Sensitivity and Specificity Determinations with Isoelectric Focusing Fractions of <i>Blastomyces dermatitidis</i>for Antibody Detection in Serum Specimens from Infected Dogs

Blastomycosis and histoplasmosis manifest as lung and systemic fungal infections in mammals caused by Histoplasma capsulatum, and Blastomyces dermatitidis. These infections exhibit cross reactivity of antibodies which makes a correct diagnosis potentially elusive. The purpose of this study was to gain an understanding of which isoelectric focusing fractions (RotoforTM) of B. dermatitidis were reactive or cross reactive with serum specimens from dogs infected with B. dermatitidis, H. capsulatum, and Cryptococcus neoformans. Three serum specimens from dogs that were infected with B. dermatitidis, two dogs infected with H. capsulatum, and one dog infected with C. neoformans were assayed against the 20 B. dermatitidis RotoforTM fractions. Reactivity was determined using the indirect enzyme linked immunoassay (ELISA). Reactivity with B. dermatitidis was found predominantly in the protein fractions 1 - 6, and cross reactivity with H. capsulatum, and C. neoformans sera was found within the B. dermatitidis protein fractions 15 - 19.

Antigen Detection in Canine Blastomycosis: Comparison of Different Antibody-Antigen Combinations in Two Competitive ELISAs

This present study was designed to evaluate four different Blastomyces dermatitidis antibody-antigen combinations (B5896 and T-58 antibodies and B5896 and WI-R antigens) for the detection of antigen in 36 urine specimens from dogs with blastomycosis using a standard indirect ELISA (STD) and a biotin-streptavidin ELISA (B-SA). The antigen detection sensitivity values ranged from 81% (B-SA: T-58 Ab + WI-R Ag) to 100% (STD and B-SA: B5896 Ab + WI-R Ag;B5896 Ab + B5896 Ag) with the antibody-antigen combinations in the two assays. Optimal detection was evidenced when the B5896 Ab was allowed to react with the urine specimens for 30 min at 37?C and then placed in the B-SA ELISA plates containing the B5896 Ag. The greatest absorbance value obtained with this antibody-antigen com-bination was 0.903 (range of 0.596 - 0.903) as compared to the control value of 1.246. The difference between the control absorbance and the test absorbance values was 0.343 which was considerably greater than the control-test values with the other combinations. This study thus showed that the results obtained in antigen detection assays are dependent upon the antibody used to react with the urine specimens as well as the antigen used in the enzyme immunoassay.

Comparison of Antibody Detection with Yeast Lysate Antigens Prepared from Blastomyces dermatitidis Dog Isolates from Wisconsin and Tennessee

Blastomyces dermatitidis, the causative agent of blastomycosis, a potentially lethal dimorphic fungal disease of humans and animals has been difficult to diagnose in the clinical laboratory. We are attempting to develop and improve immunodiagnostic assays by producing novel yeast lysate reagents for the detection of antibodies in blastomycosis. The objective of this study was to use lysate antigens prepared from four B. dermatitidis antigens isolated from dogs infected with blastomycosis from two different endemic areas (Wisconsin and Tennessee) testing for the detection of antibodies in serum specimens from immunized rabbits and infected dogs using the indirect ELISA. In the dog sera, absorbance values ranged from 0.774 to 1.350, while the rabbit sera values ranged from 0.533 to 1.191. Antigen T-58 appeared to lack any geographical specificity in antibody detection, which could prove useful in future immunodiagnostic detection of blastomycosis infections.

Blastomyces dermatitidis: Stability studies on different yeast lysate antigens

In Trial 1, 19 lots of Blastomyces dermatitidis (T-58;Tennessee dog isolate) were assayed to determine the stability of the reagents following storage. The reactivity of the antigens, produced from 1989 to 2012 and stored at 4°C, was determined by comparing antibody detection (enzyme-linked immunosorbent assay;ELISA) in 12 serum specimens from immunized rabbits. All of the 19 reagents produced during this 23-year period exhibited a high degree of stability and were able to detect antibody in the sera. Mean absorbance values ranged from 0.798 (1989) to 0.827 (2012) and a mean value for all 19 antigens of 0.728. In a related evaluation, Trial 2, B. dermatitidis lysate antigens prepared from 8 isolates (dog, human, soil) at two different time periods were assayed as above to determine reactivity. The time of storage between the first and second reagents varied from 4 to 17 years. The results indicated that all 16 of the lysate antigens detected antibody in the 15 rabbit serum specimens with mean absorbance values ranging from 0.346 to 0.682, but variations in reactivity were observed depending on the lysate and the serum specimen assayed. This comparative study provided evidence that the antigenic reagents do exhibit some lot-to-lot variation in reactivity, but they did not lose any appreciable potency during prolonged storage.

