Determination of antibody titers against soluble antigen by indirect fluorescent antibody (IFA) assay using latex particles coupled with soluble antigen: a preliminary study.

A method for indirect fluorescent antibody (IFA) assay for soluble antigen has been developed using latex particles (latex) as a carrier for soluble antigen. Two types of latex having grain sizes of 1.0 and 6.0 µm were used for IFA assay and were evaluated in this study. Bovine IgG and rabbit anti-bovine IgG antibody were used as soluble antigen and as primary antibody, respectively. Bovine IgG-sensitized latex on slide glass was not washed off after immersion for 45 min. IFA using latex appears to have high specificity, as no reactions between fluorescein isothiocyanate (FITC)-conjugated antibody and protein-sensitized latex were observed, and the latex did not show auto-fluorescence or non-specific reactions. Latex with a grain size of 6.0 µm was appropriate as a carrier of soluble antigen, as the amount of soluble antigen necessary for sensitization was approximately one-eighth that necessary for the small-diameter latex (1.0 µm), and large-diameter latex is easier to distinguish under the fluorescence microscope. IFA assay using soluble antigen-sensitized latex is suitable for more widespread use in the future.

Alpha 1-acid glycoprotein (AAG) levels in healthy and pregnant beagle dogs.

Serum alpha 1-acid glycoprotein (AAG) levels were measured in healthy beagles of various ages (66 male and 74 female) by turbidimetric immunoassay (TIA), and then separately--in pregnant beagles--by single radial immunodiffusion (SRID). The first experiment revealed that serum AAG levels ranged from 40 to 960 microg/ml (mean of 322 +/- 202 microg/ml) in male dogs, and from 47 to 833 microg/ml--in female dogs (mean of 316 +/- 199 microg/ml), without any significant sex- or age-related variation. The second experiment, however, revealed that serum AAG levels increased in all pregnant beagles and peaked in the middle of gestation at 250-1,000 microg/ml (mean of 634 +/- 246 microg/ml). In 7 of 8 dogs the AAG levels peaked about 45 days after ovulation. Despite a high value of 1,210-1,360 microg/ml being observed for serum AAG levels in 3 pregnant beagles inoculated with Staphylococcus aureus, its levels in umbilical cord blood were below the detection limit of SRID (40 microg/ml).

Determination of serum C-reactive protein (CRP) in healthy beagle dogs of various ages and pregnant beagle dogs.

Serum C-reactive protein (CRP) concentrations in healthy beagle dogs of various ages and in pregnant beagles were measured by enzyme-linked immunosorbent assay (ELISA). Serum CRP concentrations were 1.5-16.0 microg/ml (mean 7.9 +/- 3.4 microg/ml) in male, and 1.8-18.9 microg/ml (mean 8.3 +/- 4.0 microg/ml) in female dogs. No significant sex-related differences were observed in the values. Further, there were no significant age-related differences either. Serum CRP concentrations increased during pregnancy. The concentration of serum CRP in pregnant dogs peaked at 70.2-90.4 microg/ml (mean 77.5 +/- 7.1 microg/ml) 30 or 45 days after ovulation, demonstrating two characteristic features of CRP concentration change in pregnant dogs.