[Delta agent]

Abstract

Discovered in 1977 by Rizetto and his collaborators, agent delta is today considered as a virus entirely distinct from the H/B virus. This small RNA virus, transmissible to primate and to man, is defective: its replication in the liver is only possible when there is a pre-existing or simultaneous infection by the H/B virus with HBs antigenaemia. Its clinical importance appears very great as agent delta is very pathogenic to the liver: super-infection by this virus of a patient infected by the H/B virus explains a good number of cases of acute fulminant hepatitis and of chronic active hepatitis developing towards cirrhosis, disorders attributed in the past solely to the hepatitis B virus.