Abstract
Bovine mastitis, an infection of the cow’s mammary gland, is frequently caused by Streptococcus uberis and causes major economic losses in the dairy industry. The intramammary administration of antibiotics currently remains the predominant preventive and therapeutic measure. These antimicrobial compounds, of which some are considered critical in human health care, are frequently applied as dry therapy resulting in their consistent overuse. Therefore, the use of antibiotics in the dairy sector is being questioned. We here identified two endolysins, i.e., PlySs2 and PlySs9, respectively derived from Streptococcus suis serotype-2 and -9 prophages, with lytic activity against S. uberis in an in vitro setting. Both endolysins gave clear lysis zones in spot-on-plate assays and caused a reduction of the optical density in a turbidity reduction assay. In depth characterization identified PlySs9 as the more potent endolysin over PlySs2 with a lower MIC value and about one additional log of killing. PlySs2 and PlySs9 were challenged to a panel of subclinical and clinical S. uberis milk isolates and were both able to lyse all strains tested. Molecular dissection of these endolysins in catalytic and cell wall binding subdomains resulted in major loss of killing and binding activity, respectively. Taken together, we here propose PlySs2 and PlySs9 as candidate compounds to the current antimicrobial arsenal known against bovine mastitis-causing S. uberis as future add-on or replacement strategy to the currently used intramammary antibiotics.
Highlights
Bovine mastitis, an infection of the cow’s udder, is the most important economic disease affecting dairy cattle [1,2]
We evaluated the in vitro lytic activity of PlySs2 and PlySs9, as well as their individual subdomains, as potential therapeutics in the future treatment of bovine mastitis caused by S. uberis
PlySs2 is 26.9 kDa in size and has an isoelectric point of 9.06. It consists of an N-terminal histidine-dependent amino hydrolase/peptidase (CHAP) catalytic domain and a C-terminal SH3_5 cell-wall binding domain (CBD)
Summary
An infection of the cow’s udder, is the most important economic disease affecting dairy cattle [1,2]. Antibiotics are still the main preventive and therapeutic tool for bovine mastitis, resulting in overuse mainly due to their application as dry therapy [10,11]. Several of these formulations contain quinolones, macrolides and cephalosporines of the third and fourth generation, which are considered critical in human health care by the World Health Organization [12]. With the consumer’s demand moving towards more sustainable dairy products, the role of antibiotics as a preventive and therapeutic measure in this sector is increasingly questioned
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
