Twelve monoclonal antibodies (MAbs) against the widely used herbicide 2,4-D were produced by hybridomas from two fusions of murine myeloma cells and spleen cells isolated from BALB/c mice immunized with hapten conjugated via the carboxyl group to thyroglobulin. To evaluate the sensitivity and selectivity of MAbs, competitive indirect ELISA was used. MAb E2/G2 exhibited the highest sensitivity toward 2,4-D (IC50 = 0.8 ng/mL) and a favorable selectivity toward 18 structurally related substances. Besides the expected high cross-reactivity with methyl ester 2,4-D (104.8 %), cross-reactivity with MCPA (13.8%) and with 2,4,5-T (9.5%) was found. Cross-reactivity with other structural analogs did not exceed 2.7%. Optimization studies showed that in competitive ELISAs for 2,4-D coating conjugates with hapten densities of 2.3 and 3.3 mol of 2,4-D/mol of BSA were more sensitive than conjugates with hapten densities of 15.9 and 26.5 mol of 2,4-D/mol of BSA. The best dose-response curves presented in this study were almost linear in the concentration range 0.2-10 ng/mL. 2,4-Dichlorophenoxyacetic acid (2,4-D) is a broadly used herbicide for controlling weeds which could potentially contaminate groundwater and the drinking water supply. The allowable limits for pesticide residues in drinking water are becoming lower and lower. In European Community (EC) countries, the maximum admissible concentration is 0.1 ng/mL of any one substance and 0.5 ng/mL for a sum of pesticides, including metabolites (Wittmann and Hock, 1991).Conventional methods of quantitation of polar phenoxyalkanoic acids include liquid-liquid extraction, acidbasic partitioning, chemical derivatization, and purification. This procedure is time-consuming, it involves toxic solvents and reagents, and the results are often inconsistent (Loconto, 1991). Therefore, quick, easy, and economical

Monoclonal antibodies to porcine epidemic diarrhoea virus (PEDV) membrane protein M were prepared and used for the comparative assessment of three blocking ELISA variants to detect PEDV. The competitive blocking ELISA (CB-ELISA) format showed the highest sensitivity, allowing detection of 10(2.5) plaque-forming units of PEDV/ml in culture medium. Its specificity was verified by inclusion of control samples containing transmissible gastroenteritis virus (TGEV) and rotavirus A in each analysis. Eighty porcine field samples of faeces obtained from 38 herds affected with diarrhoea were examined, and PEDV was found in 15 (19%) samples from 6 (16%) herds. The suitability of the CB-ELISA for the screening herds in epizootiologic situations is discussed.

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Hybridomas producing monoclonal antibodies (MAbs) to rabbit haemorrhagic disease virus (RHDV) were prepared. Using Western blot (WB) analysis, the MAbs obtained were divided into two groups, one reacting with the major structural proteins of Mr 61K and 38K, and the other giving negative reactions. Both groups of MAbs, however, reacted specifically with RHDV in ELISA and by immunoperoxidase (IP) and immunofluorescence (IF) tests with infected ceils. As demonstrated by WB using RHDV-specific MAbs and a MAb to feline calicivirus (FCV) strain F9, the major structural (capsid) proteins of RHDV and FCV have very similar sizes (Mr 61K and 38K compared to 62K to 64K and 40K respectively). No cross-reactions of MAbs with proteins of the other virus were observed in WB analysis, ELISA, IP tests or IF. The high specificity and sensitivity of RHDV-specific MAbs make them suitable for the routine IP and IF diagnosis of RHDV in liver cells of rabbits dying after natural or experimental infections.

Development of direct competitive enzyme-linked immunoadsorbent assays (ELISAs) based on polyclonal and monoclonal antibodies raised against 4-n-alkylphenol hapten mimics is described. A strong tendency to recognize 4-nonylphenol (NP) and 4-octylphenol (OP) as a total analyte amount was indicated by cross-reactivity pattern established for two polyclonal antibodies. These antibodies were employed for development of class-selective assays exhibiting IC(50) values around 40 microg.L(-1) for technical 4-NP. Specificity of the monoclonal antibody 4H6 and additional two polyclonal antibodies allowed sensitive detection of linear long-chain forms of 4-n-alkylphenols (4-n-AP). The assays incorporating these antibodies offer a potential for detecting the minor fraction of NP/OP isomer spectrum having IC(50) = 11.5 microg.L(-1) for 4-n-NP. No cross-reactivity interference was indicated for linear alkylbenzene sulfonates and phenolic compounds. To interpret the measured data in terms of analytical equivalents, a reliable relationship between the assay responses and AP content of contaminated samples should be verified and validated.