Study published by Soligenix on characteristics of ricin A chain

Soligenix, Inc., has announced the publication of an article that details the characteristics of several immunodominant regions of ricin A chain - the antigenic component of Rivax - in the January 2010 edition of Infection and Immunity.

Rivax is the vaccine created by Soligenix to protect against exposure to ricing toxin. Rivax is currently in the Phase 1 human and safety immunogenicity trial evaluation stage and is also being tested through nonhuman primate trials for efficacy.

The Infection and Immunity article, "A Monoclonal Immunoglobulin G Antibody Directed against an Immunodominant Linear Epitope on the Ricin A Chain Confers Systemic and Mucosal Immunity to Ricin,"follows a collaboration between the Wadsworth center of the New York State Department of Health and Soligenix funded in large part by several grants from the National Institutes of Health for the development of Rivax.

Investigators from the study produced and characterized a monoclonal antibody that was directed against a region of the ricin A chain that had previously been known to be highly immunologically stimulatory in human.

The antibody, shown to bind the ricin A chain with high affinity, was capable of neutralizing ricin toxin in a cell-based killing assay.

When administered passively to mice, the antibody was found to be sufficient to protect the animals against both systemic and mucosal ricin challenge.

As a result of this study, the concept that antibodies present in the circulation at the time of toxin exposure protects animals against death and prevents the toxin's effects on mucosal tissues has been further advanced.

This finding is important as ricing is toxic to humans after both ingestion and inhalation. The study also raises the possibility for the use of specific linear determinants on the ricin A chain as markers for protective immune responses in humans.

"These data are important in terms of ricin vaccine development, since they firmly establish that pre-existing serum antibodies directed against linear determinants on the ricin A chain are sufficient to confer both systemic and mucosal immunity to ricin," Nicholas Mantis, Ph.D., Research Scientist IV, Wadsworth Center, and lead author of the study said.

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National Institutes of Health

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