Lombardi and co-workers compared the performances of anti CD22 single chain variable fusion constructs/scFv to identify novel recombinant single chain antibodies showing nanomolar affinity for the CD22 antigen able to deliver, either Saporin or Pseudomonas aeruginosa PE40 bacterial-derived toxin, to tumor cells and found comparable cytotoxicities between the plant or bacterial derived ITxs (see the section below) [91,101]. Here, CD22 is linked to neoplasm.