An enzyme linked immunoassay for estimation of antibodies to Newcastle disease virus strains

The sensitivity of enzyme linked immunoassay (ELISA) was compared to that of haemagglutination inhibition (HI) test in detection of humoral antibodies in birds vaccinated with Newcastle disease virus (NDV). The highest antibody titre at day 21 post-vaccination as detected by ELISA in the sera of vaccinated birds was 2560 by all strains in contrast to the HI titres of 640 to 1280. The antibody titre was higher in all pre- and post-vaccination sera as determined by ELISA than detected by HI test.

Ocular pathogenesis of Newcastle disease virus in rabbits and monkeys

Studies on the ocular pathogenesis of Newcastle disease virus (NDV) in rabbits and monkeys revealed that conjunctivitis can only be produced by the virus when conjunctival epithelium is traumatized; multiple instillations of large doses of virus over the intact conjunctiva failed to do so. The presence of serum HI antibodies showed no correlation with the clinical form of the disease in rabbits. However, in monkeys, the disease showed a uniform pattern of immune response irrespective of the strain of the virus. Monkeys may be useful for further studies.

Comparative evaluation of the enzyme immunoassay and the immunofluorescence test for the detection of chlamydial group antibodies in human sera

The usefulness of an enzyme-linked immunosorbent assay (ELISA) in detecting chlamydial group antibodies in human sera was evaluated by comparing the results with a standard micro-immunofluorescence test (micro-IF). Of the 176 samples tested, 94.9% sera gave concordant results, 23.9% being positive and 71% negative by both the tests. ELISA detected specific antibodies in 33.3% and 13.5% sera from poultry associated and unassociated individuals respectively while corresponding figures by IF test were 36.3% and 16.2% (p less than 0.01). The IF and ELISA titres of five immune serum samples from monkeys when compared with conventional complement fixation (CF) test were found to be consistently higher. Though the two tests were found to be parallel in sensitivity and specificity (r = 0.94), IF had a marginal superiority over ELISA, while the latter could be performed more easily and read objectively.

Comparison of four serological methods for detecting antibodies to Chlamydia trachomatis

The ability of four serological methods (enzyme-linked immunosorbent assay, single radial haemolysis, micro-immunofluorescence and complement fixation) to detect chlamydial antibodies was compared. Antigen was prepared from Chlamydia trachomatis serotype E. Sixty-two sera known to be positive and 12 negative reference sera were screened. The four tests yielded 71.6% (53/74) concordant results (Chi-square = 14.57, p less than 0.01). Samples giving discordant results had only low levels of antibodies. Analysis of results showed a strong correlation between enzyme-linked immunosorbent assay and immunofluorescence (r = 0.98), and complement fixation and single radial haemolysis (r = 0.75). Antibodies were detected in 97% of the 62 positive sera by immunofluorescence and in 91% by enzyme-linked immunosorbent assay, whereas the results for complement fixation and single radial haemolysis were only 69.3% and 70.9% respectively. Extrapolation of the regression curve to the abscissae indicated a marginal superiority of immunofluorescence over enzyme-linked immunosorbent assay, although the reading of the results of the former test was more cumbersome. Good linearity was obtained between haemolytic zone diameter and reciprocal serum dilution in single radial haemolysis. Immunofluorescence was found to be the most sensitive and complement fixation the least sensitive of the four tests.

Subtyping of foot-and-mouth disease virus by the micro-enzyme-labelled immunosorbent assay (MICROELISA)

The micro-enzyme-labelled immunosorbent assay (MICROELISA) was used successfully for the subtyping of foot-and-mouth disease (FMD) virus strains recovered from field outbreaks. The rabbit anti-guinea pig globulin-peroxidase conjugate employed in the indirect MICROELISA has the advantage of being used with any of the seven types of FMD virus.

Comparison of enzyme-linked immunosorbent assay and haemagglutination inhibition test for the detection of Newcastle disease virus antibodies in human sera

A comparison of haemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA) techniques for the detection of antibodies against Newcastle disease virus in sera from persons working in poultry farms and veterinary vaccine institutes and from the general population revealed that 22% more sera were positive by ELISA compared to HI. No samples were negative by ELISA but positive by HI. While HI titres of positive sera were found in the range 8-64, ELISA titres were between 16 and 512. It was interesting that though 78% sera had concordant results by the two tests, titres obtained by ELISA were nearly six times higher than those by HI.

A micro-enzyme-lavelled immunosorbent assay (MICORELISA) for the detection of foot-and-mouth disease virus antigen and antibody

The indirect technique of a micro-enzyme-labelled immunosorbent assay (MICROELISA) was standardized and found efficient in detecting the foot-and-mouth disease virus antigen in cell culture fluids, mice carcases and cattle tongue epithelium as well as the antibody titre of sera.

Yellow nail syndrome associated with mental retardation in two siblings

Two siblings with yellow nail syndrome and mental retardation are described. In addition to nail changes, the younger brother was found to have congenital lymphoedema and idiopathic pleural effusion, and the elder brother, lymphoedema praecox. They had in common a history of respiratory tract infections. Their intelligence quotient as measured by the Suzuki-Binet tests was 30% and 70%, respectively.

Cultivation of foot and mouth disease virus in bovine leukocyte cultures for use in the complement fixation test

Bovine leukocyte cultures achieved good growth after 72 hours of cultivation. Foot-and mouth disease (FMD) virus type 0 multiplied in such cultures to a titre of 10(6) TCID50/0.1 ml. The cell culture-grown virus was found to be suitable for the complement fixation test (CFT) after purification and concentration with calcium phosphate.