Immune modification of the pathogenesis of Streptococcus uberis mastitis in the dairy cow

Abstract

Two groups of 4 cows were vaccinated subcutaneously with live Streptococcus uberis strain 0140J or a surface extract derived from the same strain, at 14 days prior to the cessation of lactation (drying off) and at calving. Both groups also received an intramammary administration of the surface extract 7 days after drying off. A third group of unvaccinated animals acted as controls. Following intramammary challenge of two quarters per cow with the vaccine strain, all quarters on control cows and those vaccinated only with surface extract developed clinical mastitis. However, only 12.5% of challenged quarters on cows which were vaccinated with live bacteria developed clinical mastitis. In addition, the numbers of bacteria in the milk following challenge were 10(5) times higher from the control and extract vaccinated cows than those which received live vaccine. Serum levels of S. uberis specific IgG2 were elevated in the animals vaccinated with the live organism when compared to that of either extract-vaccinates or controls, whilst S. uberis specific levels of IgG1 and IgM were similar in all groups throughout the experiment. Specific antibody levels in milk were unaffected by vaccination. Despite increased levels of IgG2, no increase in opsonic activity was detected in any serum or milk samples. Peripheral blood lymphocytes from animals vaccinated with live organisms showed a considerable increase in proliferative response to S. uberis antigen in vitro when compared with lymphocytes from control and extract-vaccinated animals. These results suggest that neutrophils and specific opsonising antibody may not form the major defence against infection with S. uberis.

Identification and Disruption of Two Discrete Loci Encoding Hyaluronic Acid Capsule Biosynthesis Genes hasA , hasB , and hasC in Streptococcus uberis

“…Correspondingly, the three strains found to lack hasABhomologous DNA exhibited an acapsular phenotype. The resistance of S. uberis strains to phagocytosis by bovine neutrophils can be induced in vitro when the organism is grown in the presence of casein-derived peptides, an observation that is consistent with those made in vivo following experimental infection of the lactating mammary gland (11). Capsular strains of S. uberis appear to be resistant to phagocytosis, whereas acapsular strains are more readily phagocytosed and killed by bovine neutrophils (17).…”

Effect of Recombinant Bovine Somatotropin on Milk Production and Composition of Cows with Streptococcus uberis Mastitis

“…A high neutrophil influx induces severe damage during S. uberis mastitis, and the rate of influx of polymorphonuclear leukocytes during E. coli mastitis is determinant for the outcome and severity of E. coli mastitis (17). Neutrophils are ineffective at controlling infection caused by S. uberis (16); however, macrophages are important (46). Treatment with bST had no effect on the recovery of SCC in both the E. coli and S. uberis mastitis studies.…”

“…Indeed, acute E. coli mastitis after calving is accompanied by severe systemic symptoms, especially in the so-called severe responders (47), with, in some cases, even shock and death. These severe systemic signs are not observed during S. uberis mastitis, which is characterized by local mastitis symptoms and very few systemic symptoms (16). In addition, neutrophils are of major importance in the pathogenesis of E. coli mastitis, but contribute little to the pathogenesis of S. uberis mastitis (16,17).…”

“…These severe systemic signs are not observed during S. uberis mastitis, which is characterized by local mastitis symptoms and very few systemic symptoms (16). In addition, neutrophils are of major importance in the pathogenesis of E. coli mastitis, but contribute little to the pathogenesis of S. uberis mastitis (16,17). Moreover, antibiotic treatment of acute coliform mastitis always comes too late, but is necessary to cure streptococcal mastitis.…”

MtuA, a Lipoprotein Receptor Antigen from Streptococcus uberis , Is Responsible for Acquisition of Manganese during Growth in Milk and Is Essential for Infection of the Lactating Bovine Mammary Gland

“…Within the lactating gland S. uberis is able to replicate to around 10 7 to 10 8 CFU/ml of milk, resist the bactericidal action of neutrophils, and induce an inflammatory response (12,13,17,32). During a clinical episode of disease it is not uncommon for neutrophils and bacteria to coexist within the secretion at a level of 10 7 CFU/ml of milk (12,13,17,32). In addition to being able to infect the lactating mammary gland, S. uberis is also able to infect the nonlactating or dry gland.…”