Biomedical subjects

D B Snyder

Publications and source records attributed to D B Snyder.

At least 37 records · Page 2Linked to original sources

PubMedDate not supplied

An immunoperoxidase monoclonal antibody stain for rapid diagnosis of infectious bursal disease.

Cell smears of chicken-embryo-fibroblast (CEF) cultures and bursa of Fabricius from chickens experimentally infected with six different strains of infectious bursal disease virus (IBDV) were examined for the presence of IBDV by the avidin-biotin-peroxidase complex method of immunoperoxidase (IP) staining using a monoclonal antibody specific for IBDV designated BK70. IBDV of different strains and serotypes were readily detected by the IP method in cell smears prepared from infected CEF cultures and from bursas. Bursal cells were positive for IP stain in most of the infected bursas (87.5%), despite their mild IBD lesions. Positive IP staining of bursal smears was well correlated with the recovery of IBDV from the bursas and with IBD lesions in the bursas. IP stain with a monoclonal antibody (BK70) appeared potentially useful for rapid and definitive diagnosis of IBD.

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PubMedDate not supplied

Differentiation of infectious bursal disease viruses directly from infected tissues with neutralizing monoclonal antibodies: evidence of a major antigenic shift in recent field isolates.

Two neutralizing monoclonal antibodies (MCAs), R63 and B69, were used in antigen-capture enzyme immunoassays to verify the presence of infectious bursal disease virus (IBDV) in infected bursal tissues. The intra-serotype-common neutralization site defined by the R63 MCA was present on all IBDV isolates and laboratory strains tested. However, the neutralization site defined by the B69 MCA was found on only classic or older IBDV strains; it was not found on recently isolated variants of IBDV or on a majority of recent field viruses examined. The data suggest that a major antigenic shift in IBDV has occurred in the field and that this shift involves, at a minimum, the deletion or alteration of one of two neutralization sites previously found on classic IBDV strains.

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PubMedDate not supplied

Group and strain-specific neutralization sites of infectious bursal disease virus defined with monoclonal antibodies.

Two somatic cell hybridizations were performed utilizing splenocytes from mice immunized with one or more strains of infectious bursal disease virus (IBDV). Supernatants from hybridoma cell lines were initially screened by the enzyme-linked immunosorbent assay (ELISA) against multiple strains of IBDV. Cell lines that secreted antibodies with ELISA reactivity patterns of interest were cloned, and their monoclonal antibodies (MCAs) were subsequently tested in cross-virus-neutralization tests. Two of the nine MCAs selected exhibited strong neutralizing activity and precipitated IBDV antigens in agar gel precipitin tests as well. MCA B69 significantly neutralized only the cloned D78 strain of IBDV, whereas MCA R63 neutralized all IBDV strains (representing both serotype I and II viruses) against which it was tested. Results of competitive ELISAs that used the R63 and B69 MCAs showed that the two neutralization sites on the D78 strain were not overlapping.

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PubMedDate not supplied

Rapid serological profiling by enzyme-linked immunosorbent assay. IV. Association of infectious bursal disease serology with broiler flock performance.

Breeder and broiler flocks were serologically evaluated using a multiple enzyme-linked immunosorbent assay (M-ELISA). The serologic status of two commercial broiler-breeder flocks and their progeny was monitored, and 840 sera were promptly assessed for antibodies against six infectious agents using the M-ELISA. Breeder flocks were sampled at lay, and broiler chicks were hatched from fertile eggs collected on the scheduled lay date of the breeders. The broiler chicks were placed for growout as eight separate flocks (four from each breeder), and the serologic survey of broilers included sequentially sampling each flock five times between 1 day of age and market. Association of broiler vaccination schedules, mortality, and condemnation data with the temporal serologic data obtained indicated that the earlier appearance of active antibody against infectious bursal disease (IBD) in some unvaccinated flocks was associated with subsequent higher growout mortality and with the poorer overall performance that these flocks experienced. The results of this serologic survey also demonstrated that if a constant, well-timed monitoring program had not been used, major serologic differences between flocks would not have been detected. Serologic profiles of selected broiler flocks by virus-neutralization (VN) tests for infectious bronchitis virus (IBV) and reovirus or by hemagglutination-inhibition (HI) tests for Newcastle disease virus (NDV) compared favorably with the serologic profiles obtained by M-ELISA. Comparison of vaccination histories with serologic results derived from M-ELISA, VN or HI tests indicated that response to vaccination for IBV and NDV at 1 day was either blocked or significantly delayed by moderate levels of maternal antibody and/or were suppressed by an apparent field outbreak of IBD that occurred in all eight broiler flocks.

