RESUMO
Kaposi's sarcoma associated herpesvirus (KSHV) is subdivided into gamma-herpesvirus and causes Kaposi's sarcoma in human immunodeficiency virus (HIV)-infected patients. A defining feature of herpesviral biology is the presence of two alternative genetic lifestyles - a latent infection and a lytic replicative cycle. Almost all herpesviruses examined so far have been shown to express viral miRNAs in latently and/or productively infected cells. KSHV encodes an array of 15 distinct miRNAs, all of which are expressed at readily detectable levels in latently KSHV infected cells. The expression of an array of these viral miRNAs in KSHV-infected cells suggests that down-regulation of host cell mRNAs by miRNA-mediated RNA interference may represent a critical step in the establishment and/or maintenance of latent infections by KSHV. To investigate KSHV miRNAs that are expressed in KSHV-infected cells, KSHV-infected human umbilical cord vein endothelial cells (HUVECs) and BCBL-1 cells were used and their miRNAs were analyzed by a modified real-time PCR method. Some KSHV miRNAs were detected in KSHV-infected HUVECs and their expression was affected by genetic life cycles. In addition, KSHV miRNAs were also detected in BCBL-1 and their expression was not related to treatment of sodium butyrate. These results indicate that KSHV infection in cells inducing KSHV miRNAs expression would be increased upon entry into latent replication.