Genotyping of Chlamydophila psittaci using a new DNA microarray assay based on sequence analysis of ompA genes.
BACKGROUND
The currently used genotyping system for the avian zoonotic pathogen Chlamydophila (C.) psittaci has evolved from serology and is based on ompA sequence variations. It includes seven avian and two non-avian genotypes. Restriction enzyme cleavage of the amplified ompA gene and, less frequently, ompA sequencing are being used for examination, but, beside methodological limitations, an increasing number of recently tested strains could not be assigned to any established genotype.


RESULTS
Comprehensive analysis of all available ompA gene sequences has revealed a remarkable genetic diversity within the species C. psittaci, which is only partially covered by the present genotyping scheme. We suggest adjustments and extensions to the present scheme, which include the introduction of subgroups to the more heterogeneous genotypes A, E/B and D, as well as six provisional genotypes representing so far untypable strains. The findings of sequence analysis have been incorporated in the design of a new DNA microarray. The ArrayTubetrade mark microarray-based ompA genotyping assay has been shown to discriminate among established genotypes and identify so far untyped strains. Its high specificity, which allows detection of single-nucleotide polymorphisms, is due to the parallel approach consisting in the use of 35 hybridization probes derived from variable domains 2 and 4 of the ompA gene.


CONCLUSIONS
The traditional genotyping system does not adequately reflect the extent of intra-species heterogeneity in ompA sequences of C. psittaci. The newly developed DNA microarray-based assay represents a promising diagnostic tool for tracing epidemiological chains, exploring the dissemination of genotypes and identifying non-typical representatives of C. psittaci.
Sachse
Konrad
K
Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Insitute of Molecular Pathogenesis, Jena, Germany. konrad.sachse@fli.bund.de
Laroucau
Karine
K
Hotzel
Helmut
H
Schubert
Evelyn
E
Ehricht
Ralf
R
Slickers
Peter
P
D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D015373:Bacterial Typing Techniques / Q000379:methods*; D002691:Chlamydophila psittaci / Q000145:classification* / Q000235:genetics*; D016000:Cluster Analysis; D005838:Genotype; D046228:Microarray Analysis / Q000379:methods*; D017720:Molecular Epidemiology / Q000379:methods; D020411:Oligonucleotide Array Sequence Analysis; D011110:Polymorphism, Genetic; D009956:Psittacosis / Q000382:microbiology; D012680:Sensitivity and Specificity; D012689:Sequence Homology, Nucleic Acid
D001425:Bacterial Outer Membrane Proteins; C078167:OMPA outer membrane proteins