Chlamydia-like organisms in ctenidia and mantle cells of the Japanese oyster Crassostrea gigas from the French Atlantic coast

Grossly visible lesions of the ctenidia and occasional mortalities in Japanese oyster Crassostrea gigas from the Atlantic French coast were reported in 1992-1993. From August 1992 to March 1993, 235 living oysters were collected to determine the cause of tissue lessions and mortalities. Microscopical examination of fixed, stained sections revealed that 53.2% of these oysters had ctenidia and mantle lesions associated with irregular baseophilic and Feulgen positive cytoplasmic inclusions bodies. Ultrastructurally, the infectious agent was a chlamydia-like organism. Indirect fluorescent and peroxidase conjugated antibody tests suggested that this agent might share common antigens with the procaryotic agent Chlamydia psittaci, strain ovis.