Plants don't need or use B12 and so there isn't any B12 or B12-binding protein in the plant factory to contaminate the Xeragenx IF.
Anti-IF antibodies cause Pernicious Anemia. Xeragenx IF has potential for use in an ELISA kit to diagnose Pernicious Anemia (PA).
Porcine or bovine IF contains contaminating R-binder proteins (Haptocorrin) as well as B12-bound IF (holo-IF) which may cause a loss of specificity of an assay and could lead to failure to detect the presence of vitamin B deficiency. The Schilling Test (gold standard for diagnosing B12 deficiency) was discontinued mainly because of concerns about transmission of bovine spongiform encephalopathy (Mad Cow Disease) via its animal-derived IF. 
Huge volumes of animal gastric fluid have to be purified to obtain even small quantities of IF causing frequent supply issues.
Plants don't need or use B12 and so there aren't any B12-binding proteins or B12-bound IF to contaminate the Xeragenx IF. 
Multiple variables can affect batch to batch consistency from porcine or bovine sources leading to assay sensitivity drift. [1,2]
Recombinant IF can also be made in insect cell cultures but insect cells also use B12, so may be contaminated with R-Binder proteins.
Xeragenx IF has been injected systemically in laboratory animals and found to be useful for imaging the liver.
Zirconium labeled B12-IF is taken up almost exclusively by the liver by attaching to the CD206 receptors found in liver Kupffer cells in an animal study. This forms the basis for exploring Targeted Liver Imaging for malignancy and other serious conditions. 
Any condition in which macrophages accumulate that express the multi-ligand endocytic mannose receptor CD206, is capable of being imaged by Xeragenx's Zr-B12-IF complex.