Studies on Some Early Polypeptides Encoded by Adenovirus Type 5

Abstract

<p>In recent years a substantial amount of research work has concentrated on defining the polypeptides encoded by the early regions of adenovirus. However, large gaps remain in the knowledge of the identities, relationships and viral DNA sequences encoding the various early polypeptides. This study adds to the information on the early antigens of Ad5 and provides a basis upon which further studies can build.</p> <p>A series of polypeptides present in cells early after infection by Ad5 have been studied. They have been immunoprecipatated with five different antisera from extracts of infected cells and from cell-free extracts following the translation of viral mRNA. The antigens have been divided into families of related products by peptide mapping techniques. Partial amino terminal amino acid sequences have been obtained for five early polypeptides which has allowed these products to be associated with specific open reading frames in the Ad5 genome.</p> <p>The results show that: Region E1A encodes two families of antigens which are closely related but are not identical [52K(12) and 48K(12) from the 135 mRNA; 50K(12) and 44K(12) from the 125 mRNA] and all but the 44K(12) (which was not examined) are synthesized from one translation initiation site, located at 1.43 mu in the Ad5 genome. Early region IB encodes a 19K polypeptide which is not related to a second family of antigens from the same region (58K, 53K, 29K and 18K). The 19K polypeptide is produced from an initiation codon located at 4.68 mu in the Ad5 genome, while the 58K family is (are) synthesized from a different initiation site(s). An antigen of 14K has been identified as a product of subregion 3 in region E4. This polypeptide is initiated by an AUG codon located in the Ad5 genome at 96.55 mu. Region E2A encodes three related products, the 72K and 47K DBPs described previously and a novel 64K polypeptide. Finally, two related products of 21K and 20K have been identified and these may be encoded by regions E3 or E4.</p> <p>The observations made on the antigens defined in this study are related to those described in other publications.</p>