Abstract
Purpose :
Active cytomegalovirus (CMV) infection mimicking acute allograft rejection in corneal transplant recipients (CMV endotheliitis) has been recently reported predominantly in East Asian populations with high CMV seroprevelence. In this study we retrospectively examined corneal grafts that have failed due to rejection to determine the prevalence of CMV infection in the UK.
Methods :
We searched a national ophthalmic pathology referral service database between 1998 and 2014 using the search terms ‘rejection’ OR ‘rejected.’ We identified 238 corneal samples suitable for screening, of which 132 patients were from Moorfields. We retrieved the medical records to extract the clinical details and confirm, or exclude, the diagnosis of endothelial rejection. We included penetrating and endothelial keratoplasties but excluded anterior lamellar grafts and eyes with concomitant microbial keratitis or endophalthmitis. Failed grafts without documented evidence of endothelial rejection served as controls.
From the paraffin-embedded tissue we extracted nucleic acids before amplifying regions of CMV, herpes simplex virus (HSV) and varicella zoster virus (VZV) using nested quantitative PCR. We used the following primers: glycoprotein B gene gB (CMV), ssDNA-binding protein gene found on ORF29 (VZV) and glycoprotein D gene (HSV). We validated the nucleic extraction process from formalin-fixed tissue using a 1992 retinal sample (separately confirmed CMV-positive by in situ hybridisation). PhiX PCR inhibition assays were performed indicating that there was no inhibition of PCR. Positive control material for all 3 virus were additionally tested. A CMV-positive result was considered clinically significant if the same tissue was also negative for HSV and VZV.
Results :
The medical records of 103 patients (74%) could be traced. We confirmed a clinical history of rejection in 47 samples of 47 unique patients, with 38 graft failures without rejection (unique controls). 18 patients did not meet the inclusion criteria or lacked sufficient details to confirm or exclude a rejection episode. No CMV or VZV nucleic acid was detected in either the rejection or control groups. One control sample was positive for HSV.
Conclusions :
CMV endothelitiis is not a significant cause of corneal graft failure in the UK. This may also apply to other countries with similarly low CMV seroprevelence.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.