooner.
In mice receiving the adenovirus-based anti-PA vaccine, PA-specific serum antibodies were “easily detectable, and these antibodies had neutralizing activity that protected mice from an intravenous lethal toxin challenge when administered as early as 14 days to 1 day prechallenge,” the team reports.
While much more is needed, the researchers envision a scenario where both the passive and active vaccine might be given. “Passive vaccines like this one can lose their effectiveness over time, whereas active vaccines do not,” Dr. Crystal explains in a statement from American Society of Gene Therapy.
“With the passive vaccine you’d get protection that would last a couple of weeks, but that would give you a safety margin while your body is developing more active, long-term immunity,” he added.
Based on their studies to date, Dr. Crystal and colleagues believe that passive immunotherapy with adenovirus-based vectors expressing anti-PA single-chain antibody, either alone or in combination with antibiotics, may be a rapid, convenient, and highly effective strategy to protect against or treat anthrax in a bioterrorism attack.
In the setting of proven infection with B. anthracis, coadministration the passive vaccine with antibiotics may maximize the utility of antibiotic therapy, they suggest. Coadministration “not only would counter the effects of lethal toxin, but also would likely prolong the time frame for effective antibiotic treatment and could additionally reduce the amount of antibiotic therapy required,” they write.
Source: Mol Ther 2005. [ Google search on this article ]
MeSH Headings:Behavioral Sciences: Biological Warfare: Behavioral Disciplines and Activities: Social Problems: Social Sciences: Sociology: War: Drugs, Investigational: Anthropology, Education, Sociology and Social Phenomena: Psychiatry and PsychologyCopyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
