Quantification of bovine IgG, IgM and IgA antibodies to Clostridium perfringens B-toxin by enzyme immunoassay I. Preparturient immunization for enhancement of passive transfer of immunity

Impact of prepartum administration of a vaccine against infectious calf diarrhea on nonspecific colostral immunoglobulin concentrations of dairy cows

Passive transfer of colostral immunoglobulins from the cow to the calf is essential for calf health. The objective of this study was to determine if prepartum administration of a vaccine stimulates increased concentrations of colostral immunoglobulins of dairy cows beyond what is explained by vaccine-specific immunoglobulins. A prospective cohort study was conducted on a spring-calving commercial dairy farm that had a policy of only vaccinating cows with even ear tag numbers with a calf diarrhea vaccine, while cows with odd ear tag numbers were left unvaccinated. Cows in the vaccinated group (even ear tag numbers, n=204) received a sensitizer and booster vaccination with a vaccine against bovine rotavirus (serotypes G6 and G10), bovine coronavirus and E. coli having the K99 pili adherence factor. A sensitizer was given because the study vaccine was different to the vaccine previously used. Cows in the control group (odd ear tag numbers, n=194) received a 2 mL subcutaneous sterile saline solution. Both groups received two treatments at a three-week interval, completing the treatments approximately two weeks prior to the planned start of calving. During the calving period, technicians separated calves from cows immediately after parturition and prior to suckling, and cows were completely milked out within six hours of parturition. Vaccine-specific, total, and nonvaccine-specific (total minus vaccine-specific) concentrations of immunoglobulin classes A, G1, G2a and M (IgA, IgG1, IgG2a and IgM respectively) were quantified by mass spectrometry for 20 colostrum samples from each treatment group. Predicted mean non-vaccine-specific colostral IgM concentrations were 8.76 (95% CI =7.18-10.67) and 5.78 (95% CI =4.74-7.05) mg/ml for vaccinated and control cows respectively (p =0.005). Predicted mean non-vaccine-specific colostral IgG1 concentrations were 106.08 (95% CI =92.07-120.08) and 95.30 (95% CI =81.30-109.31) mg/ml among vaccinated and control cows respectively, however these means were not significantly different (p=0.278). It is thus possible that the vaccine, in addition to specifically managing infectious calf diarrhea, may also have non-specific benefits by improving colostrum quality through increased non-vaccine-specific colostrum IgM concentrations. Further research is necessary to determine the mechanism for these preliminary findings, whether the effect may occur in other immunoglobulin classes, and what impacts it may have on calf health outcomes.

Development and prevalidation of two different ELISA systems for the potency testing of Clostridium perfringens beta and epsilon-toxoid containing veterinary vaccines

The potency testing of Clostridium perfringens mono- and multicomponent veterinary vaccines is currently performed with the mouse neutralisation test (MNT) to estimate levels of C. perfringens beta- and epsilon-antitoxin levels in the sera of rabbits immunised with the vaccine. Two in vitro methods based on monoclonal antibodies (mAb) have been developed for the determination of specific antibodies against C. perfringens beta-toxin (capture ELISA) and epsilon-toxin (competitive ELISA) in these sera. Both test systems show high specificity and good reproducibility. These ELISA procedures were used in addition to the routine batch potency test in mice (MNT) to determine beta- and epsilon-antitoxin levels in 523 samples of rabbit serum. There was good agreement between the rank order of sera determined in vivo and the rank order determined in vitro. Linear regression analysis gave correlation coefficients of 0.88 for the capture ELISA and 0.41 for the competitive ELISA, with a significance level of P < 0.01 in both cases. Furthermore, a prevalidation study was carried out in four laboratories to evaluate the transferability of the ELISA procedures and the interlaboratory reproducibility of the results. Three coded serum samples were tested several times. The results indicated that both ELISA systems are suitable candidates to replace the MNT used for the potency testing of beta- and epsilon-toxoid in mono- and multicomponent veterinary vaccines. However, these assays still need to be validated in an international collaborative study.

Vaccination of grasscutters with a multicomponent clostridial vaccine

Grasscutter serum antibodies against Clostridium perfringens beta-toxin were titrated in an enzyme immunoassay. The procedure that is currently used for vaccinating domesticated grasscutters is discussed.

