OBJECTIVEChlamydia psittaci is an avian respiratory pathogen and zoonotic agent. The wide prevalence of C. psittaci poses a threat to the poultry industry and its employees. However, few commercial kits are available for detecting avian antibodies excluding the in-house ELISA kit. In this study, we developed a novel ELISA kit for detecting antibodies against C. psittaci based on the N-terminal fragment of polymorphic outer membrane protein D (PmpD-N) as the coating antigen.

METHODSThe antigen concentrations, primary antibody, and cut-off value were determined and optimized. The ELISA, designated PmpD-N ELISA, was assessed for sensitivity, specificity, and concordance using sera samples from 48 experimentally infected and 168 uninfected SPF chickens.

RESULTSThe sensitivity and specificity of PmpD-N ELISA were 97.9%, 100%, respectively, while the concordance was 98.1% as compared to that of MOMP-ELISA. No cross-reaction with positive sera for other avian pathogens was found. Using PmpD-N ELISA, 799/836 clinical samples were positive, including 93.0% and 98.1% positivity in layers and broilers, respectively.

CONCLUSIONThese data indicate that indirect ELISA with PmpD-N as the antigen candidate is a promising approach for the surveillance of C. psittaci infection.

Animals ; Bacterial Proteins ; analysis ; Chickens ; Chlamydophila psittaci ; genetics ; immunology ; isolation & purification ; Enzyme-Linked Immunosorbent Assay ; veterinary ; Membrane Proteins ; analysis ; Poultry Diseases ; diagnosis ; microbiology ; Psittacosis ; diagnosis ; microbiology ; veterinary ; Sensitivity and Specificity

Salmonellosis in poultry of Korea is a significant health problem, which causes substantial economic losses. The most common causative agents of chicken salmonellosis ar S. gallinarum and S. pullorum. Traditional methods used to detect Salmoenella spp. In chicken are tedious, time consuming and confer little guarantee of sensitivity and species specificity. Therefore, a rapid and sensitive method for the differentiation of Salmonella serogroup D was assessed. We first amplified the rfbS genes by PCR and characterized the amplified product by nucleotide sequence analysis. The homology of nucleotide sequence was 99.7% between S. gallinarum and S. pullorum rfbS genes. Further comparisons of the sequences of S. gallinarum, S. gallinarum fied strain, S. pullorum and S. typhi(GenBank Accession No.M29682) showed a homology of 98.3%. The predicted amino acid sequence homology was 97.1%, 97.1% and 97.5%, respectively. Based on this comparison of these nucleotide sequences, we found unique restriction enzyme sites within the rfbS genes of S. gallinarum and S. pullorum. Thus, the PCR products could be further digested with restriction enzymes TfiI and PleI for use in a restriction fragment length polymorphism (RELP) technique. This method can be applied in the differential diagnosis between S. gallinarum and S. pullorum.
Animals ; Base Sequence ; *Chickens ; Diagnosis, Differential ; Polymerase Chain Reaction/veterinary ; Polymorphism, Restriction Fragment Length ; Poultry Diseases/*diagnosis/microbiology ; Restriction Mapping/veterinary ; Salmonella/*classification/genetics/isolation&purification ; Salmonella Infections, Animal/*diagnosis/microbiology ; Sensitivity and Specificity ; Sequence Homology, Amino Acid ; Sequence Homology, Nucleic Acid ; Species Specificity