Core and E antigen synthesis in rodent cells transformed with hepatitis B virus DNA is associated with greater than genome length viral messenger RNAs

Abstract

The viral RNA sequences in a number of rodent cell lines which contain integrated hepatitis B virus DNA were examined. In one of the cell lines, which produces the hepatitis B virus surface, core and e antigens, there are four polyadenylated, cytoplasmic RNA species, estimated to be 4425, 3968, 2435 and 1054 nucleotides in length, which hybridize with hepatitis B virus DNA. All four were shown to be transcripts of the coding strand of the virus genome and the regions contained in each RNA molecule were determined by hybridization with probes from different parts of the genome. The two largest RNAs hybridized with probes from all parts of the genome. The 2.4 x 10(3) nucleotide RNA, which is the same size as the previously identified surface antigen messenger RNA, hybridized with probes covering the surface antigen gene but not with probes corresponding to the core antigen gene. It also hybridized with a probe mapping upstream of a sequence previously suggested to be its promoter. The 10(3) nucleotide RNA was mapped to the X gene region and thus provides evidence that this open translational reading frame does encode a product. This RNA is possibly 3' coterminal with the surface antigen mRNA. The two largest RNAs, which are greater than the length of the hepatitis B virus genome, are present in three independent cell lines which produce core antigen and e antigen in addition to surface antigen, but absent from two cell lines which produce only surface antigen. Therefore, it appears that these RNAs are entirely hepatitis B virus-specified, rather than being co-transcripts with cellular sequences, and also that one of them encodes the core and e antigen produced by these cells.