A small nuclear ribonucleoprotein is required for splicing of adenoviral early RNA sequences.

Abstract
The size and structure of viral RNA species synthesized in nuclei (of human cervical carcinoma HeLa cells) isolated during the early phase of productive infection by adenovirus type 2 were examined by electrophoresis in denaturing polyacrylamide cells and the nuclease S1 assay. The major products of transcription in vitro of early regions 1 and 2 in the adenoviral genome are processed RNA molecules that appear to be correctly spliced in isolated nuclei. Splicing of adenoviral RNA molecules is inhibited when nuclei are preincubated with antibodies from systemic lupus erythematosus patients that immunoprecipitate small nuclear ribonucleoprotein particles. The specificity of these antibodies suggests that ribonucleoprotein particles containing U1 RNA are required for the splicing of the adenoviral RNA sequences which were examined.