Ultrastructural study of acquisition and retention of potato leafroll luteovirus 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 rapid translocation of the virus through the intestine into the haemocoel. Indeed, viral particles could be observed in the intestinal epithelial cells, then in the haemocoel, 4 and 8 h, respectively, after their arrival in the lumen of the alimentary canal. However, the virus accumulated in the intestinal epithelial cells. In these cells, the first viral particles were seen enclosed in isometric or tubular isolated vesicles; a few hours later, they were present in tubular aggregated vesicles and also in lysosomes or multivesicular bodies. After a 40 h acquisition period, all studied intestinal epithelial cells exhibited high numbers of viral particles which were consistently distributed throughout these cell structures. When aphids were removed from viral source, viral particles were detected in intestinal lumen for a further three days and in intestinal epithelial cells for a total of eight days. Virus content in these cells began to decrease from the second day. Areas with tubular aggregated vesicles were maintained for seven days following aphid removal from viral source, but progressively became smaller and fewer. The accumulation and the persistence of PLRV in the intestine are discussed.