Human cytomegalovirus UL141 protein interacts with CELF5 and affects viral DNA replication

Human cytomegalovirus (HCMV) infection is the primary viral cause of congenital abnormalities and mental retardation in newborns. The HCMV UL141‑encoded glycoprotein has been previously revealed to inhibit the cell‑surface expression of cluster of differentiation (CD)155, CD122, tumor necrosis factor‑related apoptosis‑inducing ligand death (TRAIL)‑receptor 1 (R1) and TRAIL‑receptor 2 (R2), thus protecting virally‑infected cells by allowing them to escape natural killer cell‑mediated cytotoxicity. The present study investigated the interaction between HCMV UL141 and human fetal brain cDNA to elucidate the possible effects of UL141 on the nervous system. The findings of the current study demonstrate that the HCMV UL141 protein directly interacts with the human protein CUGBP Elav‑like family member 5 (CELF5) via yeast two‑hybrid screening, this interaction was confirmed by glutathione S‑transferase pull‑down and co‑immunoprecipitation assays. Additionally, the present study demonstrated that the UL141 protein co‑localizes with CELF5 in the cytoplasm of 293 cells using fluorescence confocal microscopy. CELF5 overexpression in a stably‑expressing cell line significantly increased viral DNA copy number and titer in HCMV‑infected U373MG cells. However, reducing CELF5 expression via specific small interfering RNAs did not affect viral DNA copy number or titer in HCMV‑infected cells. The current findings suggest that the interaction between UL141 and CELF5 may be involved in modulating viral DNA synthesis and progeny production. Therefore, CELF5 may represent a possible mechanism for regulation of HCMV genomic DNA synthesis, which is a key step during HCMV infection leading to neurological disease.