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assessed as a component of a diagnostic investigation in cows that abort. 5 In these circumstances, detection of an appreciable IgG concentration is deemed suggestive of in utero exposure to pathogens. Detection of low serum concentrations of IgG, IgM

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in American Journal of Veterinary Research

colostrum administration, 8,9 volume of colostrum fed, method of administration, 4 timing of colostral collection, 10 colostral IgG concentration, 11 and dam parity. 11,12 It has been recommended in other reports 4,13,14 that calves should ingest at

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in American Journal of Veterinary Research

SUMMARY

The kinetics of specific IgM and IgG antibody response was characterized in four 9-month-old Beagles after inoculation of 2 × 102 plaque-forming units (pfu) of Sheila Smith strain of Rickettsia rickettsii. Immunoglobulin M antibodies were first detected by indirect immunoflorescence on postinoculation (pi) day 9, peaked by pi day 20, and were no longer detectable by pi day 80. Immunoglobulin G antibodies became detectable between pi days 22 and 28, peaked by pi day 42, and decreased gradually through pi day 130. Subsequent challenges with R rickettsii on pi days 216 (2 × 102 pfu/dog) and 1,029 (5 × 104 tissue culture infective dose [tcid 50]/dog) resulted in slightly different serologic responses. The initial challenge exposure failed to increase the concentration of IgG antibodies and induced only low concentrations of IgM antibodies. After the second challenge inoculation, IgM antibodies were not detectable and the concentration IgG antibodies increased slightly. Clinical abnormalities and seroconversion were documented in control dogs following each challenge exposure.

Examination of acute and convalescent serum samples from 55 dogs in which Rocky Mountain spotted fever was suspected clinically suggested that sole evaluation of IgM antibodies in acute-phase serum would result in inaccurate diagnoses because of false-positive and -negative results. Use of a composite conjugate that detects IgM and IgG antibodies to R rickettsii appears to be satisfactory for diagnostic purposes; however, concurrent quantitation of IgM antibodies may facilitate serodiagnosis in a select group of dogs in which a four-fold increase in convalescent antibody titer is not detected by use of the composite conjugate.

With the exception of a dog with a serum antibody titer of 1:8,192, we were unable to detect IgM or IgG antibodies in csf samples from 9 dogs with experimentally and 3 dogs with naturally acquired infections.

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in American Journal of Veterinary Research

Summary

Polymorphonuclear neutrophils (pmn) from 4 cows were preincubated (30 minutes, 37 C) in either actinomycin D (100 μg/ml) or puromycin (10 μg/ ml), inhibitors of mRNA transcription and protein translation, or in medium 199. The pmn were incubated for a further 4.5 hours in medium containing 100 U of recombinant bovine interferon-γ (rbolfn-γ). The pmn were then incubated with bovine IgG1, IgG2, IgM, or aggregated IgG (algG; 4 C, 12 hours) for flow cytometric analysis, using fluoresceinated is-otype-specific antibody. The percentage of pmn binding the ligand and the logarithmic mean fluorescent channel (lmfc), an indicator of the amount of receptor (R) expression, were recorded. Competitive inhibition of ligand binding was measured by incubating pmn with fluoresceinated IgG2 in the presence or absence of 100-fold excess of IgG1, IgG2, and aIgG. Activation with rboIfn-γ induced a 4.5-fold increase in binding of IgG1 and a fivefold increase in lmfc for IgG2. These increases were inhibited by actinomycin D and puromycin. Percentage of pmn binding aIgG decreased after activation by rboIfn-γ. Interferon-γ treatment did not affect binding or lmfc of IgM. However, binding of IgM was reduced by treatment with actinomycin D. Binding of fluoresceinated IgG2 was inhibited by unlabeled IgG1, IgG2, and aIgG. Results indicate that bovine pmn Fc receptors (FcR) for IgG1 and IgG2 were rboIfn-γ inducible, that induction required de novo transcription and translation, that a heterogeneous population of FcR exist on bovine pmn, and that IgG1 and IgG2 share a common FcR. Further, bovine pmn are capable of gene activation and are responsive to changes in their environment, thus being amenable to modulation for effective pathogen destruction.

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in American Journal of Veterinary Research

Summary

Binding of endogenous and exogenous homologous IgG2 and IgM to bovine neutrophils before and after in vitro migration through micropore filters, and in vivo migration through mammary tissues after intramammary injection of endotoxin was evaluated by use of flow cytometry. Immunoglobulin binding to neutrophils at 4 and 37 C was also evaluated. Before and after in vitro migration, neutrophils with endogenously bound IgG2 and IgM averaged 1 and 2% and 23 and 7%, respectively. Before and after in vivo migration, IgG2 and IgM binding averaged 1 and 7% and 26 and 15%, respectively. Before and after in vitro migration, binding of purified IgG2 and IgM averaged 75 and 67% and 8 and 24%, respectively. Before and after in vivo migration, percentage of neutrophils binding purified IgG2 and IgM averaged 92 and 98% and 54 and 70%, respectively. When serum was used as a source of exogenous immunoglobulins, binding of total IgG after in vitro migration increased from 5% to 28% and of IgM from 4% to 20%. After in vivo migration, binding increased from 21% to 47% and from 24% to 56%, respectively. Exogenous binding of IgG2 at 4 and 37 C averaged 75 and 84%, and binding of IgM averaged 8% at either temperature. Endogenous IgG2 was unaffected by temperature; however, binding of IgM decreased from 23% at 4 C to 2% at 37 C. These data indicate that endogenous binding was higher for IgM before migration than after migration, in vitro and in vivo. Furthermore, migration in vivo through cellular matrices induced receptor upregulation for IgG and IgM. Source and concentration of ligand and serum components, other than immunoglobulins, appeared to contribute to receptor expression and availability. Neutrophils that were exposed to endotoxin and migrated into milk expressed more receptors than did unstimulated and nonmigrating neutrophils. The association of IgM with its receptor was temperature-dependent.

