Bovine mammary epithelial cell invasion by Streptococcus uberis

Area of Science:

• Veterinary Microbiology
• Bovine Pathology

Background:

• Streptococcus uberis is a primary bacterial pathogen responsible for bovine mastitis.
• The precise mechanisms underlying S. uberis pathogenesis, particularly epithelial cell invasion, remain incompletely understood.

Purpose of the Study:

• To investigate the in vitro invasiveness of Streptococcus uberis into bovine mammary epithelial cells.
• To explore the cellular and genetic factors influencing S. uberis epithelial cell invasion.

Main Methods:

• In vitro invasion assays using two S. uberis strains isolated from bovine mammary secretions.
• Assessment of cytoskeletal involvement (microfilaments and microtubules) during invasion.
• Genetic and phenotypic characterization of the S. uberis strains.

Main Results:

• Both S. uberis strains demonstrated invasiveness into bovine mammary epithelial cells, with varying levels observed between strains.
• Epithelial cell invasion was dependent on microfilaments but not microtubular cytoskeletal elements.
• No significant epithelial cell morphological changes or injury were detected post-infection up to 24 hours.
• The evaluated S. uberis strains were genetically distinct and exhibited phenotypic differences in potential virulence factor expression.

Conclusions:

• Streptococcus uberis possesses the ability to invade bovine mammary epithelial cells in vitro.
• Strain-specific differences in invasiveness suggest a role for distinct genetic and phenotypic factors.
• Epithelial cell invasion represents a potential key mechanism in the pathogenesis of Streptococcus uberis-induced bovine mastitis.