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PubMedDate not supplied

Characterization of a battery of monoclonal antibodies for differentiation of Newcastle disease virus and pigeon paramyxovirus-1 strains.

Twenty monoclonal antibodies (MCAs) prepared against the velogenic GB-Texas strain of Newcastle disease virus (NDV) and the type 1 pigeon paramyxovirus (PPMV-1) were characterized and examined as potential immunodiagnostic reagents. All MCAs generated were found to bind specifically, but with varying reactivity, to various NDV strains in direct binding assays. In addition, MCA 15C4 neutralized and inhibited hemagglutination (HA) of all lentogenic, mesogenic, and velogenic NDV strains tested but not the PPMV-1 strain. Antibody 10D11 also inhibited HA activity, but inhibition was more selective and limited to the mesogenic and domestic or indigenous velogenic strains of NDV. MCA 79 reacted in all serologic assays with an antigenic site common to all serotype 1 avian paramyxoviruses. Passive immunization studies involving three different neutralizing MCAs (35, 79, and 15C4) showed that enhanced, but not complete, protection against virulent NDV challenge was provided when the three MCAs were administered in combination.

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PubMedDate not supplied

Latest developments in the enzyme-linked immunosorbent assay (ELISA).

Enzyme-linked immunosorbent assays (ELISAs) for the serologic detection of both antigen and antibody in monitoring programs of commercial poultry flocks have begun to be recognized as an improvement over more conventional diagnostic procedures. The feasibility of employing double-antibody sandwich assays for the detection of virus without prior isolation of virus has been demonstrated and shows promise as the method of choice for the detection of lymphoid leukosis virus shedding. The versatility of indirect ELISA for the measurement of antibody induced by a wide variety of potential pathogens using a single basic overlapping ELISA system has also been demonstrated. It shows potential as a likely candidate to replace some of the more costly and time-consuming or less sensitive conventional serologic methods that do not overlap. Although some aspects of the two major types of immunoassays currently used in poultry health may need some modifications or improvements before delivery for routine use, it is likely that the use of computer-assisted ELISA will gain increased acceptance and use as the preferred way to efficiently and accurately monitor the health of poultry flocks on a broad scale.

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PubMedDate not supplied

An enzyme-linked immunosorbent assay for the detection of antibody against avian influenza virus.

An enzyme-linked immunosorbent assay (ELISA) was developed for detecting antibody to type A avian influenza (AI) virus. The sensitivity and group specificity of the AI-ELISA were compared with those of the agar-gel-precipitin test (AGPT) and the hemagglutination-inhibition (HI) test under conditions of both controlled and field exposure. During the course of temporal experimental infection (0-76 days) of specific-pathogen-free (SPF) chickens with AI subtype Hav9N2, the AI-ELISA was able to detect specific AI antibody as early as 8 days postinoculation (PI), and it measured rising levels of antibody through 35 days PI, at which time the chickens were re-exposed to AI virus. Conversely, AGP tests were negative through 35 days PI, and HI tests began to detect low levels of AI antibody only at 21 days PI. Following a secondary infection at 35 days PI with the same AI subtype, all tests measured rising levels of AI-specific antibody (35-76 days PI). However, the AGP test was positive at only the 7- and 14-day samplings postsecondary immunization. Under field conditions, the AI-ELISA was able to detect serum AI antibody in flocks from which highly pathogenic AI was isolated, but the AGP tests of these sera were negative.

