THE GENOMIC SEQUENCE-ANALYSIS OF THE LEFT AND RIGHT SPECIES-SPECIFIC TERMINAL REGION OF A COWPOX VIRUS-STRAIN REVEALS UNIQUE SEQUENCES AND A CLUSTER OF INTACT ORFS FOR IMMUNOMODULATORY AND HOST-RANGE PROTEINS

Sequencing and computer analysis of the left (52,283 bp) and right (49 ,649 bp) variable DNA regions of the cowpox virus strain GRI-90 (CPV-G RI) has revealed 51 and 37 potential open reading frames (ORFs), respe ctively. Comparison of the structure-function organization of these DN A regions of CPV-GRI with those previously published for corresponding regions of genomes of vaccinia virus, strains Copenhagen (VAC-COP) an d Western Reserve (VAC-WR); and variola major virus, strains India-196 7 (VAR-IND), Bangladesh-1975 (VAR-BSH); and alastrim variola minor vir us, strain Garcia-1966 (VAR-GAR), was performed. Within the left termi nal region under study, an extended DNA sequence (14,171 bp), unique t o CPV, has been found. Within the right region of the CPV-GRI genome t wo segments, which are unique to CPV DNA (1579 and 3585 bp) have been found. Numerous differences have been revealed in the genetic structur e of CPV-GRI DNA regions, homologous to fragments of the genomes of th e above-mentioned orthopoxvirus strains. A cluster of ORFs with struct ural similarity to immunomodulatory and host range function of other p oxviruses have also been detected. A comparison of the sequences of OR F B, crmA, crmB, crmC, IMP, and CHO hr genes of CPV Brighten strain (C PV-BRI) with the corresponding genes in strain GRI-90 have revealed an identity at the amino acid level ranging from 82 to 96% between the t wo strains. The findings are significant in light of the recent demons tration of CW as an important poxvirus model system to probe the preci se in vivo role(s) of the unique virally encoded immunomodulatory prot eins. Also, the presence of a complete and intact repertoire of immuno modulatory proteins, ring canal proteins family, and host range genes indicates that CPV may have been the most ancient of all studied ortho poxviruses. (C) 1998 Academic Press.