Comparison of Detection of Antibodies with Yeast Lysate Antigens Prepared from Two Isolates of <i>Blastomyces dermatitidis</i>by Two Different Methods: Sensitivity and Specificity Evaluations

Blastomycosis, a systemic fungal disease, caused by the dimorphic fungus Blastomyces dermatitidis, has continually presented clinicians with concerns with regard to laboratory diagnosis and prevention. For years researchers have strived to develop antigens with a high degree of sensitivity and specificity. The purpose of this study was to gain a bet- ter understanding of how two novel yeast lysate antigens, prepared from two B. dermatitidis isolates by different meth- ods, would be able to detect antibody responses in immunized rabbits in a specific and sensitive manner. The en- zyme-linked immunosorbent assay (ELISA) was used to evaluate antibody in serum specimens with yeast lysate re- agents prepared after allowing yeast cells to lyse for 1 or 7 days. The results indicated that reactivity was greater with the day 7 antigens, with both the B5896 and 597 B. dermatitidis isolates, when compared to the day 1 antigens;in con- trast the day 1 preparations exhibited less cross reactivity when assayed against anti-Histoplasma capsulatum serum specimens.

Detection of Antibody in Dogs with Blastomycosis Using <i>Blastomyces dermatitidis</i>Yeast Phase Lysate Antigens

The objective of our study was to compare two B. dermatitidis yeast phase lysate antigens [ERC-2, dog Wisconsin;85, soil Georgia, ATCC 56,920] for detecting antibody in 38 serum specimens [pre-treatment, 30-day, and 60-day post treatment] from dogs with diagnosed blastomycosis. The mean absorbance values obtained with the two antigens (N = 38) were ERC-2 = 2.359 and 85 = 2.189. The mean absorbance values when the sera were divided into the three treatment groups were as follows pre-treatment: Isolate ERC-2 had an absorbance value of 2.418;Isolate 85 had an absorbance value of 2.688, 30-day post treatment: ERC-2 had an absorbance value of 2.452;85 had an absorbance value of 2.303 and 60-day post treatment: ERC-2 had an absorbance value of 2.150;85 had an absorbance value of 2.073 with the mean absorbance values of all treatment groups were ERC-2: 2.229 and 85: 2.141. This study indicates the potential for further evaluations of the two lysate antigens with regard to antibody detection in dog sera with the ERC-2 reagent slightly more reactive than the 85 lysate antigen.

Detection of Antibodies in Serum Specimens from Dogs with Blastomycosis with Lysate Antigens Prepared from Four <i>Blastomyces dermatitidis</i>Dog Isolates: Individual Antigens vs Antigen Combinations

Blastomycosis, the systemic fungal infection of humans and animals, has presented a diagnostic challenge to clinicians and laboratory personnel for many years. Our laboratory has been concentrating on attempting to develop antigenic reagents from the yeast phase of various isolates of Blastomyces dermatitidis and to evaluate these lysate antigens with regard to antibody detection in blastomycosis. The aim of this current study was to evaluate yeast phase antigens prepared from four dog isolates of B. dermatitidis and to evaluate their efficacy, when used individually or in combination, for antibody detection in sera from dogs with blastomycosis. Mean absorbance values using the ELISA to assay 24 serum specimens (Trial 1) ranged from 0.588 with an individual lysate antigen to 0.992 when three reagents were combined. Eight of the lysates exhibited mean absorbance values ranging from 0.992 to 0.915 with 7 out of 8 being lysate antigen combinations. Mean absorbance values with the other 6 lysates ranged from 0.899 to 0.588. In Trial 2, the 6 most sensitive reagents from Trial 1 were assayed against 10 highly reactive dog sera. The results of Trial 2 showed that 5 antigen combinations detected antibody to a greater degree than the individual lysate antigen. Combinations of northern and southern antigens were able to detect antibody in serum specimens from either of these geographical regions. Comparative studies are continuing to further evaluate various lysate antigen combinations for antibody detection in blastomycosis.

