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
1978 Balkan Bulgarian Tupolev Tu-134 crash 1978 Balkan Bulgarian Tupolev Tu-134 crash The 1978 Balkan Bulgarian Tupolev Tu-134 crash was an accident that occurred on 16 March 1978, when a Balkan Bulgarian Airlines Tupolev Tu-134 airliner on an international flight from Sofia, Bulgaria, to Warsaw Airport, Poland crashed. On departure from Sofia, the aircraft was climbing to , but at it turned on a heading of 050. It turned again to 270 then began an abnormal descent. The aircraft crashed near the village of Gabare, 130 km northeast of Sofia. All 73 on board died. It was never established what the nature of the emergency was