Direct Sandwich Enzyme-linked Immunosorbent Assay Research Articles

Survey of Spring Oats for Barley Yellow Dwarf Viruses in Illinois

During the spring of 1987, 1,215 samples of spring oats (Avena sativa L.) were collected in Madison, Champaign, Woodford, Warren, and DeKalb counties, Illinois. At each site on each of three sampling dates, 45 samples were collected (regardless of symptoms) in a W pattern in I ha and tested for the PAY, MAV, RPV, and RMV serotypes of barley yellow dwarf virus (BYDV) by direct doubleantibody sandwich enzyme-linked immunosorbent assay (ELISA). RMV was not detected at any location. PAY and RPV were detected at all locations, as early as 17 April in Champaign County. The incidences of P A V and RPV from all plants sampled ranged from 2 to 64% and from 2 to 88%, respectively. Highest incidences of both strains were in May samples [rom Woodford County. MAV was detected in lower incidences (2-16%) only in samples from the central region of the state (Champaign, Woodford, and Warren counties). The presence of MA V serotypes was confirmed in triple-antibody sandwich ELISA with the MA V -specific MAFF2 monoclonal antibody from L. Torrance. In the last previous survey for BYDV in Illinois during 1967-1968 (1), about 75% of the isolates were PAY and about 20% were RPV; single isolates of RMV and MAV were found. Twenty years later, 55% were PAY, 39% were RPV, and 6% were MAV.

Sensitive detection of two plant viruses by enzyme-amplified elisa

Enzyme-amplified ELISA (enzyme-linked immunosorbent assay) increased the sensitivity of detection of citrus tristeza virus and papaya ringspot virus in plant sap by 25- and 125-fold, respectively, compared with direct double antibody sandwich ELISA. The advantages of the new substrate system for the detection of low concentrations of viruses in plants are discussed.

Haemophilus influenzae type b capsular polysaccharide detection and measurement by an enzyme-linked immunosorbent assay (ELISA)

A direct sandwich enzyme-linked immunosorbent assay (ELISA) was developed to detect Haemophilus influenzae type b capsular antigen. Using polystyrene as the solid phase and peroxidase-labelled rabbit antibody the assay detected the antigen in concentrations of 0.1 ng/ml. Linearity was achieved within the range of 1ng to 10 microgram/ml. Subtle measurements of Haemophilus influenzae type b capsular antigen in body fluids are possible through ELISA which is superior to counterimmunoelectrophoresis and latex-particle agglutination in this respect. ELISA should facilitate investigations concerning PRP pathogenic effects in experimental Hib infection as well as in human Hib disease.