HUMAN AND SIMIAN ADENOVIRUSES - PHYLOGENETIC INFERENCES FROM ANALYSISOF VA RNA GENES

Adenovirus VA RNA genes have primary sequence constraints due to inter nal promoter regions and a high degree of secondary structure in the R NA product To determine the relationships between human and simian ade noviruses, the VA RNA genes of several primate adenoviruses were chara cterized and compared to those sequences already published. Human aden oviruses of subgenera A, B:2, and F have only one VA RNA gene, whereas human adenoviruses of subgenera B:1, C, D, and E have two. The genome s of 12 monkey adenoviruses were found to have only one VA RNA gene, w hereas the genomes of six representative chimpanzee adenoviruses were each found to have two VA RNA genes. Phylogenetic analysis of represen tative VA RNA gene sequences individually, irrespective of their strai n of origin or partnering VA RNA gene, gave the following inferences. (1) The single VA RNA genes of human adenovirus subgenera A and F are most closely related to those of monkey adenoviruses. (2) The VA RNA, genes of human adenoviruses in subgenera B:1, D, and E, and also the s ingle VA RNA genes of subgenus B:2 probably diverged from a common anc estral VA RNA gene. (3) This ancestral gene most likely reduplicated t o give the precursor of all VA RNA(II) genes, the evidence for which h as been almost totally lost in subgenus B:2 adenoviruses. (4) The two VA RNA genes of human subgenus C adenoviruses are relatively distant f rom each other phylogenetically. Since the Ad2 and Ad5 VA RNA(1) genes have a higher identity to the single VA RNA gene of SAV13 (SV36) than to those of any of the other human adenoviruses, these genes may have entered the human subgenus C adenovirus genome by substitution involv ing recombination with a simian adenovirus. The results of this study suggest that a renewed appraisal of VA RNA function in adenoviruses ot her than Ad2 and Ad5 may be necessary. (C) 1995 Academic Press, Inc.