Submitted to: Veterinary Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/1998
Publication Date: N/A
Interpretive Summary: Methods for detecting and identifying the specific location of chlamydiae in infected tissues are needed for pathogenesis studies and diagnoses. Nonradioactive digoxigenin-labeled probes were developed that could be used to hybridize to specific chlamydiae RNA. The probes were used to detect and localize swine Chlamydia trachomatis strains in formalin-fixed, paraffin-embedded tissue specimens. The morphology of the infected cells were preserved so that the type of cells could be determined. The technique will benefit research in that it can be used to locate and identify the exact cells infected by chlamydiae. It will also provide an additional method for the diagnosis of chlamydiae from tissue specimens.
Technical Abstract: Gnotobiotic piglets were inoculated intralaryngeally with swine Chlamydia trachomatis strains R33 or orally with Swine C. trachomatis Strain R27. Archived formalin-fixed, paraffin-embedded tissues from piglets euthanatized 4-7 days postinoculation were examined by in situ hybridization for C. trachomatis nucleic acid using a nonradioactive digoxigenin-labeled DNA probes that targeted specific ribosomal RNA or omp1 epithelial cells, bronchiolar epithelial cells, pneumocytes, alveolar and interstitial macrophages, and jejunal and ileal enterocytes. Chlamydia-infected cells had a strong signal that was confined to the intracytoplasmic inclusions. Positive hybridization signals were not detected in tissue sections from an uninfected control piglet or in C. psittaci-infected sheep placenta. The morphology of host cells were preserved despite the relatively high temperature required in parts of the incubation procedure. The data indicate that in situ hybridization can be used to detect swine C. trachomatis in formalin-fixed, paraffin-embedded tissue specimens.