title: Prophage lysin Ply30 protects mice from Streptococcus suis and Streptococcus equi subsp. zooepidemicus infections.
abstract: Streptococcus suis and Streptococcus equi subsp. zooepidemicus are capable of infecting humans and various animals, causing significant problems for the worldwide swine industry. As antibiotic resistance has increased, lysosomal enzymes encoded by phages have shown potential for use against pathogenic bacteria. In this study, a novel bacteriophage lysin, Ply30, encoded by the S. suis prophage phi30c, was recombinantly expressed and purified. Ply30 showed high bacteriolysis activity on S. suis and S. equi subsp. zooepidemicus in vitro. The ratio of the optical density at 600 nm (OD600) with treatment versus the OD600 with no treatment for most tested S. suis and S. equi subsp. zooepidemicus strains decreased from 1 to <0.3 and <0.5, respectively, within 1 h. The results of plate viability assays showed that treated bacteria suffered a 1- to 2-log decrease in CFU within 1 h. The optimal concentration of Ply30 was 50 μg/ml, and the optimal pH was 7. Moreover, Ply30 maintained high activity over a wide pH range (pH 6 to 10). The MICs of Ply30 against Streptococcus strains ranged from 16 to 512 μg/ml. In vivo, a 2-mg dose of Ply30 protected 90% (9/10 mice) of mice from infection with S. equi subsp. zooepidemicus and 80% (8/10 mice) of mice from infection with S. suis. Seven days after lysin Ply30 treatment, bacterial loads were significantly decreased in all tested organs and blood compared with those at 1 h postinfection without Ply30 treatment. Ply30 showed in vitro and in vivo antimicrobial efficiency and protected mice against two kinds of bacterial infections, indicating that Ply30 may be an effective therapeutic against streptococci.
authors.affiliation: Key Lab of Animal Bacteriology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, People's Republic of China; OIE Reference Lab for Swine Streptococcosis, Nanjing, People's Republic of China.
authors.forename: Fang
authors.initials: F
authors.lastname: Tang
authors.affiliation: Key Lab of Animal Bacteriology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, People's Republic of China; OIE Reference Lab for Swine Streptococcosis, Nanjing, People's Republic of China.
authors.forename: Dezhi
authors.initials: D
authors.lastname: Li
authors.affiliation: Key Lab of Animal Bacteriology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, People's Republic of China; OIE Reference Lab for Swine Streptococcosis, Nanjing, People's Republic of China.
authors.forename: Haojin
authors.initials: H
authors.lastname: Wang
authors.affiliation: Key Lab of Animal Bacteriology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, People's Republic of China; OIE Reference Lab for Swine Streptococcosis, Nanjing, People's Republic of China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Ma
authors.affiliation: Key Lab of Animal Bacteriology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, People's Republic of China; OIE Reference Lab for Swine Streptococcosis, Nanjing, People's Republic of China.
authors.forename: Chengping
authors.initials: C
authors.lastname: Lu
authors.affiliation: Key Lab of Animal Bacteriology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, People's Republic of China; OIE Reference Lab for Swine Streptococcosis, Nanjing, People's Republic of China daijianjun@njau.edu.cn.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Dai
mesh_terms: D000825:Animal Structures / Q000382:microbiology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000302:isolation & purification / Q000378:metabolism; D001433:Bacteriolysis; D001769:Blood / Q000382:microbiology; D015169:Colony Count, Microbial; D004195:Disease Models, Animal; D010450:Endopeptidases / Q000008:administration & dosage* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D051379:Mice; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D039002:Prophages / Q000201:enzymology* / Q000235:genetics; D013290:Streptococcal Infections / Q000188:drug therapy*; D018502:Streptococcus equi / Q000187:drug effects* / Q000502:physiology; D017011:Streptococcus suis / Q000187:drug effects* / Q000502:physiology; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D010450:Endopeptidases; C001143:endolysin