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SUMMARY

Enzyme-linked immunosorbent assays for the detection of Toxoplasma gondii antigen-containing IgM immune complexes (T gondii-specific IgM-lC) and IgG immune complexes (T gondii-specific IgG-IC) in the serum of cats were developed. Serum from clinically ill, naturally infected cats; healthy, naturally infected cats; and healthy cats experimentally inoculated with T gondii was assayed. All combinations of T gondii-specific IgM, IgG, antigens, IgM-IC and IgG-IC were detected in naturally infected and experimentally infected cats. Clinically ill cats and cats with ocular signs of toxoplasmosis were more likely than healthy cats to have Tgondii-specific IC in serum. It was concluded that T gondii-specific IC form in the serum of cats, may play a role in clinical disease development, and affect the results of Tgondii-specific IgM, IgG, and antigen serologic assays.

Free access
in American Journal of Veterinary Research

Summary

Capsular polysaccharide (cp) of Pasteurella haemolytica, biotype A, serotype 1, was purified and combined with saline solution, aluminum hydroxide, and Freund's incomplete (oil) adjuvant. Three groups of calves were administered the various antigen preparations. The cp in saline preparation was also administered to 5 mature cows. Second injections were given 4 weeks after the first. Weekly obtained serum samples were analyzed for P haemolytica-specific antibody, using the indirect hemagglutination assay, and cp-specific antibodies were detected, using an isotype-specific elisa. Purified cp stimulated production of cp-specific IgM, IgG1, and IgG2 in calves and predominantly IgM and IgG1 in mature cows. Significant increases in cp antibody titers were not observed after the second injection of cp antigen in either calves or mature cows. The cp in oil adjuvant stimulated the highest mean cp-specific IgG1 and IgG2 responses, whereas the cp in aluminum hydroxide adjuvant stimulated the highest mean cp-specific IgM response.

Free access
in American Journal of Veterinary Research

vaccine will not cause clinical signs of strangles in vaccinated ponies, will result in increased concentrations of serum anti- S equi IgG, will not be recovered at > 3 days after vaccination or administration of a booster vaccination, and will not result

Full access
in American Journal of Veterinary Research

SUMMARY

In an attempt to identify important predictors of failure of passive immunoglobulin transfer (< 800 mg of IgG/dl), identify calves with failure of passive immunoglobulin transfer, and determine the effects of a colostrum supplement, blood samples were collected from 263 calves at postpartum hours 10 and 24. Calves of dams diagnosed with mastitis had lower mean plasma protein and IgG concentrations at 10 (P < 0.05) and 24 (P < 0.01) hours. Plasma protein and IgG concentrations were similar for single and twin calves at 10 hours, but IgG concentration at 24 hours was higher (P < 0.01) in twin calves. Calves born to dams that had dystocia had numerically lower mean plasma protein and IgG concentrations than did calves born to dams that had normal delivery. However, observed differences were small and, after adjustment for other important factors, these differences were not significant. Age of dam was associated with plasma protein (P < 0.05) and IgG (P < 0.10) concentrations at 10 hours, but had no effect at 24 hours. Plasma protein and IgG concentrations decreased as calves were born later in the calving season, although the association of birth date with IgG concentration at 24 hours was marginal (P = 0.07). Calf sex, dam body condition score, and birth weight were not related to plasma protein or IgG values. The sensitivity and specificity of a cutoff value of 4.8 g of protein/dl of plasma, measured at 10 hours, for diagnosing failure of passive immunoglobulin transfer at 10 hours were 78 and 94%, and for diagnosing failure of passive immunoglobulin transfer at 24 hours were 88 and 73%, respectively. A colostrum supplement administered to calves with low plasma protein concentration at 10 hours had no effect on plasma protein or IgG values at 24 hours or on pre-weaning morbidity and mortality.