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PubMedDate not supplied

Antibody response to Newcastle disease virus given by two different routes as measured by ELISA and hemagglutination-inhibition test and associated tracheal immunity.

The enzyme-linked immunosorbent assay (ELISA) and the conventional hemagglutination-inhibition (HI) test were compared for their ability to measure the primary serological response of chickens inoculated by the intranasal-intraocular (IN-IO) routes with Newcastle disease virus (NDV) and the secondary response after intratracheal (IT) challenge. In addition, these responses were compared with the temporal antibody response of chickens inoculated only once by the IT route. Both tests detected NDV-specific antibody by 7 days postinoculation (PI) in the IN-IO-inoculated group, while ELISA and the HI test detected antibody at 4 and 7 days, respectively, in the IT-inoculated group. Titers measured by each test were parallel in quantifying the antibody response, and titers rose anamnestically in response to secondary IT challenge at 21 days PI. ELISA titers remained high at 42 days PI, but the HI titers began to decline at this time. There was a good agreement (R = 0.94) between the results of the two tests throughout both primary and secondary responses. Conversely, there was little agreement between the results of the two tests after 21 days PI in the absence of secondary challenge. Antibody levels were higher when inoculation was by the primary IT route, and they persisted throughout the experiment (86 days). Ciliary activity served as a measure of tracheal immunity or infection of tracheal epithelium. It was reduced as early as 2 days PI and was nearly or completely absent by 5-6 days PI.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Intranasal↗

PubMedDate not supplied

A rapid method for preparing avian tracheal rings for organ culture.

A simple, rapid method for preparing rings from chicken tracheas is described. Using a polyacrylamide disc gel slicer, up to 100 uniform tracheal rings were obtained from two tracheas with a single cut and without injury to the ciliated tracheal epithelium. The responses of rings cut with a disc gel slicer and those cut conventionally with a scalpel blade were compared by virus titration, virus neutralization, and viability of uninfected 18-day-old-chick embryo rings over a nine-day incubation period. Rings cut with a disc gel slicer did not differ significantly from those cut conventionally with respect to virus titer, neutralization indices, or viability. A disc gel slicer expedites the preparation of functional rings and offers an alternative to the present method of cutting tracheal rings with a scalpel blade.

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PubMedDate not supplied

Detection and quantification of antibodies to infectious bronchitis virus by enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) for detecting and quantifying antibodies to infectious bronchitis virus (IBV) is described. Purified antigen, prepared on sucrose density gradients, was required to decrease the nonspecific background, and saline was found to be superior to bicarbonate buffer for coating the cuvettes with antigen. The sensitivity of the test in measuring antiserum titers could be altered greatly and linearly by adjusting the protein content of the antigen. The ELISA was able to detect an antibody response to IBV infection earlier than the virus-neutralization (VN) test. Antibody titers obtained by ELISA were considerably higher than those obtained by VN. Serotypes of IBV could not be differentiated with ELISA because of extensive antiserum cross-reactivity. The utility of ELISA in studies on IBV is discussed.

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PubMedDate not supplied

Comparison of ciliary activity and virus recovery from tracheas of chickens and humoral immunity after inoculation with serotypes of avian infectious bronchitis virus.

Cross-protection tests with homologous and heterologous serotypes of infectious bronchitis virus (IBV) were used to compare ciliary activity and virus recovery from tracheas of chickens. Validation of this technique included correlating the neutralization indices of antiserum obtained from some infected birds. Chickens were inoculated intratracheally with either the JMK or Connecticut (Conn) serotype of IBV. Three weeks later, infected and uninfected groups were challenged by the same route with homologous and heterologous virus. The JMK strain provided immunity against homologous challenge and the Conn strain, as indicated by good ciliary activity and lack of challenge virus recovery. The Conn strain provided only homologous protection, as ciliostasis occurred and virus was recovered after challenge with the JMK strain. In each case, antiserum to immunizing virus neutralized only the homologous virus. Controls were uniformly susceptible and lacked neutralizing antibody. A similar experiment with the Ark 99 serotype and a recent isolate (397) of IBV revealed complete cross-protection of the tracheas. Antiserum to each virus neutralized the homologous and heterologous virus in each case in reciprocal tests. The results indicate that these two viruses are closely related. The complete agreement between ciliary activity and virus isolation indicates that ciliary activity is a reliable, objective criterion upon which tracheal immunity can be judged in cross-protection tests.

