Virus-associated RNAs (VA-I and VA-II): An efficient target for the detection of adenovirus infections by in situ hybridization

The identification of adenovirus in tissue can be difficult. In situ hybridization for adenovirus nucleic acids may aid in the demonstration of adenovirus infections. To develop a probe against adenovirus, a 978 bp fragment of DNA containing the VA-I, VA-II, and a portion of the L-I regions of the adenovirus type 2 genome was cloned into the SK+ vector. These regions were selected because they are generally conserved among adenoviruses and are abundantly transcribed during the lytic cycle. Sense and antisense tritium or Digoxigenin-labeled riboprobes were generated using in vitro transcription and applied to formalin-fixed paraffin-embedded sections of HeLa cells infected with adenovirus type 2. Extensive in situ hybridization of the antisense riboprobe tu HeLa cells with cytopathic changes was found. The number of cells to which the probe hybridized decreased proportionately with dilution of infected with noninfected cells. The control sense riboprobe showed only scattered breakthrough hybridization and in these cells hybridization was mainly located in the nucleus. Northern blot analysis of RNA from infected HeLa cells confirmed the in situ hybridization results. No hybridization was detected when cultured cells infected with herpes simplex virus, Epstein-Barr virus, cytomegalovirus, or human immunodeficiency virus were examined. Specific hybridization was detected in tissues obtained at autopsy from four patients with culture proven adenovirus infection. These observations suggest that this probe is useful in the diagnosis of adenovirus in formalin-fixed paraffin-embedded material.