Free access
in American Journal of Veterinary Research

SUMMARY

Intraocular production of Toxoplasma gondii-specific antibody in cats has been estimated by comparing the ratio of T gondii-specific antibody in aqueous humor and serum with the ratio of total immunoglobulins in serum and aqueous humor (Goldmann-Witmer coefficient; aqueous antibody coefficient; C value). It has been proposed that in human beings, comparison of the ratio of T gondii-specific antibody in aqueous humor and serum with the ratio of antibodies against a nonocular pathogen in serum and aqueous humor is more accurate than methods using total immunoglobulin quantification. We developed an elisa for detection of calicivirus-specific antibodies in the serum and aqueous humor of cats. By evaluating calicivirus-specific antibody concentrations in the aqueous humor of healthy and diseased cats, calicivirus was assessed as a nonintraocular pathogen. The ratio of T gondii-specific antibodies in the aqueous humor and serum and the ratio of calicivirus-specific antibodies in serum and aqueous humor were evaluated as a means of estimating intraocular T gondii-specific antibody production.

A field strain of feline calicivirus was isolated, cultured, and purified. A calicivirus-specific IgG elisa was developed for detection of feline calicivirus-specific IgG in serum and aqueous humor. Calicivirus-specific IgG was measured in the serum and aqueous humor from 3 groups of control cats. Results suggested that calicivirus is a nonintraocular pathogen in cats and that calicivirus IgG detected in aqueous humor is attributable to leakage across a damaged blood-ocular barrier.

Intraocular production of T gondii-specific antibodies was estimated, using 2 formulas. The C value was calculated by multiplying the ratio of T gondii-specific IgM or IgG in aqueous humor and serum by the ratio of total immunoglobulins (using the corresponding IgM or IgG class) in serum and aqueous humor. The C tc value (Toxoplasma-calicivirus Goldmann-Witmer coefficient) was calculated by multiplying the ratio of T gondii-specific IgM or IgG in aqueous humor and serum by the ratio of calicivirus-specific IgG in serum and aqueous humor.

Serum and aqueous humor samples were obtained from 41 client-owned cats with uveitis, and T gondii-specific C values and Ctc values were calculated. Toxoplasma gondii-specific IgM or IgG C values of 10 or greater or T gondii-specific IgM or IgG Ctc values of 1 or greater were considered to be suggestive of intraocular T gondii-specific antibody production. Of the 41 cats, 20 (48.7%) had evidence of intraocular production of T gondii-specific antibody on the basis of either an IgM or IgG C value of 10 or greater. A Ctc value could not be calculated in 3 cats because calicivirus-specific IgG was not present in aqueous humor. Of the 38 cats for which Ctc values could be calculated, 25 (65.8 %) had evidence of intraocular production of T gondii-specific antibody on the basis of either an IgM or IgG Ctc value of 1 or greater. The C values and Ctc values were in agreement for 75.9 % of IgM containing samples and 75% of IgG containing samples. Sensitivity, specificity, predictive value of a positive test result, and predictive value of a negative test result for an IgM or IgG C value, when compared with the corresponding IgM or IgG Ctc value were determined. The results indicate that use of the C value for estimation of intraocular T gondii-specific antibody production will result in 28.6 (IgM) to 50 % (IgG) false-negative results and 12.5% (IgM and IgG) false-positive results, when compared with the Ctc value.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether passive transfer of IgG in neonatal kittens affects plasma opsonic capacity and neutrophil phagocytic and oxidative burst responses to bacteria in vitro.

Animals—22 kittens from 6 specific pathogen-free queens.

Procedure—Kittens were randomized at birth into the following treatment groups: colostrum-fed, colostrum-deprived, or colostrum-deprived supplemented with feline or equine IgG. Blood samples were collected at intervals from birth to 56 days of age. Plasma IgG concentrations were determined by radial immunodiffusion assay. Neutrophil function was assessed by a flow cytometry assay providing simultaneous measurement of bacteria-induced phagocytosis and oxidative burst. The opsonic capacity of kitten plasma was determined in an opsonophagocytosis assay with bacteria incubated in untreated or heat-inactivated plasma.

Results—Among treatment groups, there were no significant differences in neutrophil phagocytic and oxidative burst responses to bacteria or opsonic capacity of plasma. In all samples of plasma, inactivation of complement and other heat-labile opsonins significantly reduced the opsonic capacity. Plasma IgG concentrations in kittens did not correlate with neutrophil function or plasma opsonic capacity before or after inactivation of complement.

