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DNAs from eight Chiamydia psittaci isolates (koala conjunctivitis, avian psittacosis, avian ornithosis, ovine abortion, ovine polyarthritis, sporadic bovine encephalomyelitis, and feline conjunctivitis) and one Chlamydia trachomatis isolate (lymphogranuloma venereum) were compared by restriction endonuclease and DNA probe analyses. Digestion with HindIll yielded a series of discrete fragments which allowed the differentiation of most isolates. A gene probe, pFEN207, which encodes the chlamydia-specific component of the Upopolysaccharide group antigen was used in Southern hybridizations. The probe was chlamydia specific and hybridized to a single BamHI fragment and multiple HindIH fragments in each isolate. The variation in size of the hybridizing fragments allowed easy differentiation of the isolates and may eventually lead to a meaningful subgrouping of the diverse group of disease agents presently included in the species C. psittaci.

A polymerase chain reaction (PCR)-based assay was developed for the detection of Eimeria acervulina. Primers were designed to amplify a fragment of the EASZ240/160 sporozoite antigen gene. The PCR assay detected as few as 10 E. acervulina oocysts in a mixed population containing a total of 10(6) oocysts. No nonspecific reaction was observed with any other species of avian Eimeria known to occur in Australia. PCR products from genomic DNA were 237 bp larger than predicted from previously reported cDNA sequences. Sequencing of the product revealed the presence of a probable intron. This work demonstrates the potential of PCR-based assays for identification and detection of avian Eimeria. Potential uses include identification of minor species present in mixed infections and quality control in the production of live vaccines.