Functional analysis of Kaposi's sarcoma-associated herpesvirus RTA in an RTA-depressed cell line.
OBJECTIVE
The viral transcriptional activator encoded by Kaposi's sarcoma-associated herpesvirus (KSHV) open reading frame 50 (RTA) is expressed in the immediate-early phase of reactivation. We isolated an RTA-depressed cell line, BLS50-4, by subcloning from the KSHV-infected cell line, BCBL-1.


RESULTS
In addition to RTA, induction of some lytic gene expressions was also remarkably reduced in BLS50-4 cells, but that of the K8.1 and ORF65 gene expressions was not. Both the replication of the KSHV genome and the release of KSHV DNA into the medium were greatly reduced. Transfection of RTA into BLS50-4 cells restored the expression of K9 (vIRF) and ORF59, but not K8.1.


CONCLUSIONS
Thus, we showed that expression of late genes was not directly controlled by RTA, unlike the other groups concluded. We also showed that, by isolating the RTA-depressed cell line, the RTA protein had a critical role in viral DNA replication and the expression of several lytic genes.
Nishimura
K
K
Department of Microbiology, Osaka University Medical School, Osaka, Japan.
Ueda
K
K
Sakakibara
S
S
Ishikawa
K
K
Chen
J
J
Okuno
T
T
Yamanishi
K
K
D002460:Cell Line; D004261:DNA Replication; D004279:DNA, Viral / Q000096:biosynthesis; D015967:Gene Expression Regulation, Viral; D019288:Herpesvirus 8, Human / Q000235:genetics* / Q000502:physiology; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics*; D016296:Mutagenesis; D015534:Trans-Activators / Q000235:genetics*; D014162:Transfection; D014764:Viral Proteins / Q000235:genetics*; D014779:Virus Replication
D004279:DNA, Viral; D017874:Immediate-Early Proteins; C417604:Rta protein, Human herpesvirus 8; D015534:Trans-Activators; D014764:Viral Proteins