Effect of hyperimmunization with an Escherichia coli J5 bacterin in adult lactating dairy cows

Selective IgG binding to the LPS glycolipid core found in bovine colostrum, or milk, during Escherichia coli mastitis influences endotoxin function

The dynamic interplay between intramammary IgG, formation of antigen-IgG complexes and effector immune cell function is essential for immune homeostasis within the bovine mammary gland. We explore how changes in the recognition and binding of anti-LPS IgG to the glycolipid "functional" core in milk from healthy or clinically diagnosed Escherichia coli (E. coli) mastitis cows' controls endotoxin function. In colostrum, we found a varied anti-LPS IgG repertoire and novel soluble LPS/IgG complexes with direct IgG binding to the LPS glycolipid core. These soluble complexes, absent in milk from healthy lactating cows, were evident in cows diagnosed with E. coli mastitis and correlated with endotoxin-driven inflammation. E. coli mastitis milk displayed a proportional reduction in anti-LPS glycolipid core IgG compared to colostrum. Milk IgG extracts showed that only colostrum IgG attenuated LPS induced endotoxin activity. Furthermore, LPS-stimulated reactive oxygen species (ROS) in milk granulocytes was only suppressed by colostrum IgG, while IgG extracts of neither colostrum nor E. coli mastitis milk influenced N-formylmethionine-leucyl-phenylalanine (fMLP)-stimulated ROS in LPS primed granulocytes. Our findings support bovine intramammary IgG diversity in health and in response to E. coli infection generate milk anti-LPS IgG repertoires that coordinate appropriate LPS innate-adaptive immune responses essential for animal health.

Effects of a mastitis J5 bacterin vaccination on the productive performance of dairy cows: An observational study using propensity score matching techniques

Inferring causal effects between variables when utilizing observational data is challenging due to confounding factors not controlled through a randomized experiment. Propensity score matching can decrease confounding in observational studies and offers insights about potential causal effects of prophylactic management interventions such as vaccinations. The objective of this study was to determine potential causality and impact of vaccination with an Escherichia coli J5 bacterin on the productive performance of dairy cows applying propensity score matching techniques to farm-recorded (e.g., observational) data. Traits of interest included 305-d milk yield (MY305), 305-d fat yield (FY305), 305-d protein yield (PY305), and somatic cell score (SCS). Records from 6,418 lactations generated by 5,121 animals were available for the analysis. Vaccination status of each animal was obtained from producer-recorded information. Confounding variables considered were herd-year-season groups (56 levels), parity (5 levels: 1, 2, 3, 4, and ≥5), and genetic quartile groups (4 levels: top 25% through bottom 25%) derived from genetic predictions for MY305, FY305, PY305, and SCS, as well as for the genetic susceptibility to mastitis. A logistic regression model was applied to estimate the propensity score (PS) for each cow. Subsequently, PS values were used to form pairs of animals (1 vaccinated with 1 unvaccinated control), depending on their PS similarities (difference in PS values of cows within a match required to be <20% of 1 standard deviation of the logit of PS). After the matching process, 2,091 pairs of animals (4,182 records) remained available to infer the causal effects of vaccinating dairy cows with the E. coli J5 bacterin. Causal effects estimation was performed using 2 approaches: simple matching and a bias-corrected matching. According to the PS methodology, causal effects of vaccinating dairy cows with a J5 bacterin on their productive performance were identified for MY305. The simple matched estimator suggested that vaccinated cows produced 163.89 kg more milk over an entire lactation when compared with nonvaccinated counterparts, whereas the bias-corrected estimator suggested that such increment in milk production was of 150.48 kg. Conversely, no causal effects of immunizing dairy cows with a J5 bacterin were identified for FY305, PY305, or SCS. In conclusion, the utilization of PS matching techniques applied to farm-recorded data was feasible and allowed us to identify that vaccination with an E. coli J5 bacterin relates to an overall milk production increment without compromising milk quality.

