MOLECULAR CHARACTERIZATION OF THE TYPE-SPECIFIC GAMMA-DETERMINANT LOCATED ON THE ADENOVIRUS FIBER

The fiber knob carries the type-specific gamma-antigen which ran he de monstrated in hemagglutination inhibition tests, In order to character ize the gamma-determinant we selected subgenus DI adenovirus serotypes 9 and 19 (Ad9 and Ad19) which exhibited 29 amino acid exchanges in th e knob domain, Like all subgenus DI adenoviruses they showed a complet e hemagglutination pattern with rat and human erythrocytes. We constru cted a total of 14 chimeric Ad9/Ad19 and Ad19/Ad9 fiber proteins, whic h possessed fiber knobs with progressively exchanged Ad9 and Ad19 amin o acids. Furthermore, we created 39 fiber proteins with distinct amino acid exchanges in the knob regions by primer-directed mutagenesis. Th e proteins were expressed in Escherichia coli and tested in hemaggluti nation and hemagglutination inhibition tests. From our results we can conclude that the type-specific gamma-determinant is not restricted to a distinct region on the adenovirus fiber knob but is composed of at least 17 amino acids. Most of the amino acids contributing to the Ad9 and Ad19 gamma-determinants are located on the fiber knob loops.