Humoral immunity in the ewe. 3. The influence of adjuvants and immunisation regimes on immune reactivity in the breeding ewe and her progeny

Breeding ewes were immunised with clostridial vaccine using different inoculation schedules. Results, showing differences in the class of antibody produced, were heavily dependent on the vaccination regime used. Immunoglobulin M (IgM) levels were significantly lower in ewes given double doses of vaccine compared to ewes given a single inoculation or no treatment at all (P less than 0.01). Neonatal lambs showed significant de novo IgM production with interference in this antibody production in the lambs of ewes vaccinated with the clostridial vaccine (P less than 0.05). Immunoglobulin G1 (IgG1) levels were significantly increased in all lambs which had mothers vaccinated with the clostridial vaccine prior to or during pregnancy (P less than 0.025). The greatest quantity of IgG1 was transferred to lambs when their mothers were given a double injection with primary inoculation prior to conception and booster prepartum (P less than 0.025). No antigen specific immunoglobulin G2 (IgG2) was detected in the lambs. Ewes were also immunised with BSA and their isotype specific serum antibody response was compared with their respective lambs. There was no detectable anti-BSA IgM in the lambs of all groups of ewes though specific IgG1 antibodies could be readily detected in the lambs of hyperimmunised ewes. The efficiency of transfer was related directly to the ability of the adjuvant to maximise IgG1 production in the ewe. Although immunised ewes produced high levels of IgG2, this was not transferred passively to the lamb.

Humoral immunity in the ewe. 1. The influence of adjuvancy and immunogenic substitution on immune reactivity following immunisation with protein antigens

The nature of antigen and presence of adjuvant are major factors which influence the level of immune reactivity following immunisation. This study examines the quantity and isotype of antibody produced in ewes immunised with different proteins in combination with different adjuvants. Results using indirect ELISA assays show that animals immunised with keyhole limpet haemocyanin (KLH) in adjuvant produced lower levels (P less than 0.05) of immunoglobulin M (IgM) and had increased levels and persistence of immunoglobulin G1 (IgG1) compared with ewes immunised with antigen in saline (P less than 0.005). The anti-KLH immunoglobulin G2 (IgG2) titre was significantly higher in animals given oil-emulsion adjuvant than all other groups (P less than 0.005). Ewes were also immunised with bovine serum albumin (BSA) or BSA haptenated with trinitrophenyl (TNP) for the primary injection and carrier BSA alone for the secondary inoculation. Chemical haptenation of BSA antigen reduced primary IgM (P less than 0.005), IgG1 (P less than 0.005) and IgG2 (P less than 0.005) levels compared with animals immunised with pure BSA. There was an increased secondary anti-BSA IgM response in all animals first immunised with TNP-BSA (P less than 0.05). The class of anti-hapten antibody produced to TNP determinants was influenced by the degree of TNP haptenation of the carrier BSA. Mid-range molar ratios of TNP produced the strongest IgM, IgG1 and IgG2 anti-TNP responses compared with all other groups (P less than 0.01).

Antibody responses to bacterial antigens in the pregnant ewe

The humoral immune response to the novel antigen Brucella abortus (S19) was examined in nonpregnant ewes and in ewes at different stages of pregnancy. Both the primary and secondary responses were monitored, by measuring the levels of total antibody, Immunoglobulin G (IgG), and complement fixing antibody. Results showed that total antibody production was significantly (p<0.01) impaired in late pregnancy and that IgG titres persisted at significantly (p<0.05) higher levels in non-pregnant animals late in the primary response and following the booster inoculation. Complement fixing antibody levels were significantly higher in non-pregnant ewes and animals inoculated post-partum. These results suggest that active immunity can be altered during pregnancy, with qualitative changes in the class and biological activity of antibody.

Assessing efficiency of passive immune transfer in dairy herds

Blood serum immunoglobulin concentrations of calves during their 2nd wk of life had a .97 correlation with 1st wk concentrations. Correlations between 1st wk concentrations and those in the 3rd, 4th, 5th, and 6th wk of life were .91, .90, .81, and .69. Ten herds were divided into those with mortality rates above and below the median. The major difference in distributions of immunoglobulin concentration between the two groups was percent of calves with concentrations less than 2.5 mg/ml during the 1st wk of life. Calves were sampled monthly for a full year in 19 herds, and all but one herd had one or more calves with immunoglobulin concentrations under 5.0 mg/ml. Overall, calves having immunoglobulin concentrations under 5.0 mg/ml were exposed to excess mortality risk; however, most of the excess risk was concentrated in three herds with high mortality rates (16 to 20%). Evaluating the efficiency of passive immune transfer through the use of management data was unreliable in comparison with assaying serum samples for immunoglobulin concentration.

Characterization of monoclonal antibodies to bovine IgG1

Monoclonal antibodies were developed to bovine IgG1. In addition, production of monoclonal antibodies to bovine light chain is also reported. Monoclonal antibody specificities were initially determined by solid-phase enzyme immunoassay. The monoclonal antibovine IgG1 was shown by a specificity-independent isotyping solid-phase enzyme immunoassay to be mouse IgG1 with kappa light chains. Ascites derived monoclonal antibovine IgG1 antibodies were linked to cyanogen bromide-activated Sepharose and used for affinity isolation of bovine IgG1. The bovine IgG1 eluted from the affinity column was characterized using immuno-electrophoresis, acrylamide gel electrophoresis, isoelectric focusing and solid-phase enzyme immunoassay. Affinity chromatography using monoclonal antibodies provided both a verification of monoclonal antibody specificity and a rapid technique for the isolation of bovine IgG1. This technique may also be employed to remove IgG1 contaminants during purification of bovine IgA.