Comparison of the dot-immunobinding assay with the complement fixation test for the detection of Brucella antibodies in sheep

Detection of Campylobacter antibodies in sheep sera by a Dot-ELISA using acid extracts from c. fetus ssp. fetus and c. jejuni strains and comparison with a complement fixation test

In this study, a dot-enzyme-linked immunosorbent assay (Dot-ELISA) was evaluated in comparison with a complement fixation test (CFT) for the detection of Campylobacter antibodies in sheep sera. Acid glycine extracts (AGE) of both Campylobacter fetus ssp. fetus and Campylobacter jejuni strains that had been isolated from the gall-bladder of slaughtered sheep was used as antigen in both tests. A total of 153 sheep sera from aborted (74) and slaughtered (79) sheep were examined by both Dot-ELISA and CFT. Twenty-two sera showed anti-complementary activity were not suitable for CFT. Of the 22 sera showing anti-complementary activity, two sera were found to be positive in Dot-ELISA. Eighty-eight (67.2%) of the remaining 131 sera were negative by both Dot-ELISA and CFT using AGE of both Campylobacter strains whereas 43 sera (32.8%) gave different reaction patterns in Dot-ELISA and CFT with the extracts of both Campylobacter strains. Twelve sera were positive by both tests using AGE of C. fetus ssp. fetus but CFT failed to detect antibodies in nine of these sera when AGE of C. jejuni was used. Twelve sera were positive by both tests only when AGE of C. fetus ssp. fetus was used. Eleven sera were positive only by CFT. Seven of these reacted only with the AGE of C. fetus ssp. fetus and four sera were positive by using AGE of both Campylobacter strains. The remaining eight sera were found to be positive only by dot-immunobinding assay either with the AGE of both Campylobacter strains or with the AGE of one of the Campylobacter strains. It is concluded that Dot-ELISA using AGE from C. fetus ssp. fetus could be employed for the detection of Campylobacter antibodies in sheep sera and the additional use of AGE from C. jejuni as antigen appeared not to be profitable for this purpose.

Comparative evaluation of a field-based dot-ELISA kit with three other serological tests for the detection of Brucella antibodies in goats

A dot-ELISA (d-ELISA) test was evaluated and compared with the serum agglutination test (SAT), micro-complement fixation test (CFT) and a plate-ELISA (p-ELISA) for field use in screening herds of goats against brucellosis. During the standardization of the dot-ELISA kit on 1732 caprine serum samples, 1571 samples out of 1666 were found to be negative in d-ELISA, SAT and micro-CFT, while 59 were positive in different combinations. Of a further 66 serum samples, 34 were negative and 31 were positive in different combinations in d-ELISA, SAT, micro-CFT and p-ELISA. A total of 1584 goats belonging to different herds were then screened for brucellosis. Of the 694 serum samples screened in the first batch using d-ELISA, a positive reaction was observed in 26 cases. Further screening of these cases revealed 13 and 21 goats as positive reactors in SAT and CFT, respectively. In a second batch of 890 goats there were 109 positive reactors in d-ELISA. Among these 109 goats, 34, 40 and 80 goats were positive reactors in SAT, CFT and p-ELISA, respectively. The results of d-ELISA correlated well with those of p-ELISA. Dot-ELISA was found to be a more suitable and rapid test for screening large numbers of goats in the field.

Indirect haemagglutination test for the serodiagnosis of brucellosis using stabilised sheep red blood cells

Sheep red blood cells (SRBCs) stabilised with formaldehyde, glutaraldehyde, pyruvic aldehyde and double aldehyde were evaluated, in the indirect haemagglutination (IHA) test, for their suitability for the serodiagnosis of brucellosis in bovines. Serum samples from 23 standard tube agglutination test (STAT)-positive and 12 clinically suspected but STAT-negative cows were titrated by the IHA test. Double aldehyde and glutaraldehyde-stabilised SRBCs were found to be more sensitive in the IHA than the formaldehyde or pyruvic aldehyde-stabilised SRBCs. Double aldehyde and glutaraldehyde treatments enabled the IHA to clearly differentiate between the normal and the diseased cows. Double aldehyde-stabilised cells have an edge over the glutaraldehyde-stabilised SRBCs because the former treatment makes the SRBCs readily available for antigen coating without tannic acid activation.