Escherichia coli Mastitis in Dairy Cattle: Etiology, Diagnosis, and Treatment Challenges

Bovine mastitis is an inflammation of the udder tissue parenchyma that causes pathological changes in the glandular tissue and abnormalities in milk leading to significant economic losses to the dairy industry across the world. Mammary pathogenic Escherichia (E.) coli (MPEC) is one of the main etiologic agents of acute clinical mastitis in dairy cattle. MPEC strains have virulence attributes to resist the host innate defenses and thrive in the mammary gland environment. The association between specific virulence factors of MPEC with the severity of mastitis in cattle is not fully understood. Furthermore, the indiscriminate use of antibiotics to treat mastitis has resulted in antimicrobial resistance to all major antibiotic classes in MPEC. A thorough understanding of MPEC’s pathogenesis and antimicrobial susceptibility pattern is required to develop better interventions to reduce mastitis incidence and prevalence in cattle and the environment. This review compiles important information on mastitis caused by MPEC (e.g., types of mastitis, host immune response, diagnosis, treatment, and control of the disease) as well as the current knowledge on MPEC virulence factors, antimicrobial resistance, and the dilemma of MPEC as a new pathotype. The information provided in this review is critical to identifying gaps in knowledge that will guide future studies to better design diagnostic, prevent, and develop therapeutic interventions for this significant dairy disease.

Invited review: A critical appraisal of mastitis vaccines for dairy cows

Infections of the mammary gland remain a frequent disease of dairy ruminants that negatively affect animal welfare, milk quality, farmer serenity, and farming profitability and cause an increase in use of antimicrobials. There is a need for efficacious vaccines to alleviate the burden of mastitis in dairy farming, but this need has not been satisfactorily fulfilled despite decades of research. A careful appraisal of past and current research on mastitis vaccines reveals the peculiarities but also the commonalities among mammary gland infections associated with the major mastitis pathogens Escherichia coli, Staphylococcus aureus, Streptococcus uberis, Streptococcus agalactiae, or Streptococcus dysgalactiae. A major pitfall is that the immune mechanisms of effective protection have not been fully identified. Until now, vaccine development has been directed toward the generation of antibodies. In this review, we drew up an inventory of the main approaches used to design vaccines that aim at the major pathogens for the mammary gland, and we critically appraised the current and tentative vaccines. In particular, we sought to relate efficacy to vaccine-induced defense mechanisms to shed light on some possible reasons for current vaccine shortcomings. Based on the lessons learned from past attempts and the recent results of current research, the design of effective vaccines may take a new turn in the years to come.

Shielding Effect of Escherichia coli O-Antigen Polysaccharide on J5-Induced Cross-Reactive Antibodies

Despite intensive research, mastitis remains an important disease in dairy cattle with a significant impact on animal welfare, use of antibiotics, and, in the end, the economy of dairy farms. Although vaccines available so far have shown limited efficacy against coliform mastitis, vaccination is considered one of the measures that could limit the consequences of mastitis.

Escherichia coli is the leading cause of severe mastitis in dairy farms. As E. coli mastitis is refractory to the hygienic control measures adapted to contagious mastitis, efficient vaccines are in demand. Existing mastitis vaccines, based on the use of killed rough E. coli J5 as the antigen, aim at inducing phagocytosis by neutrophils. We assessed the binding of J5-induced antibodies to isogenic rough and smooth strains along with a panel of mastitis-associated E. coli. Analysis by enzyme-linked immunosorbent assay revealed that antibodies to OmpA or killed J5 bind readily to rough E. coli but poorly to smooth strains. Flow cytometry analysis indicated that immunization with J5 induced antibodies that cross-reacted with rough E. coli strains but with only a small subpopulation of smooth strains. We identified type 1 fimbriae as the target of most antibodies cross-reacting with the smooth strains. These results suggest that the O-polysaccharide of lipopolysaccharide shields the outer membrane antigens and that only fiber antigens protruding at the bacterial surface can elicit antibodies reacting with mastitis-associated E. coli. We evaluated J5-induced antibodies in an opsonophagocytic killing assay with bovine neutrophils. J5 immune serum was not more efficient than preimmune serum, showing that immunization did not improve on the already high efficiency of naturally acquired antibodies to E. coli. In conclusion, it is unlikely that the efficiency of J5 vaccines is related to the induction of opsonic antibodies. Consequently, other research directions, such as cell-mediated immunity, should be explored to improve E. coli mastitis vaccines.

