Table 1.
Summary of preclinical efficacy of phage-derived depolymerases.
| Depolymerase name | Animal infection model | Dose regimen | Result | Ref. |
|---|---|---|---|---|
| K. pneumoniae | ||||
| K2 depolymerase | Normal mouse pneumonia and septicemia models | A single dose of 50 μg enzyme or in combination with 1.5 mg/kg gentamicin given 24 h (pneumonia model) or 6 h (septicemia model) post-infection via i.p. injection | The bacteria count, inflammatory cytokine (IL-1ß, IL-10 and TNFα) levels and neutrophil infiltration were significantly reduced in both infection models. Combination treatment caused more bacteria reduction and cytokine downregulation than sole depolymerase treatment. | 29 |
| K64dep | Immunocompromised mouse bacteremia model | A single dose of 18.75 or 150 μg enzyme given 1 or 8 h post–challenge via i.p. injection, respectively | The survival rate was 100% and 12.5% when treatment was given at 1 and 8 h post-infection, respectively. Significant antibacterial effectiveness was yielded by earlier treatment. No toxicity and pathological changes in liver, kidney, and spleen were observed. |
31 |
| K1-ORF34 | Immunocompetent and immunocompromised mouse invasive infection | A single dose of 25 μg enzyme given 30 min post-infection via i.p. injection | The survival rate was 100% in treating immunocompetent mice infected with 3.3 × 103 CFUs bacteria and immunocompromised mice infected with 1.6 × 103 CFUs bacteria. This indicated the antibacterial effects of depolymerases to both models. | 69 |
| Dep_kpv74 | Normal mouse hip infection model | A single dose of 10, 20, or 40 μg enzyme given 0.5 h post-infection via i.p. injection A single dose of 40 μg enzyme given 0.5, 3, or 24 h post-infection via i.p. injection |
The survival rate was 90% (40 μg, 0.5 h group), 80% (10 and 20 μg, 0.5 h groups) and 60% (40 μg, 3 and 24 h groups). A higher dose and earlier treatment can lead to improved treatment outcomes. | 70 |
| P560dep | Normal mouse bacteremia model | A single dose of 50 μg enzyme given 1 h prior to bacterial infection or 1 h post-infection via i.p. injection | 100% and 90% of mice were protected from death in the prevention and treatment groups, respectively, indicating significant prevention effect and antibacterial effect. | 71 |
| Dp42 | Normal mouse bacteremia model | A single dose of 50 μg enzyme given 6 h prior to bacterial infection or 0.5 h post-infection via i.p. injection | 100% of mice were protected from death, indicating significant prevention effect and antibacterial effect. Bacterial load in the mouse organs were significantly reduced. |
72 |
| depoKP36 | Galleria mellonella larvae infection model | A single dose of 2.8 μg depoKP36 given 5 min post-infection, or bacteria pretreated with 280 μg/mL enzyme for 2 h before inoculation via injection into the last proleg | The survival rate at 24, 48, 72 h was 40%, 30%, 20% in the post-infection treatment group and 77%, 47%, 43% in the pre-infection treatment group, respectively. Pretreatment of bacteria with depolymerase showed an increased survival rate compared to post-infection treatment. | 73 |
| Dep_kpv79 Dep_kpv767 | Normal mouse sepsis and hip infection model | A single dose of 50 μg enzyme given 0.5 h post-infection via i.p. injection | 80%–100% of animals were protected against death. | 74 |
| Dep622 DepS8 | G. mellonella larvae infection model | A single dose of 2 μg Dep622 or DepS8 simultaneously given at the same time of bacteria inoculation via injection into the hemocoel | ∼90% and ∼70% of larvae inoculated with 3 × 105 and 3 × 106 CFU bacteria survived within 5 days, respectively. The antibacterial efficacy was negatively correlated to the severity of infections. | 75 |
| A. baumannii | ||||
| Dpo71 | G. mellonella larvae infection model | A single dose of 5 μg Dpo71 or in combination with 1 μg colistin given 0.5 h post-infection via injection into the last right proleg | 40% and 80% of infected worms were rescued from the Dpo71-alone treatment and combination treatment, respectively. The antibacterial effect was significantly improved in combination treatment compared with the single treatments. | 11 |
| Tailspike protein of φAB6 phage | Zebrafish infection model | A single dose of 20 μg enzyme given 0.5 h post-infection via injection into cloaca | 80% of zebrafish survived within 4 days. No toxicity was observed. |
30 |
| K2 depolymerase | G. mellonella larvae infection model and immunocompromised mouse sepsis model | A single dose of 0.25, 0.5, and 3 μg per larva given 30 min post-infection, or bacteria pretreatment for 2 h before inoculation via injection into the penultimate right proleg A single dose of 50 μg enzyme per mouse given 1 h post-infection via i.p. injection |
