The rat cytomegalovirus homologue of parvoviral rep genes, r127, encodes a nuclear protein with single- and double-stranded DNA-binding activity that is dispensable for virus replication.
An intriguing feature of the rat cytomegalovirus (RCMV) genome is open reading frame (ORF) r127, which shows similarity to the rep genes of parvoviruses as well as the U94 genes of human herpesvirus type 6A (HHV-6A) and 6B (HHV-6B). Counterparts of these genes have not been found in other herpesviruses. Here, it is shown that the r127 gene is transcribed during the early and late phases of virus replication in vitro as an unspliced 1.1 kb transcript containing the complete r127 ORF. Transcripts of r127 were also detected in various organs of RCMV-infected rats at 1 week post-infection (p.i.), but only in the salivary gland at 4 months p.i. Using rabbit polyclonal antibodies raised against the r127-encoded protein (pr127), pr127 was found to be expressed as early as 12 h p.i. within the nuclei of RCMV-infected cells in vitro. Expression of pr127 was also observed within the nuclei of cells in various organs of RCMV-infected rats at 3 weeks p.i. Moreover, pr127 was demonstrated to bind single- as well as double-stranded DNA. Finally, an RCMV r127 deletion mutant (RCMVDeltar127) was generated, in which the r127 ORF was disrupted. This deletion mutant, however, was shown to replicate with a similar efficiency as wild-type RCMV (wt RCMV), both in vitro and in vivo. Taken together, it is concluded that the RCMV r127 gene encodes a nuclear protein with single- and double-stranded DNA-binding activity that is dispensable for virus replication, not only in vitro, but also during the acute phase of infection in vivo.
van Cleef
Koen W R
KWR
Department of Medical Microbiology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
Scaf
Wendy M A
WMA
Department of Medical Microbiology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
Maes
Karen
K
Department of Medical Microbiology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
Kaptein
Suzanne J F
SJF
Department of Medical Microbiology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
Beuken
Erik
E
Department of Medical Microbiology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
Beisser
Patrick S
PS
Department of Medical Microbiology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
Stassen
Frank R M
FRM
Department of Medical Microbiology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
Grauls
Gert E L M
GELM
Department of Medical Microbiology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
Bruggeman
Cathrien A
CA
Department of Medical Microbiology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
Vink
Cornelis
C
Department of Medical Microbiology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D003587:Cytomegalovirus / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D017931:DNA Primers; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015654:Herpesvirus 6, Human / Q000235:genetics / Q000502:physiology; D006801:Humans; D008099:Liver / Q000473:pathology / Q000821:virology; D008297:Male; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics; D017992:Parvovirus / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics / Q000302:isolation & purification; D051381:Rats; D017208:Rats, Wistar; D012469:Salivary Glands / Q000473:pathology / Q000821:virology; D013154:Spleen / Q000473:pathology / Q000821:virology; D015678:Viral Structural Proteins / Q000235:genetics / Q000378:metabolism*
D017931:DNA Primers; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012367:RNA, Viral; D015678:Viral Structural Proteins