AVI BioPharma Inc.'s results from four programmes show that AVI has successfully used its NeuGene antisense technology to combat the Ebola and Marburg viruses and to interrupt the cellular mechanism that ricin and anthrax toxins employ to induce lethal toxicity. The programmes were partially funded by the United States Department of Defence (DoD) in collaboration with the US Army Medical Research Institute of Infectious Diseases (USAMRIID) at Fort Detrick.
Ebola virus studies in three animal species have been conducted at USAMRIID. The studies provided evidence of robust efficacy in multiple experiments conducted on mice, guinea pigs and nonhuman primates. Previous attempts by USAMRIID to treat Ebola virus with other technologies have demonstrated few successes in treating all three species, informs a company release.
Using Ebola virus mouse and guinea pig models, AVI targeted six of the seven Ebola virus genes with multiple compounds. The compounds were used as single agents and in combinations in prophylactic and therapeutic models.
The release further states that AVI's NeuGene compounds were well-tolerated, from a safety perspective, by the NeuGene-treated nonhuman primates. In experiments designed to evaluate NeuGene antisense agents targeting the Marburg virus, the guinea pig animal model was used, and the experimental design was similar to the studies on Ebola virus. More than 20 antisense compounds directed against multiple Marburg genes as single agents have been tested first in vitro, as well as in both prophylactic and therapeutic regimens in a guinea pig model of Marburg virus.
Ricin is an enzymatic toxin from the caster bean. It is composed of two peptides, one responsible for cell entry and the other for toxicity. Once inside the cell, the ricin enzyme cuts ribosomal RNA at the crucial initiation site. Without a functional initiation site, the cell cannot produce proteins, and cell death is rapid.
AVI's approach was to use NeuGene antisense agents designed to block the ricin target site on ribosomal RNA, and therefore interfere with ricin enzymatic activity.
Anthrax is caused by toxins produced after infection with Bacillus anthracis. The anthrax lethal toxin (LT) activates host proteins that go on to trigger the apoptotic or cell-death pathway in cells that are infected. The approach that AVI and USAMRIID have taken to counter this cycle was to target host proteins that the anthrax toxin uses. In this manner, if the infected cells are inhibited from expressing the anthrax target, then apoptosis will not be induced and cell death will be reduced or prevented.