Complete genome sequence of transmissible gastroenteritis coronavirus PUR46-MAD clone and evolution of the purdue virus cluster

The complete sequence (28580 nt) of the PUR46-MAD clone of the Purdue clust er of transmissible gastroenteritis coronavirus (TGEV) has been determined and compared with members of this cluster and other coronaviruses. The comp uting distances among their S gene sequences resulted in the grouping of th ese coronaviruses into four clusters, one of them exclusively formed by the Purdue viruses. Three new potential sequence motifs with homology to the a lpha -subunit of the polymerase-associated nucleocapsid phosphoprotein of r inderpest virus, the Bowman-Birk type of proteinase inhibitors, and the met allothionein superfamily of cysteine rich chelating proteins have been iden tified. Comparison of the TGEV polymerase sequence with that of other RNA v iruses revealed high sequence homology with the A-E domains of the palm sub domain of nucleic acid polymerases.