Objective:To study the effect of human immunodeficiency virus type 1(HIV-1) transactivative transcription protein(Tat) on Kaposi’s sarcoma-associated herpesvirus(KSHV) infecting SK-N-SH neuroblastoma cells(SK cells). Methods:After co-culturing body cavity-based lymphoma 1[BCBL-1, originated from primary effusion lymphoma(PEL)] cells and SK cells, the cytopathic effect(CPE) of SK cells was observed and the replication of KSHV in SK cells was detected by Real-time PCR. SK cells were transfected with recombinant plasmid Tat+pcDNA3.1(+) and empty vector pcDNA3.1(+), respectively. The stably transfected cell clones were obtained through G418 screening. The expression of Tat in SK cells was detected by reverse transcription polymerase chain reaction(RT-PCR) and Western blot. Real-time PCR were further performed to evaluate the expression of KSHV lytic cycle genes ORF50 and ORF26 mRNA after co-culturing BCBL-1 cells with SK-Tat or SK-vector cells. Results:After SK and BCBL-1 cells co-culture, CPE appeared in SK cells and KSHV ORF50 mRNA was expressed in SK cells. The specific band of Tat appeared as expected both in RT-PCR and Western blot detection. Real-time PCR showed that Tat decreased the expression of KSHV ORF50 and ORF26 mRNA. Conclusion:Preliminary research indicated that Tat might inhibit KSHV lytic cycle replication in SK cells during cell co-culture.