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Publisher Summary Retroviruses employ a unique replication strategy. One of the features of their replication is the integration of a DNA copy of the RNA genome (provirus) into the host cell chromosomes. The integrated viral DNA copy is then used as a template by the host cell RNA polymerase to synthesize transcripts identical to the genomic RNA. In contrast to the primary transcripts of most cellular genes, which undergo complete splicing, only about 50% of the molecules of the retroviral RNA pool are spliced and the remainder are unspliced. Because unspliced RNA containing the entire viral genome is required for packaging into progeny virus particles and spliced RNA is required for the expression of some viral genes (e.g., the viral envelope gene), the exclusion of a fraction of the RNA from splicing and the transport of both spliced and unspliced RNA to the cytoplasm are obligatory steps in the life cycle of retroviruses. Thus, the processing of retrovirus RNA has interesting and unusual features. |
