Figure 3. Cross-competition between trichodysplasia spinulosa–associated polyomavirus (TSV) and Merkel cell polyomavirus (MCV) viral protein 1 (VP1) in serial dilutions of serum samples RTR 108 and RTR 128 from renal transplant recipient patients reactive against TSV VP1 and MCV VP1, the Netherlands. Reactivity was determined by using the VP1 multiplex antibody-binding assay. Samples were preincubated with soluble recombinant glutathione-S-transferase (GST) (black line), GST-MCV VP1 (red line), or GST-TSV VP1 (blue line). Values are median fluorescent intensity (MFI) for seroreactivity against TSV VP1 (A and B) or MCV VP1 (C and D).