Fig. 5: Phage immune neutralization (PIN) assay.

a Schematic overview of the assay’s methodology (T^C: control titer; T^5’: titer after 5 min of serum-phage co-incubation; T^30’: titer after 30 min of serum-phage co-incubation). b Chronological phage immune neutralization (PIN) activity against phage ISP of ten patient sera collected before, during and after phage therapy. The evolution over time of the PIN activity against phage ISP is shown. Serum PIN activity is shown as % phage titer loss (compared to a pre-PT control serum) after incubation of phage ISP with sequential serum samples for 30 min. PIN activity appeared during the fifth week of PT initiation and had disappeared in a one-year post re-transplantation serum sample. Data are presented as mean values with error bars representing the standard deviation of the means. Each serum sample was tested on at least three independent occasions: six times for the 24-12-18 sample, four times for the 07-01-19 and 18-01-19 samples, and three times for all the other samples. c, d Persistent biological immunosuppression over the course of PT is illustrated through repeated quantification of the patient’s blood lymphocytes (normal values 4.0–10.5 × 10³ cells/microliter) and gamma-globulins (normal values 7.0–15.0 grams/liter). Source data are provided as a Source Data file.