Kinetics of systemic immune cells populations after an intramammary experimental infection of dairy cows with two Staphylococcus aureus strains with distinct adaptation genotypes

ENGLER, C; PIROLA S; BECCARIA C; SILVESTRINI, P; SIMONUTTI V; BARAVALLE C; CALVINHO L.F; DALLARD BE; RENNA M.S

Conferencia; Reunión Conjunta SAIC, SAI, SAFIS; 2022

The aim of this study was to evaluate whether systemic immune cells populations undergo changes after an experimental intramammary infection with two S. aureus strains with different adaptation genotypes (low and high) to the bovine mammary gland. Three groups of clinically healthy cows, 4 cows/group, were inoculated by the intramammary route in two mammary quarters with S. aureus 806 strain (non persistent-NP), S. aureus 5011 strain (persistent-P) and pyrogen-free saline solution (control group). Peripheral blood samples were collected at 0, 0.5, 1, 2, 3, 4, 7, 14 and 21 days post-inoculation (pi) from all groups to evaluate the frequency of monocytes, LB, LTCD4 and LTCD8 by flow cytometry. A Generalized Linear Model was used to analyze the results. No effect of infection was observed between groups in the percentages of monocytes over time (p=0.842). When only day 2 pi was analyzed, a decrease in the percentages of monocytes was observed in animals inoculated with NP strain (p=0.033). A significant effect of infection was observed between groups in the percentages of LB over time (p=0.025). On day 3 pi, a decrease in the percentages of LB was observed in animals inoculated with P strain (p