Conclusions and Clinical Relevance—The plasma opsonic capacity and neutrophil phagocytic and oxidative burst responses in vitro of kittens receiving passive transfer of IgG via colostrum intake or IgG supplementation and those deprived of colostrum were similar. The alternate complement pathway or other heat-labile opsonins may be more important than IgG in bacterial opsonization and phagocytosis. ( Am J Vet Res 2003;64:538–543)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine regional seroprevalence estimates of Toxoplasma gondii-specific IgM and IgG in clinically ill cats throughout the United States.

Sample Population—Sera from 12,628 clinically ill, client-owned cats.

ProcedureToxoplasma gondii-specific IgM and IgG antibodies were detected by use of ELISAs. Sera from clinically ill cats previously submitted for T gondii antibody testing were sequentially selected from our serum bank and the sample submission paperwork reviewed. The country was divided into 12 geographic regions. Overall prevalence as well as prevalence for each region, age group, season, sex (male vs female), and breed (domestic shorthair vs other) was calculated. Data were analyzed by logistic regression analysis.

Results—Overall, 31.6% of the cats were seropositive for T gondii-specific IgM, IgG, or both. Percentage of cats seropositive for T gondii antibodies ranged from 16.1% (southwestern United States) to 43.5% (northeastern United States). As age increased, odds of positive T gondii antibody assay results (IgM alone, IgG alone, and any combination of IgM or IgG) increased. Males were more likely than females to be seropositive for T gondii antibodies (IgG alone and any combination of IgM or IgG). Domestic shorthair cats were more likely than other breeds to be seropositive for T gondii antibodies (IgM alone, IgG alone, and any combination of IgM or IgG).

Conclusions and Clinical RelevanceToxoplasma gondii-specific antibodies are common in serum samples of clinically ill cats from all regions of the United States. Seroprevalence increases as cats age and is higher in male and domestic shorthair cats, compared with females and other breeds. (Am J Vet Res 2005; 66:874–877)

Full access
in American Journal of Veterinary Research

Summary

To determine the suitability of a new colostrum substitute derived from goat serum and to determine the amount of colostral IgG needed to achieve serum IgG concentration > 800 mg/dl, twin kids from 14 does were fed colostrum or a colostrum substitute. The volume of colostrum or colostrum substitute fed was calculated so that half the kids in each group received IgG at a low dosage (1.5 g/kg of body weight) and the other half received IgG at a high dosage (3 g/kg). Kids were bottle fed the colostrum or colostrum substitute and then fed pooled goat's milk until 18 hours old, at which time they were allowed to nurse their dams. Does were milked manually every 2 hours after parturition until specific gravity of mammary secretions was < 1.02, the specific gravity of goat's milk. Serum IgG concentration of each kid was determined by means of single radial immunodiffusion at birth and 12, 18, and 24 hours and 7, 21, and 42 days after birth. Kids were weighed at each blood collection and monitored for illness daily.

None of the kids had measurable serum IgG concentrations at birth. Mean serum IgG concentration was significantly higher in kids fed colostrum than in kids fed colostrum substitute at all times, except days 7 and 42 (P < 0.05). By 24 hours after birth, serum IgG concentration was > 800 mg/dl in all kids fed colostrum, in 4 of 7 kids fed the substitute at the higher dosage, and in 2 of 7 kids fed the substitute at the lower dosage. Serum IgG concentration decreased in all kids during the first 21 days after birth, but was increased by 42 days. Mean body weight did not differ between groups; none of the kids became ill. Kids willingly suckled the colostrum and colostrum substitute, but the substitute had to be diluted with water because of its thick consistency.