IMPORTANCE Despite intensive research, mastitis remains an important disease in dairy cattle with a significant impact on animal welfare, use of antibiotics, and, in the end, the economy of dairy farms. Although vaccines available so far have shown limited efficacy against coliform mastitis, vaccination is considered one of the measures that could limit the consequences of mastitis. One reason for the lack of efficiency of current vaccines likely stems from the current evaluation of vaccines that relies mostly on measuring antibody production against vaccine antigens. This report clearly shows that vaccine-induced antibodies fail to bind to most mastitis-associated E. coli strains because of the presence of an O-antigen and, thus, do not allow for improved phagocytosis of pathogens. As a consequence, this report calls for revised criteria for the evaluation of vaccines and suggests that cell-mediated immunity should be targeted by new vaccinal strategies. More generally, these results could be extended to other vaccine development strategies targeting coliform bacteria.

The effect of J5 bacterins on clinical, behavioral, and antibody response following an Escherichia coli intramammary challenge in dairy cows at peak lactation

Vaccination against coliform mastitis has become part of mastitis control programs in the past 3 decades, as a means of reducing the severity of clinical mastitis. Our study objective was to evaluate the effect of 2 commercially available vaccines on clinical, behavioral, and antibody response following Escherichia coli intramammary challenge in cows near peak lactation. Cows (n = 12 per group) were vaccinated with vaccine 1 (V1) or vaccine 2 (V2) at dry-off, 21 d pre-calving, and 14 d post-calving. Twelve cows served as unvaccinated controls (CTL). Cows were challenged with E. coli in a rear quarter at approximately 100 d in milk. Milk samples were collected pre- and post-challenge to enumerate E. coli and determine somatic cell count. Serum was collected before each vaccination and at d 0, 1, 2, 3, 6, 30, and 60 relative to challenge, to study antibody response. Milk IgA and tumor necrosis factor-α concentrations were determined in whey. Vaginal temperature, cow activity, and milk yield and components were monitored post-challenge. Bacterial count, somatic cell score, milk yield and component decline, vaginal temperature, activity measures, and antibody and cytokine response were analyzed for treatment differences. The effects of parity, breed, and a repeated measure of time were also tested. Seven cows had to be removed from the study post-challenge for antibiotic treatment (CTL and V1, n = 3 each; V2, n = 1), 2 of which were euthanized (both CTL). Vaccinated cows exhibited fever (vaginal temperature ≥39.4°C) 3 h earlier than CTL cows, but we found no differences between treatments for bacterial count, somatic cell score, or milk yield reduction. Vaccinated cows spent more time lying per rest bout 2 d post-challenge, but total daily lying time was not different from CTL cows during the 7 d post-challenge. The vaccines differed in antibody response: V1 cows had greater serum IgG₁ and IgG₂ post-challenge. A parity effect was also evident: primiparous cows had lower bacterial counts, somatic cell score and a smaller milk yield decline than multiparous cows, but also had lower antibody production. Immunization with either J5 bacterin did not reduce clinical signs of mastitis in cows challenged at 100 d in milk, demonstrating that the effects of J5 vaccination had diminished at peak lactation.

Vaccination strategies for mastitis

Presently, the most successful use of vaccination strategies as part of a dairy herd mastitis control program involves GNCABs, of which the J-5 bacterins are best understood. Immunization protocols employing this technology should be adapted to individual herd needs. Ironically, the success of these bacterins may rely, in part, on the systemic pathogensis of severe coliform mastitis. Because immune function is impaired in the mammary gland of a lactating dairy cow, and the difficulty in maintaining effective concentrations of antibodies in milk following vaccination, vaccines developed against pathogens that cause more chronic IMI, while promising, have significant obstacles to overcome.

