Cytomegalovirus (CMV) genotype in allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Based on sequence variation in the UL55 gene that encodes glycoprotein B (gB), human cytomegalovirus (CMV) can be classified into four gB genotypes. Previous studies have suggested an association between CMV gB genotype and clinical outcome in patients who underwent an allogeneic hematopoietic stem cell transplant (HSCT). The goals of this study were identify patients with active infection caused by CMV in recipients of HSCT; determine the prevalence of CMV genotypes in the study group; correlate genotype with CMV disease, acute GVHD and overall survival. METHODS: The diagnosis of active CMV infection after allogeneic HSCT was detected by antigenemia (AGM) and/or nested-PCR (N-PCR). Positive samples from patients with active CMV infection were submitted to genotyping using N-PCR to amplify a region of UL55, followed by restriction analysis based on HinfI and RsaI digestion. Real-time PCR (qPCR) was used to determine the viral load during active CMV infection and antiviral treatment. RESULTS: Sixty-three allogeneic HSCT recipients were prospectively evaluated; 49/63 (78%) patients were infected with CMV genotypes - gB1 19/49 (39%), gB2 17/49 (35%), gB3 3/49 (6%), gB4 7/49 (14%) - and 3 (6%) had mixed CMV genotypes (gB1 + gB3, gB1 + gB4 and gB2 + gB4). Characterized by gastrointestinal disease, CMV disease occurred in 3/49 (6.1%) patients, who had CMV gB3 genotype. These gB3 genotype patients presented an increasing AGM number, mean 125 (± 250) (P = 0.70), and qPCR copies/ml, mean 37938 (SD ± 50542) (P = 0.03), during antiviral treatment, when compared with other CMV genotypes. According to CMV genotypes, stratified overall survival was 55% for gB1, 43% for gB2; 0% for gB3 and 57% for gB4 (P = 0.03). CONCLUSIONS: One of the restrictions of the presented study was the low number of CMV gB sub-cohorts). However, we demonstrated that the frequency of active CMV infection in this HSCT population was high, and the most prevalent genotype in these patients with active CMV infection was gB1 and gB2 genotype (74%). In Brazil, HSCT recipients seem to carry mainly gB1 and gB2 CMV genotype.

Surveillance of active human cytomegalovirus infection in hematopoietic stem cell transplantation (HLA sibling identical donor): search for optimal cutoff value by real-time PCR.

BACKGROUND: Human cytomegalovirus (CMV) infection still causes significant morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). Therefore, it is extremely important to diagnosis and monitor active CMV infection in HSCT patients, defining the CMV DNA levels of virus replication that warrant intervention with antiviral agents in order to accurately prevent CMV disease and further related complications. METHODS: During the first 150 days after allogeneic HSTC, thirty patients were monitored weekly for active CMV infection by pp65 antigenemia, nested-PCR and real-time PCR assays. Receiver operating characteristic (ROC) plot analysis was performed to determine a threshold value of the CMV DNA load by real-time PCR. RESULTS: Using ROC curves, the optimal cutoff value by real-time PCR was 418.4 copies/104 PBL (sensitivity, 71.4%; specificity, 89.7%). Twenty seven (90%) of the 30 analyzed patients had active CMV infection and two (6.7%) developed CMV disease. Eleven (40.7%) of these 27 patients had acute GVHD, 18 (66.7%) had opportunistic infection, 5 (18.5%) had chronic rejection and 11 (40.7%) died - one died of CMV disease associated with GVHD and bacterial infection. CONCLUSIONS: The low incidence of CMV disease in HSCT recipients in our study attests to the efficacy of CMV surveillance based on clinical routine assay. The quantification of CMV DNA load using real-time PCR appears to be applicable to the clinical practice and an optimal cutoff value for guiding timely preemptive therapy should be clinically validated in future studies.