An Epstein-Barr Virus-Determined Nuclear Antigen Encoded by a Region within the EcoRI a Fragment of the Viral Genome
Large Epstein-Barr virus (EBV) DNA restriction fragments corresponding to regions transcribed in transformed, proliferating cells were cloned into a cosmid derivative of the dominant-acting selection vector pSV2-gpt. Recombinant vectors carrying the EcoRI A fragment of EBV DNA were modified in the region corresponding to the deletion of the virion DNA in the non-transforming viral substrain P3HR-1, to create a series of recombinants lacking parts of this region. The recombinant vectors were introduced into 3T3 mouse fibroblasts under selective conditions, and resistant clones shown to contain EBV DNA sequences were analysed for the expression of EBV-related antigens detectable by direct, indirect, and anticomplement immunofluorescence techniques. Cells that contained the BamHI K fragment expressed a nuclear antigen as expected. It is demonstrated here that cells transfected with recombinant vectors containing the major part of the EcoRI A fragment also express a nuclear antigen detectable with certain anti-EBNA-positive human sera in anticomplement immunofluorescence tests. This antigen is not detected in cells transfected with EcoRI A derived vectors where the BamHI H fragment has been deleted, nor in cells transformed with vectors carrying the BamHI H fragment alone. Direct and indirect immunofluorescence did not reveal the presence of antigens associated with productive infection in any of the EBV DNA transfected fibroblast clones.
In this study we address the question whether EBV genome regions transcribed in transformed, non-virusproducing cells, other than the BamHI K fragment region, are also involved in the induction of EBV-associated nuclear antigens. EBV DNA fragments representing these regions were introduced into 3T3 mouse fibroblast using transducing selectable vectors. Cells transformed stably with EBV DNA were selected and characterised with regard to the expression of EBV-related antigens as detected by immuno-fluorescence techniques. We show here, that cells transfected with recombinant vectors containing the major part of the EcoRI A fragment of EBV DNA express a nuclear antigen that reacts with certain anti-EBNA-positive human sera in ACIF tests. This antigen is not present in cells transfected with EcoRI A carrying vectors where the BamHI H fragment has been delected.
KeywordsNuclear Antigen ACIF Test Mycophenolic Acid Recombinant Vector Early Antigen
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