Genomic analysis and immune response in a murine mastitis model of vB_EcoM-UFV13, a potential biocontrol agent for use in dairy cows

Vinícius Da Silva Duarte,Camila Geovana Ferro,Roberto Sousa Dias,Andrew M Kropinski,Stefano Campanaro,Carolina Siqueira,Gabriele Rocha Santana,Franciele Martins,André Da Silva Xavier,Cynthia Canêdo Da Silva,Pedro M P Vidigal,Isabela Da Silva Paes,Josicelli Souza Crispim,Sérgio Oliveira De Paula,Marcella Silva Vieira,Laura Treu

doi:10.1038/s41598-018-24896-w

Abstract

Bovine mastitis remains the main cause of economic losses for dairy farmers. Mammary pathogenic Escherichia coli (MPEC) is related to an acute mastitis and its treatment is still based on the use of antibiotics. In the era of antimicrobial resistance (AMR), bacterial viruses (bacteriophages) present as an efficient treatment or prophylactic option. However, this makes it essential that its genetic structure, stability and interaction with the host immune system be thoroughly characterized. The present study analyzed a novel, broad host-range anti-mastitis agent, the T4virus vB_EcoM-UFV13 in genomic terms, and its activity against a MPEC strain in an experimental E. coli-induced mastitis mouse model. 4,975 Single Nucleotide Polymorphisms (SNPs) were assigned between vB_EcoM-UFV13 and E. coli phage T4 genomes with high impact on coding sequences (CDS) (37.60%) for virion proteins. Phylogenetic trees and genome analysis supported a recent infection mix between vB_EcoM-UFV13 and Shigella phage Shfl2. After a viral stability evaluation (e.g pH and temperature), intramammary administration (MOI 10) resulted in a 10-fold reduction in bacterial load. Furthermore, pro-inflammatory cytokines, such as IL-6 and TNF-α, were observed after viral treatment. This work brings the whole characterization and immune response to vB_EcoM-UFV13, a biocontrol candidate for bovine mastitis.

Highlights

IntroductionMammary pathogenic Escherichia coli (MPEC) is related to an acute mastitis and its treatment is still based on the use of antibiotics
Bovine mastitis remains the main cause of economic losses for dairy farmers
Bacteriophage UFV13 was isolated from samples obtained in the sewage system of Viçosa, Minas Gerais, Brazil, a well-known source of novel viruses[57]

Summary

Introduction

Mammary pathogenic Escherichia coli (MPEC) is related to an acute mastitis and its treatment is still based on the use of antibiotics. In the era of antimicrobial resistance (AMR), bacterial viruses (bacteriophages) present as an efficient treatment or prophylactic option This makes it essential that its genetic structure, stability and interaction with the host immune system be thoroughly characterized. In terms of the lactation period and regarding clinical mastitis, Escherichia coli, Streptococcus uberis, Streptococcus dysgalactiae and Staphylococcus aureus are the main etiological agents involved that have been routinely isolated[5]. Among these pathogens, mammary pathogenic Escherichia coli (MPEC) is www.nature.com/scientificreports/. Using E. coli strains obtained from different types of mastitis (e.g per-acute and persistent) and the non-pathogenic strain K71, Blum et al (2017) performed a mammary immune response comparison in experimentally infected cows and noticed differences regarding TNF-α, IL-6 and IL-17 secretion levels for each MPEC

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