Diagnosis of ovine enzootic abortion, using a competitive ELISA based on monoclonal antibodies against variable segments 1 and 2 of the major outer membrane protein of Chlamydia psittaci serotype 1.
OBJECTIVE
To develop and evaluate a competitive ELISA (cELISA) specific for detection of antibodies to abortion strains of Chlamydia psittaci and C pecorum that is based on monoclonal antibodies against the 2 segments. PROCEDURA: Monoclonal antibodies were screened for binding to ELISA plates coated with elementary bodies, and were selected on the basis of positive competition with experimentally produced sera against C psittaci and lack of competition with anti-C pecorum sera. The cELISA was evaluated with field sera, and the results were compared with those obtained by complement-fixation testing and by an ELISA containing solubilized outer membrane complexes (A-ELISA).


RESULTS
The cELISA detected 9 of 10 C psittaci-infected flocks (57/125 sera, 45.6%), and in 6 of 10 flocks (27.3% of the sera), it specified correctly the infecting chlamydial species. Regarding test sensitivity, the complement-fixation test detected 6 of 10 test-positive (19.2% of the sera) flocks, whereas 7 of 10 test-positive (48.8% of the sera) flocks were detected by use of the A-ELISA. The specificity of the test was satisfactory (100%), compared with the A-ELISA (72.2%).


CONCLUSIONS
The new cELISA is a sensitive and specific assay for antibodies against C psittaci abortion strains. It is rapid and easy to perform and does not require serum dilutions. The new cELISA is, therefore, suitable as a routine test for chlamydial diagnosis and seroepidemiologic studies.
Salti-Montesanto
V
V
Department of Biotechnology, Hellenic Pasteur Institute, Athens, Greece.
Tsoli
E
E
Papavassiliou
P
P
Psarrou
E
E
Markey
B K
BK
Jones
G E
GE
Vretou
E
E
D000034:Abortion, Veterinary / Q000382:microbiology*; D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D002691:Chlamydophila psittaci / Q000276:immunology / Q000302:isolation & purification*; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000032:analysis; D005260:Female; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology; D011247:Pregnancy; D009956:Psittacosis / Q000175:diagnosis / Q000662:veterinary*; D012680:Sensitivity and Specificity; D012756:Sheep; D012757:Sheep Diseases
D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D001425:Bacterial Outer Membrane Proteins; D000939:Epitopes; D010446:Peptide Fragments