Polyomaviruses BK and JC are ubiquitous viruses with high seroprevalence rates in general population.Following primary infection,polyomaviruses BK and JC persist latently in different sites,particularly in the reno-ur...Polyomaviruses BK and JC are ubiquitous viruses with high seroprevalence rates in general population.Following primary infection,polyomaviruses BK and JC persist latently in different sites,particularly in the reno-urinary tract.Reactivation from latency may occur in normal subjects with asymptomatic viruria,while it can be associated to nephropathy(PVAN)in kidney transplantat recipients.PVAN may occur in 1%-10%of renal transplant patients with loss of the transplanted organ in 30%up to 80%of the cases.Etiology of PVAN is mainly attributable to BK virus,although approximately5%of the cases may be due to JC.Pathogenesis of PVAN is still unknown,although viral replication and the lack of immune control play a major role.Immunosuppression represents the condicio sine qua non for the development of PVAN and the modulation of anti-rejection treatment represents the first line of intervention,given the lack of specific antiviral agents.At moment,an appropriate immunemodulation can only be accomplished by early identification of viral reactivacation by evaluation of polyomavirus load on serum and/or urine specimens,particularly in the first year post-trasplantation.Viro-immunological monitoring of specific cellular immune response could be useful to identify patients unable to recover cellular immunity posttransplantation,that are at higher risk of viral reactivation with development of PVAN.Herein,the main features of polyomaviruses BK and JC,biological properties,clinical characteristics,etiopathogenesis,monitoring and diag-nosing of PVAN will be described and discussed,with an extended citation of related relevant literature data.展开更多
Virus-specific immune responses have a major impact on the outcome of the infection. Viral agents that are characterized by latency, such as herpesviruses and polyomaviruses, require a continuous immune control to red...Virus-specific immune responses have a major impact on the outcome of the infection. Viral agents that are characterized by latency, such as herpesviruses and polyomaviruses, require a continuous immune control to reduce the extent of viral reactivation, as viral clearance cannot be accomplished, independently from the anti-viral treatment. In transplant patients, morbidity and mortality related to viral infections are significantly increased. In fact, the key steps of activation of T-cells are major target for anti-rejection immunosuppressive therapy and anti-viral immune response may be altered when infected cells and cellular effectors of immune response coexist in a transplanted organ. The role of cellular immune response in controlling viral replication and the main methods employed for its evaluation will be discussed. In particular, the main features, including both advantages and limitations, of available assays, including intracellular cytokine staining, major histocompatibility complex- multimer-based assays, Elispot assay, and Quanti FERON test, will be described. The potential applications of these assays in the transplant context will be discussed, particularly in relation to cytomegalovirus and polyomavirus BK infection. The relevance of introducing viro-immunological monitoring, beside virological monitoring, in order to identify the risk profile for viral infections in the transplant patients will allows for define a patient-tailored clinical management, particular in terms of modulation of immunosuppressive therapy and anti-viral administration.展开更多
文摘Polyomaviruses BK and JC are ubiquitous viruses with high seroprevalence rates in general population.Following primary infection,polyomaviruses BK and JC persist latently in different sites,particularly in the reno-urinary tract.Reactivation from latency may occur in normal subjects with asymptomatic viruria,while it can be associated to nephropathy(PVAN)in kidney transplantat recipients.PVAN may occur in 1%-10%of renal transplant patients with loss of the transplanted organ in 30%up to 80%of the cases.Etiology of PVAN is mainly attributable to BK virus,although approximately5%of the cases may be due to JC.Pathogenesis of PVAN is still unknown,although viral replication and the lack of immune control play a major role.Immunosuppression represents the condicio sine qua non for the development of PVAN and the modulation of anti-rejection treatment represents the first line of intervention,given the lack of specific antiviral agents.At moment,an appropriate immunemodulation can only be accomplished by early identification of viral reactivacation by evaluation of polyomavirus load on serum and/or urine specimens,particularly in the first year post-trasplantation.Viro-immunological monitoring of specific cellular immune response could be useful to identify patients unable to recover cellular immunity posttransplantation,that are at higher risk of viral reactivation with development of PVAN.Herein,the main features of polyomaviruses BK and JC,biological properties,clinical characteristics,etiopathogenesis,monitoring and diag-nosing of PVAN will be described and discussed,with an extended citation of related relevant literature data.
文摘Virus-specific immune responses have a major impact on the outcome of the infection. Viral agents that are characterized by latency, such as herpesviruses and polyomaviruses, require a continuous immune control to reduce the extent of viral reactivation, as viral clearance cannot be accomplished, independently from the anti-viral treatment. In transplant patients, morbidity and mortality related to viral infections are significantly increased. In fact, the key steps of activation of T-cells are major target for anti-rejection immunosuppressive therapy and anti-viral immune response may be altered when infected cells and cellular effectors of immune response coexist in a transplanted organ. The role of cellular immune response in controlling viral replication and the main methods employed for its evaluation will be discussed. In particular, the main features, including both advantages and limitations, of available assays, including intracellular cytokine staining, major histocompatibility complex- multimer-based assays, Elispot assay, and Quanti FERON test, will be described. The potential applications of these assays in the transplant context will be discussed, particularly in relation to cytomegalovirus and polyomavirus BK infection. The relevance of introducing viro-immunological monitoring, beside virological monitoring, in order to identify the risk profile for viral infections in the transplant patients will allows for define a patient-tailored clinical management, particular in terms of modulation of immunosuppressive therapy and anti-viral administration.