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in American Journal of Veterinary Research

SUMMARY

Over periods of 22 and 14 months, IgG antibody concentrations in serum samples obtained monthly from 14 mares and 19 foals, respectively, were measured by use of elisa against antigens of the following environmental microbes: Aspergillus umbrosus, Penicillium brevicompactum, Rhodotorula glutinis, Absidia corymbifera, Aspergillus fumigatus, Humicola grisea, Micropolyspora faeni, and Thermoactinomyces vulgaris. The mares and foals were on pasture from early June until early October, then were stabled during the winter season until the following June. In the mares, increased antibody concentrations against most microbes were observed typically in midwinter and late spring when the horses were stabled; antibody concentrations against R glutinis, however, peaked in August. Concentrations differed between the summer and winter seasons and, in most instances, between 2 consecutive years and correlated with amounts of rainfall during the previous harvest season. In the foals, circulating passively acquired antibodies disappeared within 3 to 4 months after birth. During the first year of life, substantially increased autogenous antibody concentrations were observed only against R glutinis. Antibody concentrations against the other microbes increased gradually toward the end of the indoor season. In a group of foals transferred indoors in autumn, 6 weeks later than the other foals, antibody concentrations were lower when measured in December. Results supported the view that, to minimize exposure to microbial spores during the winter season, horses should be kept outdoors as much as possible and attention should be focused on improving the ventilation in stables and the quality of feeds and beddings.

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in American Journal of Veterinary Research

SUMMARY

Fifty-four neonatal pigs were allotted to 4 groups and reared in an electrically controlled automatic feeding device (autosow). Each group was reared on a different pool of bovine colostrum: fresh, stored 1 month, stored 6 months, and stored 8 years. Bovine and porcine immunoglobulins in the sera of these pigs, and in a group of conventionally reared pigs, were measured periodically during the first 42 days after birth. The maximal concentration of absorbed bovine immunoglobulin was reached between 12 and 18 hours and equaled or exceeded the amount of porcine immunoglobulin absorbed by the conventionally reared pigs. Large differences in the concentrations of the bovine immunoglobulin isotypes among the various pools of colostrum were positively correlated with concentration of these isotypes in the sera of the neonatal pigs fed these pools. Relative to their concentrations in colostrum, approximately 41% of the IgGl, 55% of the IgG2, 29% of the IgM, and 67% of the IgA was absorbed. The IgA was absorbed the best and IgM was least absorbed. Significant trends or differences in absorption were not observed among groups. Neonatal pigs given fresh colostrum, which had a higher fat content, had significantly more weight gain (P < 0.05). This occurred, despite the fact that the fresh colostrum had the lowest concentration of bovine immunoglobulin. Serum half-lives for bovine IgG1 and IgG2 were significantly less than for porcine IgG (P < 0.05), whereas the half-lives for bovine and porcine IgM and IgA were similar.

De novo-synthesized immunoglobulins were detectable in serum after 6 days; IgM concentrations reached a maximum at 15 days in neonatal pigs given stored, but not fresh, colostrum. The IgG and IgA concentrations steadily increased in all groups and were highest on day 42, when the study was terminated. Neonatal pigs ingesting fresh colostrum had significantly lower concentrations of de novo-synthesized IgG and IgA than pigs fed stored colostrum (P < 0.05). Concentrations in these pigs were also lower than those in conventionally reared pigs. This occurred, despite the lower immunoglobulin concentration in fresh colostrum, and correspondingly, the lower amount of bovine immunoglobulin in pigs that received this colostrum and absorbed it into their serum. In most instances, the amounts of immunoglobulin of any isotype absorbed from stored colostrum and the amount of de novo-synthesized immunoglobulin present 6 weeks later, were inversely correlated. Data indicated that a storage-labile, nonimmunoglobulin factor, in bovine colostrum is able to suppress de novo IgG and IgA synthesis by neonatal pigs.

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in American Journal of Veterinary Research

increases in specific IgG concentrations against these pathogens, which are then passively transferred to calves via colostrum. The purpose of the controlled trial reported here was to determine whether vaccinating cows during late gestation against M

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in American Journal of Veterinary Research

, insufficient transport of immunologic components across the neonatal intestine, characterized by low serum concentrations of maternal IgG in the calf after suckling, is also detrimental. 2 Producers routinely feed frozen colostrum collected from cows on their

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in American Journal of Veterinary Research

Summary

Chicken egg yolk IgG can be absorbed and transferred as efficiently as colostral antibodies in the blood of neonatal pigs. Egg yolk IgG has a half-life of 1.85 days in newborn pig serum. This is shorter than the reported half-life (12 to 14 days) of homologous IgG in serum of pigs. Similar to colostral antibodies, egg yolk IgG absorption from intestine ceased at about 34 hours of age, after a logarithmic decrease in absorption rate from birth. Egg yolk IgG absorption inhibition time in the gastrointestinal tract took 1.73 hours to decrease by half. Egg yolk IgG was protective against experimentally induced diarrhea in pigs when it was administered at high dose, and multiple dosing was instituted. Adverse effects were not observed when chicken egg yolk IgG was administered orally to pigs.

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in American Journal of Veterinary Research