Ricin chain A. This vaccination is effective for several months due to the body's production of antibodies to the foreign protein. In 1978 Bulgarian defector Vladimir Kostov survived a ricin attack similar to the one on Georgi Markov, probably due to his body's production of antibodies. When a ricin-laced pellet was removed from the small of his back it was found that some of the original wax coating was still attached. For this reason only small amounts of ricin had leaked out of the pellet, producing some symptoms but allowing his body to develop immunity to further poisoning. The seeds of
Bulgarian umbrella Vladimir Kostov the same year in the Paris "Métro". The poison used in both cases was ricin. Both assassination attempts are believed to have been organized by the Bulgarian Secret Service of the time of the Cold War with the assistance of the KGB. Such an umbrella was intended to be used in the assassination of Pallo Jordan and Ronnie Kasrils by the South African Civil Cooperation Bureau death squad. These two cases inspired the 1980 French film "Le Coup du parapluie" ("The Umbrella Coup") directed by Gérard Oury and starring Pierre Richard, and Bulgarian writer Stefan Kisyov's novel "The