Expression Profile of Cmvil-10 and Lacmvil-10 Transcripts of the Ul111a Gene of Human Cytomegalovirus (Hcmv) in Vitro in Primary Cells and in Vivo in Cells From Renal Transplant Patients

Human cytomegalovirus (HCMV) is a high-risk pathogen in immunocompromised individuals, especially transplant recipients, in whom viremia must be monitored and treated when necessary. HCMV has multiple strategies to modulate host antiviral responses, including the UL111A gene, a viral homolog of cellular interleukin-10 (cIL-10), which, through alternative splicing, generates multiple transcripts and isoforms. The cmvIL-10 protein has properties similar to cIL-10, whereas LAcmvIL-10 has more restricted biological properties. Here, we investigated the expression of cmvIL-10 and LAcmvIL-10 transcripts in vitro during productive and latent infection and in vivo in peripheral blood mononuclear cells (PBMCs) from renal transplant recipients. In vitro, RNA was extracted from productively infected cells (MRC-5) and latently infected cells (CD14+ monocytes) with HCMV at different times post-infection (24h to 120h). Relative expression of cmvIL-10 and LAcmvIL-10 normalized to GAPDH was evaluated by RT-qPCR. In vivo, PBMCs from transplant recipients were collected pre-transplant and pre-immunosuppression, on the day of the procedure, and on days 7, 21, 45, and 60 post-transplant. Blood samples were also collected when HCMV was first detected in patients and at the beginning and end of antiviral treatment (ganciclovir). Absolute detection of cmvIL-10 and LAcmvIL-10 transcripts and relative detection of intracellular viral DNA (UL44) were performed by (RT)qPCR. In vitro, both transcripts were detected at varying levels depending on the time point, during both lytic infection (MRC-5) and latent infection (CD14+), although LAcmvIL-10 levels were almost always higher than cmvIL-10 levels. In patient PBMCs, LAcmvIL-10 was detected only sporadically and in a few patients, whereas cmvIL-10 was found in all patients at all time points analyzed. Moreover, in PBMCs, cmvIL-10 expression was positively associated with increased detection of viral DNA at the subsequent collection, suggesting that cmvIL-10 expression may precede viral DNA replication. These data contribute to our understanding of HCMV biology in different phases of infection. Additionally, this initial analysis suggests that combined monitoring of cmvIL-10 and viral DNA may improve early detection of HCMV reactivation in renal transplant recipients.