Development and use of an established cell line of the leafhopper Circulifer tenellus to characterize Spiroplasma citri-vector interactions

A continuous cell line of embryonic origin from the leafhopper Circulifer tenellus, CT 1, was established using a protocol modified from thrips cell culture. The line was used to develop an in vitro model to examine the mode of entry of the plant pathogenic mollicute Spiroplasma citri into insect host cells. Confluent monolayers were achieved in 5-6 months using a simple medium developed for maintaining established leafhopper cell lines. The newly established CT 1 line, and that of another leafhopper, Nephotettix cincticeps, were exposed to S. citri and examined by electron microscopy. S. citri was found to cytadhere and to be present in apparent invaginations of the host cell membranes of cell lines of both leafhopper species, supporting the hypothesis that this pathogen enters its insect host via endocytosis.