Prevalence and Impact of Cytomegalovirus Primary Infection and Reactivation on Graft Function in Post-Renal Transplant Recipients

Introduction Cytomegalovirus (CMV) is often associated with mortality and significant morbidity following renal transplantation leading to graft rejection or dysfunction. Primary CMV infection refers to the first detection of the virus in a person who has no prior evidence of CMV exposure before transplantation. CMV has a unique property called latency. After the initial infection, CMV can enter a dormant state within the body, residing in myeloid cells without causing active disease. CMV reactivation is likely when a latent CMV infection switches to a lytic phase of replication, which can be detected using IgG avidity ELISA. Aims and objectives This study aims to assess the prevalence of primary CMV infection and reactivation in renal transplant recipients, evaluate the impact of CMV infection on graft function following transplantation, and identify the risk factors and comorbidities associated with CMV-related graft rejection. Methodology During the study period from March 2020 to November 2021, blood samples were collected from 46 CMV-positive (by PCR) renal transplant recipients, and serum was separated and stored. IgG avidity ELISA test was performed, which served as a valuable tool to differentiate primary infection from reactivation due to difference in binding strength where low binding strength (low avidity<30%) indicated primary infection and high binding strength (high avidity>40%) indicated reactivation. All these patients were followed up to study the impact of CMV on graft functions. Results The age-wise distribution of patients shows a maximum number of cases under 40 years. The gender distribution of cases shows a higher preponderance of males (76%) compared to females (24%). The clinical presentation showed CMV syndrome as the most common (50%), followed by CMV colitis (37%), CMV nephritis (9%), CMV pneumonitis, CMV esophagitis, and CMV duodenitis, each comprising 2%. After performing the IgG avidity test, CMV infection with maximum cases of reactivation (87%) followed by primary infection (13%) was observed. The investigations related to renal dysfunction such as serum creatinine showed >3 mg/dL (85% of cases), 2.1-3 mg/dL (4.33% of cases), 1.6-2 mg/dL (2% of cases), 1-1.5 mg/dL (4.33% of cases) in decreasing order. Normal urea values are seen in 9% of cases followed by the range between 24 and 55 mg/dL in 67% and >100% in 24% of cases. The graft rejection based on the biopsy report showed that acute cellular rejection (ACR) (72%) was higher followed by antibody-mediated rejection (ABMR) with 15% and then ACR + ABMR with 4%. No rejection was found in 9% of cases. Renal dysfunction showed a higher preponderance to chronic graft dysfunction (67%) followed by acute graft dysfunction (24%) and stable graft function among 9% of cases. A comparison of graft dysfunction in primary infection/reactivation was assessed, and it was found that acute graft dysfunction was more common in primary infection. In the case of reactivation, chronic graft dysfunction was more common. Conclusion This study focuses on the microbiological dimensions and the critical role of CMV antibody screening. It underscores the necessity of vigilant monitoring and prophylactic antiviral therapy to reduce CMV infection risks and enhance patient outcomes. It also highlights the use of IgG avidity testing to differentiate between primary infection and reactivation, facilitating timely and effective interventions to prevent graft dysfunction and rejection.