ULTRASTRUCTURAL-STUDY OF ACQUISITION AND RETENTION OF POTATO LEAFROLLLUTEOVIRUS IN THE ALIMENTARY CANAL OF ITS APHID VECTOR, MYZUS-PERSICAE SULZ

The chronology of PLRV acquisition and retention by Myzus persicae was investigated using electron microscopy. Examination demonstrated a ra pid translocation of the virus through the intestine into the haemocoe l. Indeed, viral particles could be observed in the intestinal epithel ial cells, then in the haemocoel, 4 and 8 h, respectively, after their arrival in the lumen of the alimentary canal. However, the virus-accu mulated in the intestinal epithelial cells. In these cells, the first viral particles were seen enclosed in isometric or tubular isolated ve sicles; a few hours later, they were present in tubular aggregated ves icles and also in lysosomes or multivesicular bodies. After a 40 h acq uisition period, all studied intestinal epithelial cells exhibited hig h numbers of viral particles which were consistently distributed throu ghout these cell structures. When aphids were removed from viral sourc e, viral particles were detected in intestinal lumen for a further thr ee days and in intestinal epithelial cells for a total of eight days. Virus content in these cells began to decrease from the second day. Ar eas with tubular aggregated vesicles were maintained for seven days fo llowing aphid removal from viral source, but progressively became smal ler and fewer. The accumulation and the persistence of PLRV in the int estine are discussed.