In situ hybridization (ISH) is a technique that uses labeled DNA or RNA probes to detect molecules with sufficiently similar, complementary sequences within tissue sections. At the MSU VDL, ISH is primarily used to identify and localize infectious agents within lesions, but it may also be used to localize genes and their transcripts. In essence, any nucleic acid sequence can be specifically detected by the use of such probes. We also custom generate probes for research purposes.

Use of ISH in the Laboratory

We use digoxigenin labeled oligonucleotide probes, which are stable, easy to synthesize, and only hybridize to specific target nucleic acid. We primarily use probes to detect viruses, rickettsia, and fungi. Whereas most of our probes are species-specific, some are more generic. By first screening tissues with a generic probe, we can search for a wider range of agents and use species-specific probes at a later stage to speciate the agent of interest. ISH may also be used to localize mRNA and to determine expression levels of specific transcripts such as oncogenes.

Currently available probes include the following targeted at:

  • Aleutian disease virus
  • Blastomyces dermatitidis
  • Canine herpesvirus
  • Canine herpesvirus
  • Coccidioides immitis
  • Eastern equine encephalitis virus
  • Feline herpesvirus
  • Filamentous fungal organisms
  • Generic Chlamydophila and Chlamydophila psittaci
  • Generic Leishmania and Leishmania infantum
  • Generic papillomavirus (can also detect papillomavirus in equine sarcoids or feline squamous proliferative lesions)
  • PorcineDog circovirus
  • Viral hemorrhagic disease virus
  • West Nile virus

Benefits to Clients

In general, ISH is regarded as a time-consuming, labor intensive and capricious method. With our state-of-the-art automated technology we can complete the entire protocol in one day, producing highly consistent results. The test can be performed on routine formalin-fixed paraffin-embedded material. With the use of ISH, we are independent of antibodies that may cross-react and we can target any infectious agent or gene of known sequence data. We can likewise develop and validate an assay that meets your specific needs if you provide us with the sequence of a specific infectious agent or gene of interest and with proper control tissues.