Comparative effect of selected adjuvants on the response in the bovine mammary gland to staphylococcal and streptococcal antigens

Study of the humoral immunological response after vaccination with a Staphylococcus aureus biofilm-embedded bacterin in dairy cows: possible role of the exopolysaccharide specific antibody production in the protection from Staphylococcus aureus induced mastitis

The objective of the present study was to analyze an extracellular component from Staphylococcus aureus (S. aureus), which we refer to as slime associated antigenic complex (SAAC), and to investigate the role of SAAC-specific antibody production in protection from S. aureus bovine mastitis. Twelve primiparous gestating cows were randomly assigned to one of the three groups: Group 1 was vaccinated with a S. aureus bacterin with very limited SAAC content; Group 2 received a S. aureus bacterin with high SAAC content and Group 3 served as unvaccinated controls. Animals were vaccinated at 45 days before the expected parturition date and revaccinated 35 days later. All groups were challenged by intramammary infusion with a virulent heterologous strain of S. aureus 23 days after calving. Antibody response against SAAC in serum and in milk, general clinical signs, mastitis score, somatic cell count (SCC) and count of S. aureus in milk were evaluated before and after challenge. Immunization with a high SAAC content in the S. aureus bacterin (Group 2) significantly enhanced antibody titers against SAAC (in serum and milk) and reduced the S. aureus concentration in milk during the post-challenge period compared to Group 1 and Group 3. Moreover, a significant negative correlation was observed between SAAC antibody production on the day of the challenge and the S. aureus count in milk by 1 day after challenge. However, there was no evidence of a difference between vaccinated and control groups with regard to clinical signs of mastitis following the challenge. Nevertheless, the SAAC antibody concentration on the day of the challenge negatively correlated with the mastitis score in quarters infected with S. aureus at 2 days post-challenge. These results indicate that the vaccines did not prevent S. aureus intramammary infection (IMI) after the experimental challenge, but immunization with a S. aureus bacterin with high SAAC content was able to reduce S. aureus multiplication in the mammary gland after challenge and suggests that the SAAC-specific antibody response could be involved in the protection against S. aureus intramammary infection. Although further studies should be performed to confirm the efficacy (under experimental conditions and in field trials), we propose bacterins from strong biofilm-producing bacteria and with high SAAC content, rather than with limited SAAC content, as a cost-efficient vaccine design against S. aureus bovine mastitis.

Protection from Staphylococcus aureus mastitis associated with poly-N-acetyl beta-1,6 glucosamine specific antibody production using biofilm-embedded bacteria

Staphylococcus aureus vaccines based on bacterins surrounded by slime, surface polysaccharides coupled to protein carriers and polysaccharides embedded in liposomes administered together with non-biofilm bacterins confer protection against mastitis. However, it remains unknown whether protective antibodies are directed to slime-associated known exopolysaccharides and could be produced in the absence of bacterin immunizations. Here, a sheep mastitis vaccination study was carried out using bacterins, crude bacterial extracts or a purified exopolysaccharide from biofilm bacteria delivered in different vehicles. This polysaccharide reacted specifically with antibodies to poly-N-acetyl-beta-1,6-glucosamine (PNAG) and not with antibodies to other capsular antigens or bacterial components. Following intra-mammary challenge with biofilm-producing bacteria, antibody production against the polysaccharide, milk bacterial counts and mastitis lesions were determined. Bacterins from strong biofilm-producing bacteria triggered the highest production of antibodies to PNAG and conferred the highest protection against infection and mastitis, compared with weak biofilm-producing bacteria and non-cellular inocula. Thus, bacterins from strong biofilm bacteria, rather than purified polysaccharide, are proposed as a cost-efficient vaccination against S. aureus ruminant mastitis.

Antibody responses in sheep vaccinated against Staphylococcus aureus mastitis: a comparison of two experimental vaccines containing different adjuvants

A double-blind, placebo-controlled study was conducted to compare two vaccines using different adjuvants with regard to their ability to stimulate antibody production against the alpha- and beta-toxins and the exopolysaccharide of Staphylococcus aureus. The vaccines contained identical antigens, consisting of inactivated whole bacteria of two strains of S. aureus in addition to alpha- and beta-toxoid. One vaccine contained mineral oil, while the other used a water-soluble acrylic acid polymer resin (Carbopol) as adjuvant. Saline served as the placebo. One hundred and forty ewes were vaccinated twice before lambing, by subcutaneous injection with vaccine or placebo in the region of the supramammary lymph node, and were observed and sampled over a period of 6 months. The vaccine containing mineral oil as adjuvant induced significantly greater immune responses to the alpha- and beta-toxins than did the vaccine containing Carbopol. The latter vaccine induced higher levels of antibodies to exopolysaccharide. The degree of local adverse reactions did not differ between the two groups. The results indicate differences between the oil-adjuvanted and Carbopol-adjuvanted vaccines with regard to their ability to stimulate antibody production against S. aureus protein antigens in sheep.

Efficacy of inactivated whole-cell vaccines against streptococcosis in pigeons

Two experimental vaccines were developed and evaluated for their efficacy against Streptococcus gallolyticus septicaemia in pigeons. Both vaccines contained whole-cell formaldehyde-inactivated S. gallolyticus serotype 1 bacteria and a mineral oil adjuvant. The supernatant of a S. gallolyticus broth culture was also added to one of the vaccines. Four groups of 10 pigeons were inoculated either once, or twice, with a 4-week interval, with one of the vaccines. Four weeks after the last vaccination, pigeons were challenged by intravenous inoculation with S. gallolyticus serotype 1. Morbidity after infection was not significantly different between groups of pigeons vaccinated with the two vaccines. In groups of pigeons vaccinated once, morbidity after infection ranged from 50 to 70%; in pigeons vaccinated twice, morbidity was 10 to 30%. In a non-vaccinated inoculated control group, the morbidity was 80%. It was concluded that double vaccination can result in some clinical protection against streptococcosis in pigeons.

Immunogenic properties of Staphylococcus aureus and Streptococcus agalactiae administered separately and in combination to lactating cows

Composite bacterins of Staphylococcus aureus and Streptococcus agalactiae, or either bacterin alone, were administered systemically to groups of lactating cows. The response to each bacterin was unaffected by the simultaneous administration of the antigens when assessed by comparing the antibody levels in milk by enzyme-linked immunosorbent assay. There was no evidence of cross reactivity of the antigens studied, nor immunopotentiation by either bacteria.