A basic approach towards the development of bioelectric bacterial biosensors for the detection of plant viruses.
There is a growing need for virus sensors with improved sensitivity and dynamic range for disease diagnosis, pharmaceutical research, agriculture and homeland security. Membrane-engineered animal cells bearing antibodies against viral antigens have been previously used for biorecognition biosensors for the ultrarapid (3 min), sensitive (1 ng/ml) detection of plant viruses, such as the cucumber mosaic virus. We here report a new approach for the construction of cell-based sensors for virus detection, based on membrane (antibody)-engineered bacteria. The novel method was applied for the detection of tobacco mosaic virus (TMV) and cherry leaf roll virus (CLRV) using sensors containing modified Escherichia coli XL-1Blue MRF' bacteria. E. coli membranes have been engineered with electro-inserted, virus-homologous antibodies. The detection principle was based on the measurement of changes in the bacterial membrane potential as a result of virus-antibody binding. After optimization of the membrane-engineering process, the virus detection limit for TMV and CLRV with the bacteria-based biosensor system was 1 pg/ml, representing a 1000-fold improvement over currently available methods. Although the novel biosensor is still in its proof-of-concept stage of development, its sensitivity and speed (assay time: 60-100 s) could make it a very promising tool for high throughput, field-based virus screening.