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PubMedDate not supplied

Ciliary activity: a criterion for associating resistance to infectious bronchitis virus infection with ELISA antibody titer.

Vaccination and challenge experiments using infectious bronchitis virus (IBV) were conducted on groups of specific-pathogen-free chickens. Three weeks post-vaccination with one of the four IBV strains used, chickens were challenged with the homologous immunizing strain of IBV. Subsequently, the chickens were sacrificed, their tracheas were examined for ciliostasis, and the specific IBV antibody content of their sera was measured by enzyme-linked immunosorbent assay (ELISA). Results showed that protection was conferred by primary vaccination, as ciliostasis was not observed in tracheas from groups vaccinated and then challenged. No protection was observed in control groups that received only a challenge exposure, and the virus was readily recovered from their tracheas. Homologous protection was present in chickens that had ELISA titers as low as 624 and neutralization indices as low as 2.9, whereas susceptible controls had titers of less than 100 and less than 1.0, respectively.

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PubMedDate not supplied

Comparison of whole blood dried on filter paper and serum for measurement of the temporal antibody response to avian infectious bronchitis virus by enzyme-linked immunosorbent assay.

Two methods for collecting specimens for measuring sequential antibody activity of infectious bronchitis virus (IBV) were compared. Whole blood was collected on filter-paper strips, dried for 2 hr at 37 C, and then stored in plastic bags at 4 C or eluted overnight and tested immediately. Eluates of whole blood were paired with serum samples and tested for IBV antibody activity by enzyme-linked immunosorbent assay (ELISA) at four weekly intervals. Both sampling methods yielded ELISA antibody levels that were detectable at 7 days postinfection (PI), peaked at 21 days PI, and then began to decline by 28 days PI. The paired samples showed no significant difference (P less than 0.05) between ELISA titers at any time tested. Whole blood dried on filter paper could be stored sealed in plastic bags at 4 C for at least 2 weeks with no appreciable loss of antibody titers. Virus-neutralizing antibodies, measured in serum only, were not detectable until 14 days PI but then continued to rise through 28 days PI. It was concluded that eluates of whole blood dried on filter paper may be used as an alternative to sera in ELISA for measuring IBV antibodies.

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PubMedDate not supplied

Rapid serological profiling by enzyme-linked immunosorbent assay. III. Simultaneous measurements of antibody titers to infectious bronchitis, infectious bursal disease, and Newcastle disease viruses in a single serum dilution.

The present paper describes a method for measuring enzyme-linked immunosorbent assay (ELISA) antibody titers to infectious bronchitis (IB), infectious bursal disease (IBD), and Newcastle disease (ND) viruses from a single serum dilution using the same assay procedures and analyses. A regression line equation generated for predicting NDV ELISA antibody titers at a single serum dilution was successfully used to predict ELISA antibody titers to IB and IBD antigen preparations at the same test sera dilutions. Duplicate samples of 46 field and control sera were transferred simultaneously, with the aid of a replica plating device, from a reservoir plate to three different test plates, which were coated separately with IB, IBD, and ND antigens. After similar indirect ELISA parameters were conducted for each antigen, raw absorbance values from duplicate tests and controls were transmitted directly from an ELISA reader to a microcomputer, which subsequently processed average corrected absorbance values directly into individual ELISA antibody titer for each test antigen. The computer output listed individual field and control sample titers to each antigen, as well as graphing the relative ELISA titer distribution of the entire test group to each antigen. In a comparative study, test sera were evaluated for ELISA antibody titer to NDV, IBV, and IBDV by this method in three separate assays. Consistent titer values were obtained in all assays, as 96% of the 414 replicate titers evaluated varied less than twofold.

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PubMedDate not supplied

Rapid serological profiling by enzyme-linked immunosorbent assay. I. Measurement of antibody activity titer against Newcastle disease virus in a single serum dilution.