The larvae survival rate was significantly increased in a dose-dependent and dosing time-dependent manner. Treated with 0.25, 0.5, and 3 μg enzyme, 53%, 69% and 88% of larvae survived in the pretreatment group, and 15%, 56% and 70% of larvae survived in the post-infection treatment group. 60% of enzyme-treated mice survived. The inflammatory factors (TNF-α and IL-6) were significantly reduced. |
64 |
| Dpo48 | G. mellonella larvae infection model, normal and immunocompromised mouse sepsis model | A single dose of 5 μg Dpo48 given 5 min post-infection, or bacteria pretreated with 50 μg/mL enzyme for 1 h before inoculation via injection into the last proleg A single dose of 50 μg enzyme per mice given 2 h post-infection via i.p. injection |
93% and 26% of larvae survived in the pretreatment group and treatment group within 3 days, respectively. Pretreatment of bacteria with depolymerase showed an increased survival rate compared to post-infection treatment. 100% of mice were protected from death. No significant differences in blood biochemical indicators and histopathological changes in the liver, spleen, lung and kidney were observed. |
76 |
| Dp49 | Normal mouse bacteremia infection | A single dose of 50 μg enzyme given 0.5 h post-infection via i.p. injection | 100% of mice were protected from death within 96 h. The bacterial loads from organs such as liver, spleen, and lungs all significantly decreased. |
77 |
| E. coli | ||||
| EndoE (K1E) | Neonatal rat gastrointestinal colonization-induced bacteremia model | 20 μg enzyme given by i.p. injection on Days 1, 2, 3, 4, and 5 post-infection; A single dose of 20 μg enzyme given on Days 1 or 3 post-infection via i.p. injection; A single dose of 0.125–20 μg enzyme given on Day 1 post-infection via i.p. injection | EndoE prevented the death and invasion of bacteria from the gastrointestinal tract into the bloodstream from the first dose. A single dose of depolymerase was sufficient to produce a therapeutic effect comparable to that of multiple doses. Single-dose treatment on Day 1 was more effective than that on Day 3. Earlier treatment with depolymerase yielded a better antibacterial efficacy. The minimal dose of 0.25 μg prevented the death of at least 80% of rats. |
27,78 |
| K1F, K1H, K5, K30 gp41, K30 gp42 depolymerases | Normal and immunocompromised mouse systemic infection model | Normal: 0, 2, 5, or 20 μg enzyme given within 0.5 h post-infection via injection into the right thigh; 20 μg enzyme given 8 h post-infection via injection into contralateral thigh; 20 μg K1E, 2 μg K1F and 2 μg K1H given immediately via i.p. and i.m. injection Immunocompromised: 20 μg enzyme given immediately or 8 h post-infection via i.m injection |
For normal mice, they were rescued in a dose-dependent manner. Delayed treatment with K1F, K1H and K5 enzymes resulted in 50%–60% survival compared to 90%–100% in immediate treatment. K1E significantly improved survival rate via i.p. injection compared with i.m. injection; K1F enzyme showed the opposite pattern; K1H yielded similarly low rescue rates for both routes. No toxicity was observed. For immunocompetent mice, immediate treatment was superior to delayed treatment for all enzymes. |
79,80 |
| Dep6 | Normal mouse systemic infection model | A single dose of 30 μg Dep6 given 3 h prior to infection, simultaneously with bacteria, and 3 h post–challenge | The survival rates were 33%, 83%, 100% in the post-infection treatment group, simultaneous treatment group and pretreatment group, respectively, indicating a dosing time-dependent manner. No toxic effects were observed. |
81 |
| P. aeruginosa | ||||
| LKA1gp49 | G. mellonella larvae infection model | A single dose of 5 or 50 μg/mL given 15 min post-infection, or bacteria pretreated with 5 μg/mL enzyme for 1 h before inoculation via injection into the hindmost proleg | 20% of larvae survived after 72 h in the treatment group, independent of LKA1gp49 concentration. 35% of larvae survived after 72 h in the pretreatment group. Pretreatment of bacteria with depolymerase showed an increased survival rate compared to post-infection treatment. | 82 |
| S. enterica | ||||
| P22sTsp | Chicken gastrointestinal tract infection model | 3 doses of 30 mg P22sTsp given 1, 18 and 42 h (protocol 1) or 18, 42 and 66 h (protocol 2) via oral garage. | A significant reduction of Salmonella in the cecum, liver and spleen in Protocol 1 but not in Protocol 2. Significant antibacterial effectiveness was yielded by earlier treatment. | 28 |
| S. aureus | ||||
| DA7 | Murine model of fracture-related infections | A single dose of 50 μg equimolar enzybiotics (M23, GH15, DA7) or in combination with 200 μg gentamicin via irrigation and 110 mg/kg vancomycin via s.c. | Enzybiotics alone did not significantly reduce overall CFU levels in soft tissue and implant but did so in combination with classical antibiotics. The antibacterial effect was significantly improved in combination treatment compared to the single treatments. | 83 |