<i>Blastomyces dermatitidis</i>: Chitinase Homology Model, <i>in Silico</i>Docking, and Inhibition Assay

Blastomyces dermatitidis is a thermally dimorphic fungus that causes the disease blastomycosis. Currently there are a limited number of effective treatments, many of which have harsh side effects. Chitin, a component of the fungal cell wall is often broken down and recycled for cell wall remodeling and growth. Chitinase is the digestive enzyme capable of chitin hydrolysis. By inhibiting the chitinase we predicted that cells wouldn’t be able to divide and multiply normally, thereby leading to possible anti-fungal treatments. For this study we modeled the structure of B. dermatitidis chitinase, using homology modeling. By predicting a three-dimensional structure we were able to do additional analyses of the active site of the chitinase and predict the binding of a possible small molecule, acetazolamide, in silico. This binding allowed us to predict that this molecule might be capable of inhibiting the chitinase of B. dermatitidis. This inhibition was tested in vivo. No difference in the growth curves of the test and control organisms was observed, however there was a difference within the cell walls of the yeast cells. The cell walls appeared thicker with additional differences in cell wall orderly growth. These changes are consistent with changes that may occur as B. dermatitidis chitinases are inhibited.

Comparison of Two Enzyme Immunoassays and Four Lysate Antigens for the Detection of Antibody in Canine Blastomycosis

Blastomycosis, the systemic fungal disease of humans and animals caused by Blastomyces dermatitidis and the cryptic species Blastomyces gilchristii, is often misdiagnosed as a bacterial or viral pulmonary disease. Therefore, the development of improved immunodiagnostic assays for this disease has been the primary focus of research in our laboratory. The present study was designed to evaluate four Blastomyces yeast-phase lysate antigenic preparations (human, 597, Eagle River, WI;dog, ERC-2, WI;Human, B5927, Mountain Iron, MN;soil, 85, Georgia, ATCC 56920) for their ability to detect antibody in 48 serum specimens from dogs with diagnosed blastomycosis using an indirect ELISA (STD) compared to a biotin-streptavidin ELISA (B-SA). All four lysate antigens were able to detect antibodies in the specimens with mean absorbance values ranging from 0.930 (B5927) to 1.142 (ERC-2) with the STD ELSA and from 1.395 (B5927) to 1.775 (85) with the B-SA ELISA. The results indicated that both ELISA methods could be utilized for antibody detection, but the B-SA ELISA exhibited greater sensitivity than the STD ELISA with all four of the lysates.

Comparison of antibody detection with <i>Blastomycesdermatitidis</i>yeast lysate antigens in serum specimens from immunized rabbits and infected dogs

This present study was designed to evaluate B. dermatitidis antigens, prepared from two isolates (B5896, 597), when the yeast cells were allowed to lyse in distilled water for one day or seven days. The indirect enzyme-linked immunosorbent assay (ELISA) was used to determine the ability of the lysate reagents to detect antibodies in 30 rabbit and 30 dog serum specimens. Mean absorbance values with B5896 lysate antigen ranged from 1.637 (day 1) to 1.461 (day 7) and absorbance values with 597 antigen ranged from 1.579(day 1) to 1.396 (day 7) with the serum specimens from immunized rabbits. Serum specimens from infected dogs yielded absorbance values ranging from 1.672 (day 1) to 1.763 (day 7) with the B5896 and values ranging from 1.909 (day 1) to 1.224 (day 7) with the 597. Optimal reactivity was obtained with the day 1 lysate using both lysate antigens against the rabbit sera and with the 597 antigen against the dog sera. Slightly greater reactivity was evidenced with the day 7 B5896 antigen when the dog sera was tested. Comparative studies are continuing in order to produce an optimal anti-genic preparation for antibody detection in blastomycosis.