Heart Transplant Research Today is a free monthly online journal that collates and summarizes the latest research about Heart Transplant, including details on risks, prognosis, procedure, surgery, organ donation.

Rat cytomegalovirus gene expression in cardiac allograft recipients is tissue specific and does not parallel the profiles detected in vitro.

Streblow DN, van Cleef KW, Kreklywich CN, Meyer C, Smith P, Defilippis V, Grey F, Früh K, Searles R, Bruggeman C, Vink C, Nelson JA, Orloff SL

Department of Molecular Microbiology and Immunology, The Vaccine and Gene Therapy Institute, Oregon Health and Science University, 505 SW 185th St., Beaverton, OR 97006, USA. streblow@ohsu.edu

Rat cytomegalovirus (RCMV) is a beta-herpesvirus with a 230-kbp genome containing over 167 open reading frames (ORFs). RCMV gene expression is tightly regulated in cultured cells, occurring in three distinct kinetic classes (immediate early, early, and late). However, the extent of viral-gene expression in vivo and its relationship to the in vitro expression are unknown. In this study, we used RCMV-specific DNA microarrays to investigate the viral transcriptional profiles in cultured, RCMV-infected endothelial cells, fibroblasts, and aortic smooth muscle cells and to compare these profiles to those found in tissues from RCMV-infected rat heart transplant recipients. In cultured cells, RCMV expresses approximately 95% of the known viral ORFs with few differences between cell types. By contrast, in vivo viral-gene expression in tissues from rat heart allograft recipients is highly restricted. In the tissues studied, a total of 80 viral genes expressing levels twice above background (5,000 to 10,000 copies per mug total RNA) were detected. In each tissue type, there were a number of genes expressed exclusively in that tissue. Although viral mRNA and genomic DNA levels were lower in the spleen than in submandibular glands, the number of individual viral genes expressed was higher in the spleen (60 versus 41). This finding suggests that the number of viral genes expressed is specific to a given tissue and is not dependent upon the viral load or viral mRNA levels. Our results demonstrate that the profiles, as well as the amplitude, of viral-gene expression are tissue specific and are dramatically different from those in infected cultured cells, indicating that RCMV gene expression in vitro does not reflect viral-gene expression in vivo.

Published 29 March 2007 in J Virol, 81(8): 3816-26.
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