Characterization of the murine cytomegalovirus m136 gene.
The 230-kbp murine cytomegalovirus (MCMV) genome is predicted to encode 182 open reading frames (orfs). One gene whose functional role is not known is encoded by the 762-bp m136 orf. Sequence analysis of rat cytomegalovirus (RCMV) strains Maastricht and English revealed homologous orfs, pr136, and ORF HJ4, respectively. Conservation of these orfs suggested that m136 and the RCMV homologs might play a role during virus replication. Expression of an epitope tagged form of m136 (m136-V5) yielded a polypeptide of 34 kDa that localized to the perinuclear region of transfected mouse 3T3 fibroblasts. Three independently generated MCMV m136 mutants were isolated and characterized. Mutations were introduced into the m136 orf by inserting either a beta-glucuronidase (m136-beta-gluc) or a guanosine phosphoribosyl transferase (m136-gpt) expression cassette into a unique BglII site, or by inserting a gpt cassette into a deleted region (Deltam136) of m136. No differences were observed in viral yield, plaque size, and plaque morphology between the parental strain and any of the m136 mutant viruses. In vivo analysis using a SCID mouse virulence model showed a consistently measurable attenuated phenotype for all three m136 mutants. The results showed that although the m136 gene was not essential for replication in vitro or in vivo, an intact m136 gene was necessary to yield wild type virulence during infection of the host.
Visalli
Robert J
RJ
Department of Biology, Indiana University Purdue University Fort Wayne, 2101 E. Coliseum Blvd., Fort Wayne, IN 46805, USA. visallir@ipfw.edu
Nicolosi
Denise M
DM
Irven
Karen
K
Khan
Tamseel
T
Visalli
Melissa A
MA
D000818:Animals; D004279:DNA, Viral; D005814:Genes, Viral; D016679:Genome, Viral; D051379:Mice; D016513:Mice, SCID; D018146:Muromegalovirus / Q000235:genetics / Q000502:physiology*; D016366:Open Reading Frames; D017422:Sequence Analysis, DNA; D014407:Tumor Cells, Cultured; D014764:Viral Proteins / Q000235:genetics / Q000502:physiology*; D014774:Virulence / Q000235:genetics
D004279:DNA, Viral; D014764:Viral Proteins