Polyamine

Cells were seeded with fresh medium with 2% serum for all drug treatments. Following overnight attachment, cells were treated and incubated at 37°C for times indicated below. Difluoromethylornithine (DFMO; TargetMol) was diluted to a 100-mM solution in sterile water and stored at 4°C. For DFMO, cells were treated and incubated for 96 h at 1 mM. N11-Diethylnorspermine (DENSpm; Santa Cruz Biotechnology) was diluted to 10 mM in sterile water and stored at 4°C. For DENSpm, cells were treated and incubated for 24 h at 100 mM. GC7 (Cayman Chemical) was diluted to a 100-mM solution in sterile water and stored at −20°C. For GC7, cells were treated for 24 h at 500 mM along with 500 μM aminoguanidine (Sigma-Aldrich). Ribavirin (VWR) was diluted to 100 mM in sterile water and stored at −20°C. For Ribavirin, cells were treated and incubated for 4 h at 400 mM. Polyamines (Sigma-Aldrich) were added to cells at the time of infection at 10 mM unless otherwise indicated. For infections, all drug treatments were performed at the time of infection unless otherwise indicated. For persistently infected experiments, drugs were continually supplemented onto cells with fresh medium with 2% serum upon collection of viral supernatants.

Poly‐l‐lysine (Br⁻; mean DP by viscometry 115), poly‐l‐arginine (Cl⁻; DP 61), poly‐l‐histidine (Cl⁻; DP 106), poly‐l‐glutamate (Na⁺; DP 240), boric acid, lead nitrate, l‐ascorbic acid, dehydro‐l‐ascorbic acid, sugars, alditols, myo‐inositol, polyamines, l‐lysine and buffer components were all from Sigma–Aldrich (Dorset, UK).

Bacterial strains and plasmids used in this study are shown in Table 6. The primers used for qPCR analyses and construction of gene knockouts are listed in Table S3. P. aeruginosa and Escherichia coli strains were grown in lysogeny broth (LB) at 37°C with agitation (250 rpm). E. coli strain DH10B was used as a host for cloning experiments.
Dendrimers were synthesized and purified as described (19 (link), 42 (link)). Polymyxin-B, polyamines, and chemicals were purchased from Merck-Sigma (Switzerland).

The seeds were sterilized by washing them with 95% ethanol. Except where noted in the text, they were plated on half-strength buffered Linsmaier and Skoog medium containing micro- and macronutrients, vitamins, and 1.5% sucrose (Caisson Laboratories, North Logan, UT, USA) that was supplemented with 1.5% agar type E (Sigma-Aldrich, St. Louis, MO, USA) and polyamines (Sigma-Aldrich) as required. The seedlings were stratified for 2–8 d and grown in either a Conviron TC16 growth chamber or an Enconair (now BioChambers, Winnipeg, Manitoba, Canada) Controller 6000 growth chamber for each experiment. Both chambers were set at 22 °C and a 16h light/8h dark cycle, and the light intensity was 50–70 μmol m^–2 s^–1 and provided by cool-white fluorescent bulbs (Grainger, Lake Forest, IL, USA).