Free access
in Journal of the American Veterinary Medical Association

Summary

Effects of farm management, breed, mare age, gestation duration, and climatologic factors on colostral specific gravity, colostral IgG concentration, and foal serum IgG concentration were evaluated. Climatologic variables measured were daily maximal, minimal, and mean air temperature, precipitation, average relative humidity, and total solar radiation. Presuckle, postpartum colostrum samples were collected from 140 Standardbred, 94 Thoroughbred, and 59 Arabian mares from January through June during 1985 and 1986. Thoroughbred (farm A, n = 61; farm B, n = 33) and Arabian (farm C, n = 45; farm D, n = 14) mares were located in Ocala, Fla; Standardbred mares (farm E) were in Montgomery, NY. Mares from farms A, B, D, and E foaled in box stalls, and mares from farm C foaled in sand paddocks. Mares with premature lactation >12 hours were not included in the study. Foals were clinically normal at birth and suckled colostrum without assistance within 2 hours of parturition. Specific gravity of presuckle colostrum samples was measured by use of an equine colostrometer. Blood samples were collected 18 hours after parturition from 253 of the 293 foals (n = 45, 25, 32, 13, 138 on farms A through E, respectively) to determine serum concentration of IgG. The IgG concentrations in colostrum and serum were measured by single radial immunodiffusion. Data were analyzed by multiple regression or Χ2 analysis.

The most important determinants of foal serum IgG concentration were the IgG content and specific gravity of presuckle colostrum samples (P < 0.0001). Colostral IgG concentration was highest in mares 3 to 10 years old, and mean values were higher in Thoroughbred and Arabian mares than in Standardbred mares (P < 0.01). Failure of passive transfer (serum IgG concentration <400 mg/dl) was observed in 13% of the foals, and highest prevalence was in foals that suckled mares >15 years old (P < 0.001). Seventy percent of foals whose dams were <15 years old had serum IgG concentration >800 mg/dl, whereas only 45% of foals whose dams were >15 years old had serum IgG concentration >800 mg/dl. Farm management affected passive transfer of IgG; mares from farm D had the highest mean colostral specific gravity, but their foals had the lowest mean serum IgG concentration (P < 0.01). Arabian foals born between 335 and 345 days of gestation had the highest mean serum IgG concentration; values decreased in bell-shape fashion as gestation duration increased or decreased. Similar pattern was observed for colostral specific gravity and IgG concentration of Arabian and Thoroughbred mares. Total solar radiation was the only climatologic variable that affected IgG concentration in colostrum or foal serum. Only horses on farm E (temperate environment) were affected. As total solar radiation increased, IgG concentration in colostrum and foal serum increased. These results indicate that foals from dams >15 years old, foals whose dams have a colostral specific gravity <1.06, and foals born in cold, wet environments may need supplemental colostrum to prevent failure of passive transfer. Farm management, premature birth, and birth after day 345 of gestation may adversely affect absorption of colostral IgG in foals.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the associations between serum IgG concentration and serum activities of γ-glutamyltransferase (GGT), alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and pseudocholinesterase for the potential use of these serum enzymes as predictors of passive transfer status in neonatal lambs.

Design—Prospective observational study.

Animals—47 Sardinian lambs from birth to 2 days old.

Procedure—Serum enzyme activities were measured by use of commercially available kits and a clinical biochemical analyzer. Serum IgG concentration was determined by single radial immunodiffusion. Associations between serum IgG concentration and the activity of each serum enzyme were established by use of regression analysis.

Results—A significant correlation was detected between serum IgG concentration and serum GGT activity in 1- and 2-day-old lambs. Minimal correlations were detected between serum IgG concentration and serum alkaline phosphatase activity in 1-dayold lambs and serum pseudocholinesterase activity in 1- and 2-day-old lambs. No significant associations were detected between serum IgG concentration and serum activities of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. A multiple linear regression model was accurate for the estimation of the natural logarithm of serum IgG concentration as a function of the natural logarithm of serum GGT activity and of the age of lambs at the time of sampling (adjusted R 2 = 0.89). This model was then used to calculate the serum GGT activity equivalent to various serum IgG concentrations for 1- and 2-day-old lambs.

Conclusions and Clinical Relevance—Results suggested that passive transfer status in neonatal lambs can be successfully predicted by measurement of serum GGT activity but not by measurement of the other enzymes tested. (J Am Vet Med Assoc 2005; 226:951–955)

Full access
in Journal of the American Veterinary Medical Association