Mastitis: comparative etiology and epidemiology

Mastitis is broadly defined as the inflammation of the mammary gland; however, the concept of mastitis is customized to address its social and clinical impact in the case of humans and the health, welfare, and economic consequences for other mammals. There are many microbial, host, and environmental factors that influence the development of mastitis. Some are common to all mammals as well as inherent to each species. Together these factors influence the most prevalent etiological agents for each species and might determine the possibility of interspecies transmission with its consequences to public health. The present review will summarize and compare reports on mastitis etiology and its epidemiology in humans and food animal species.

Bovine Leukemia Virus Infection in Dairy Cattle: Effect on Serological Response to Immunization against J5 Escherichia coli Bacterin

Thirteen bovine leukemia virus- (BLV-) negative and 22 BLV-positive Holstein cows were immunized with J5 Escherichia coli bacterin at dry off, three weeks before calving, during the second week after calving, and three weeks after the third immunization. Serum was collected before the initial immunization, immediately before the third and fourth immunizations, and 21 days after the fourth immunization. Anti-J5 E. coli IgM, IgG1, and IgG2 titers were determined by ELISA. Anti-J5 E. coli IgM titers did not differ significantly (P = .98) between groups. Increases in anti-J5 E. coli IgG1 titers were higher in the BLV-negative cows (P = .057). Geometric mean anti-J5 E. coli IgG2 titers increased fourfold in the BLV-negative cows, which was significantly higher (P = .007) than the twofold increase in the BLV-positive cows. Cattle infected with BLV may have impaired serologic responses following immunization with J5 bacterin, and response may differ according to antibody isotype.

Perspectives on immunoglobulins in colostrum and milk

Immunoglobulins form an important component of the immunological activity found in milk and colostrum. They are central to the immunological link that occurs when the mother transfers passive immunity to the offspring. The mechanism of transfer varies among mammalian species. Cattle provide a readily available immune rich colostrum and milk in large quantities, making those secretions important potential sources of immune products that may benefit humans. Immune milk is a term used to describe a range of products of the bovine mammary gland that have been tested against several human diseases. The use of colostrum or milk as a source of immunoglobulins, whether intended for the neonate of the species producing the secretion or for a different species, can be viewed in the context of the types of immunoglobulins in the secretion, the mechanisms by which the immunoglobulins are secreted, and the mechanisms by which the neonate or adult consuming the milk then gains immunological benefit. The stability of immunoglobulins as they undergo processing in the milk, or undergo digestion in the intestine, is an additional consideration for evaluating the value of milk immunoglobulins. This review summarizes the fundamental knowledge of immunoglobulins found in colostrum, milk, and immune milk.

Effect of changes in number of doses and anatomic location for administration of an Escherichia coli bacterin on serum IgG1 and IgG2 concentrations in dairy cows

OBJECTIVE

To determine effects of injection site on antibody response to J5 Escherichia coli bacterin.

ANIMALS

28 adult Holstein cows.

PROCEDURES

Cows were randomly assigned as control cattle (n = 4 cows), not administered J5 E coli bacterin; 3X (8), administered 3 doses of bacterin SC in the left side of the neck; 5XN (8), administered 5 doses of bacterin SC in the left side of the neck; or 5XSR (8), administered 5 doses of bacterin SC sequentially in the left side of the neck, right side of the neck, right side of the thorax, left side of the thorax, and left side of the neck. Blood samples were collected from the cows to determine anti-J5 E coli IgG1 and IgG2 concentrations.

RESULTS

Vaccinated cows had higher mean serum anti-J5 E coli IgG1 concentrations than did control cows. The 5XN and 5XSR cows had higher mean serum anti-J5 E coli IgG1 concentrations than did 3X cows. Additionally, 5XSR cows had higher mean serum anti-J5 E coli IgG1 concentrations than did 5XN cows. Vaccinated cows had higher mean serum anti-J5 E coli IgG2 concentrations than did control cows. The 5XN and 5XSR cows had higher mean serum anti-J5 E coli IgG2 concentrations than did 3X cows. The 5XSR cows had higher mean serum anti-J5 E coli IgG2 concentrations than did all other groups at 84 days after the fifth vaccination.

CONCLUSIONS AND CLINICAL RELEVANCE

Sequential doses of core-antigen bacterins administered at different anatomic locations may improve antibody response in dairy cattle.