Application of the Phage Lysin Ply5218 in the Treatment of Streptococcus suis Infection in Piglets.

Streptococcus suis (S. suis) is a gram-positive bacterium and zoonotic pathogen. Currently it poses a serious problem in the swine industry due to the emergence of antibiotic-resistant bacteria. Thus, novel antimicrobials against S. suis infections are urgently needed. In the previous study, a cell wall hydrolase or lysin derived from Streptococcus prophage phi5218, termed Ply5218, was identified. This lysin showed strong bacteriolytic activity against S. suis. In the current study, the in vitro data showed that after incubation with pig serum, the bacteriolytic efficacy of Ply5218 declined in a time-dependent manner. The in vivo assays indicated that a Ply5218 triple treatment (6, 24, and 48 h post infection) was effective against various serotypes of S. suis in a murine infection model. This regimen also alleviated streptococcal-induced clinical symptoms in piglets and significantly reduced the bacterial burden and levels of interleukin 6, a proinflammatory cytokine. This study indicates that Ply5218 shows strong antibacterial activity in pigs and has the potential to be used as a treatment for infectious diseases caused by S. suis.

Anti-anaemia efficacy of ß-lactoglobulin hydrolysate-iron complex on iron-deficient anaemic rats.

PURPOSE: The effects of orally administered ß-lactoglobulin hydrolysate-iron complex (ß-LGH-Fe) on haematological and biochemical parameters in anaemic rats were evaluated. Female weaning Sprague-Dawley rats were fed with iron-deficient diet to induce iron deficiency anaemia. After 6 weeks, the obtained anaemic rats were divided into five groups: iron deficiency control group (iron-deficient diet without ß-LGH-Fe complex supplementation, IDC); three groups supplemented with different dosages of ß-LGH-Fe complex (0.5 mg Fe/kg BW, iron-deficient diet with low ß-LGH-Fe, IDLFe; 2.0 mg Fe/kg BW, iron-deficient diet with medium ß-LGH-Fe, IDMF; 4.0 mg Fe/kg BW, iron-deficient diet with high ß-LGH-Fe, IDHFe); and ferrous sulphate-supplemented group at a dosage of 2.0 mg Fe/kg BW. RESULTS: ß-LGH-Fe complex could significantly improve hematocrit and haemoglobin decrease, and normalise the serum iron level, total iron-binding capacity and transferrin saturation of anaemic rats in a dose-dependent manner. Serum ferritin content and hepatic nonheme iron level were also increased. In addition, the antioxidant enzyme activities of superoxidase dismutase, catalase and glutathione peroxidase in both plasma and liver homogenate were improved. The production of malondialdehyde and pro-inflammatory cytokines (TNF-α and IL-6) decreased. CONCLUSIONS: It suggests that ß-LGH-Fe complex can ameliorate iron deficiency anaemia, which might make it a potential ingredient with anti-anaemia activity.