Coding potential of UL/b′ from the initial source of rhesus cytomegalovirus Strain 68-1

Rhesus cytomegalovirus (RhCMV) 68-1 is the prototypic strain of RhCMV that has been used for pathogenesis and vaccine development. We determined the complete sequence of the RhCMV 68-1 UL/b′ region directly from the original urine from which RhCMV 68-1 was isolated in 1968, and compared it to other RhCMVs. The laboratory passaged RhCMV 68-1 has inversions, deletions, and stop codons in UL/b′ that are absent in the original isolate and other low passage RhCMV isolates. Fourteen of the 17 open reading frames (ORFs) in 68-1 UL/b′ in the original isolate share >95% amino acid identity with low passage RhCMV. The original isolate retains 6 ORFs that encode α-chemokine-like proteins, including RhUL146 and RhUL146b that share only 92% and 81% amino acid identity, respectively, with a contemporary low passage RhCMV isolate. Identification of the original RhCMV 68-1 UL/b′ sequence is important for using RhCMV 68-1 in pathogenesis and vaccine studies.