Phagovet

Broad-spectrum high-efficiency phage vB_SalP_LDW16 – Poultry

Antibiotics are often the drug of choice for treating salmonellosis, but their misuse can lead to the emergence of drug-resistant strains of Salmonella. This study, however, cleverly solved this conundrum by separating and purifying no fewer than 16 Salmonella bacteriophages from sewage and poultry feces. Fortunately, this led to something even better – vB_SalP_LDW16 was selected from these phages and proved to be a practically viable option for the safe treatment of Salmonella. After demonstrating the efficacy of vB_SalP_LDW16 in double-layer plate and transmission electron microscopy tests, its clinical efficacy was successfully demonstrated using Salmonella Enteritidis in an SPF chicken model.

The phage vB_SalP_LDW16 may play a crucial role for antibiotic treatment in livestock. Its highly lytic properties combined with its broad host range make it an ideal candidate for the prevention and treatment of salmonellosis in chickens – it also offers an ecological and sustainable alternative to conventional antibiotics.

The authors Shengliang Cao, Wenwen Yang, Xihui Zhu, Cheng Liu, Jianbiao Lu, Zhenshu Si, Lanying Pei, Leilei Zhang, Wensi Hu, Yanlan Li, Zhiwei Wang, Zheyu Pang, Xijuan Xue, and Yubao Li published their article ‘Isolation and identification of the broad-spectrum high-efficiency phage vB_SalP_LDW16 and its therapeutic application in chickens‘ on 3 November 2022.

Key topics include:

  • Salmonella infections in livestock and poultry cause salmonellosis, which is mainly treated with antibiotics.
  • However, misuse of antibiotics often leads to the emergence of multidrug-resistant Salmonella strains.
  • Currently, Salmonella phages are safe and effective against Salmonella and serve as the best drug of choice.
  • In this study, 16 Salmonella bacteriophages were separated and purified from wastewater and fecal samples from a chicken farm.
  • A phage named vB_SalP_LDW16 was selected based on the results of its host range test. The phage was characterized using the double-layer plate method and transmission electron microscopy.
  • In addition, the clinical therapeutic effect of the phage vB_SalP_LDW16 was verified by its application to pathogenic Salmonella Enteritidis in an SPF chicken model.
  • The results showed that vB_SalP_LDW16 is a highly lytic phage with a broad host range that can be used to prevent and treat salmonellosis in chickens as an alternative or complement to antibiotic treatment in livestock …
Isolation and identification of the broad-spectrum high-efficiency phage chickens Salmonella

Abstract

Background

Salmonella infection in livestock and poultry causes salmonellosis, and is mainly treated using antibiotics. However, the misuse use of antibiotics often triggers the emergence of multi-drug-resistant Salmonella strains. Currently, Salmonella phages is safe and effective against Salmonella, serving as the best drug of choice. This study involved 16 Salmonella bacteriophages separated and purified from the sewage and the feces of the broiler farm. A phage, vB_SalP_LDW16, was selected based on the phage host range test. The phage vB_SalP_LDW16 was characterized by the double-layer plate method and transmission electron microscopy. Furthermore, the clinical therapeutic effect of phage vB_SalP_LDW16 was verified by using the pathogenic Salmonella Enteritidis in the SPF chicken model.

Results

The phage vB_SalP_LDW16 with a wide host range was identified to the family Siphoviridae and the order Caudoviridae, possess a double-stranded DNA and can lyse 88% (22/25) of Salmonella strains stored in the laboratory. Analysis of the biological characteristics, in addition, revealed the optimal multiplicity of infection (MOI) of vB_SalP_LDW16 to be 0.01 and the phage titer to be up to 3 × 1014 PFU/mL. Meanwhile, the phage vB_SalP_LDW16 was found to have some temperature tolerance, while the titer decreases rapidly above 60 ℃, and a wide pH (i.e., 5-12) range as well as relative stability in pH tolerance. The latent period of phage was 10 min, the burst period was 60 min, and the burst size was 110 PFU/cell. Furthermore, gastric juice was also found to highly influence the activity of the phage. The clinical treatment experiments showed that phage vB_SalP_LDW16 was able to significantly reduce the bacterial load in the blood through phage treatment, thereby improving the pathological changes in the intestinal, liver, and heart damage, and promoting the growth and development of the chicken.

Conclusions

The phage vB_SalP_LDW16 is a highly lytic phage with a wide host range, which can be potentially used for preventing and treating chicken salmonellosis, as an alternative or complementary antibiotic treatment in livestock farming.

Keywords: Biological characteristics; Phage therapy; Phages vB_SalP_LDW16; Recovery rate; Salmonella.

© 2022. The Authors.