Indirect Effects of Cytomegalovirus Infection
Primary cytomegalovirus (CMV) infection often presents as an asymptomatic self-limiting disease in immunocompetent individuals and is followed by latent persistence in different host tissues. However, solid organ transplant (SOT) recipients and patients undergoing allogeneic haematopoietic stem cell transplantation (alloHSCT) are at risk of life-threatening complications caused by CMV infection. Direct effects (or CMV disease) are marked by viral proliferation in a variety of tissues and organs. Clinical manifestations that are observed after SOT and alloHSCT are gastroenteritis, pneumonitis, hepatitis, uveitis, retinitis, encephalitis and graft rejection. In contrast to the direct effects, indirect effects are a consequence of the maintenance of persistent low-level viral replication and have been associated with an increased risk of rejection and graft dysfunction, graft-versus-host disease, accelerated atherosclerosis, opportunistic infections, malignancies, posttransplant diabetes and Guillain-Barré syndrome. This article aims to summarise these indirect effects of CMV, their possible causes and possible treatment strategies.