An enzyme-linked immunosorbent assay (ELISA) was developed to measure specific antibody activity in sera of chickens exposed to Newcastle disease virus (NDV). A near-linear relationship existed between the log of the corrected absorbance of antisera at a single working dilution and the corresponding observed serum titers as determined by a standard serial-dilution method. Regression analysis was used to construct a standard curve and extract an equation from this relationship. The equation was used to convert corrected absorbance readings of the single working dilution directly into predicted ELISA antibody activity titers. In a comparative study, a correlation (P less than 0.01) was found between ELISA and hemagglutination-inhibition (HI) antibody titers to NDV. ELISA titers were as much as 160 times greater than the HI titers. ELISA was also able to detect much lower levels of antibody activity than the HI test.

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PubMedDate not supplied

Rapid serological profiling by enzyme-linked immunosorbent assay. II. Comparison of computational methods for measuring antibody titer in a single serum dilution.

An enzyme-linked immunosorbent assay (ELISA) was used to measure specific antibody activity from a single serum dilution in sera of chickens exposed to Newcastle disease virus (NDV). Observed endpoint titers were used to formulate regression equations, and then absorbance data obtained at a single serum dilution were converted directly to antibody titer by three methods: a correction factor method, a subtraction method, and a double-regression method. Each method was evaluated for three criteria: the overall stability of between-test antibody titer for control sera, the linearity of the relationship of the absorbance values at a single working dilution to the observed antibody titers, and the method's accuracy in predicting titers. Although a nearly linear relationship was obtained for all treatment methods examined, the double-regression method provided the best reduction of between-test titer variation and also best predicted titers.

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PubMedDate not supplied

Epizootiology, pathology, and microbiology of an outbreak of urolithiasis in chickens.

An outbreak of urolithiasis that doubled the annual mortality rate of chickens in a large flock of table-egg-layers is described. Despite the presence of a large unilateral urolith and/or severe renal atrophy, the layers often maintained active egg production and apparent homeostasis until a small urolith blocked the ureteral flow from the contralateral kidney. This terminal episode appeared to produce acute obstructive renal failure, rapidly developing visceral gout (visceral urate deposition), uremia, and death. The atrophy observed appeared to be acquired and progressive. Histologic features in the kidneys were acute to chronic glomerulonephritis, interstitial nephritis, and pyelonephritis. Epizootiologic and microbiologic studies indicated that a combination of infectious and noninfectious mechanisms may have been involved. Causative roles for calcium-phosphate imbalance, infectious bronchitis (IB), Newcastle disease (ND), and adenovirus or reovirus infections could be neither excluded nor confirmed. Contributory factors may have been spray ND-IB and other vaccinations of 15-week-old ND-IB-susceptible pullets, water deprivation, shipping stress, Mycoplasma synoviae infection, immune complex disease, and mycotoxins.

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PubMedDate not supplied

Active cross-protection induced by a recombinant baculovirus expressing chimeric infectious bursal disease virus structural proteins.

The VP2 structural gene encoded in the large genomic segment A of the variant GLS strain of infectious bursal disease virus (IBDV) was modified to encode a neutralization epitope (B69), found only on classic strains of IBDV. A chimeric cDNA clone of the large segment A, encoding VP3, VP4, and the modified variant IBDV VP2 structural proteins, was expressed in a recombinant baculovirus. The chimeric protein expressed was assessed with a panel of neutralizing monoclonal antibodies (MAbs), and it contained not only all previously MAb-defined GLS variant strain epitopes but also the B69 neutralization epitope found on classic IBDV strains. Complete active protection was afforded to specific-pathogen-free chickens by a subunit chimeric vaccine against virulent challenge with the classic IM and STC strains, as well as against the variant E/Del and GLS IBDV strains. Compared with a previously tested recombinant subunit vaccine, which incorporated unmodified baculovirus-expressed large-segment A GLS proteins, the recombinant chimeric subunit vaccine resulted in markedly improved active cross-protection against classic IBDV challenge.

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