COVID-19 in hematopoietic stem cell transplant recipients during three years of the pandemic: a multicenter study in Brazil

ABSTRACT Hematopoietic stem cell transplant (HSCT) recipients are at -increased risk for severe COVID-19. The aim of this study was to evaluate the burden of COVID-19 in a cohort of HSCT recipients. This retrospective study evaluated a cohort of adult hospitalized HSCT recipients diagnosed with COVID-19 in two large hospitals in São Paulo, Brazil post-HSCT, from January 2020 to June 2022. The primary outcome was all-cause mortality. Of 49 cases, 63.2% were male with a median age of 47 years. Allogeneic-HSCT (51.2%) and autologous-HSCT (48.9%) patients were included. The median time from HSCT to COVID-19 diagnosis was 398 days (IQR: 1211-134), with 22 (44.8%) cases occurring within 12 months of transplantation. Most cases occurred during the first year of the pandemic, in non-vaccinated patients (n=35; 71.4%). Most patients developed severe (24.4%) or critical (40.8%) disease; 67.3% received some medication for COVID-19, primarily corticosteroids (53.0%). The probable invasive aspergillosis prevalence was 10.2%. All-cause mortality was 40.8%, 51.4% in non-vaccinated patients and 14.2% in patients who received at least one dose of the vaccine. In the multiple regression analyses, the variables mechanical ventilation (OR: 101.01; 95% CI: 8.205 - 1,242.93; p = 0.003) and chest CT involvement at diagnosis ≥50% (OR: 26.61; 95% CI: 1.06 - 664.26; p = 0.04) remained associated with all-cause mortality. Thus, HSCT recipients with COVID-19 experienced high mortality, highlighting the need for full vaccination and infection prevention measures.

Prevalence and clinical consequences of Hepatitis C virus infection in patients undergoing hematopoietic stem cell transplantation

ABSTRACT Hepatitis C virus (HCV) infection is a significant cause of morbidity and mortality among hematopoietic stem cell transplant (HCT) recipients. In Brazil, its occurrence in HCT recipients remains undetermined. We now report on HCV prevalence in HCT recipients and its clinical consequences. The medical records of all HCT recipients seen at Hospital das Clinicas, Sao Paulo University Medical School, from January 2010 to January 2020 were reviewed to determine HCV serostatus. A retrospective analysis of medical charts was undertaken on all seropositive cases to determine HCV genotype, presence of liver fibrosis, co-infections with other viruses, previous treatments, and clinical evolution of liver pathology after HCT. Of the 1,293 HCT recipients included in the study, seven (0.54%) were HCV antibody-positive and five (0.39%) were also viremic for HCV-RNA. Four of these individuals had moderate to severe liver fibrosis (METAVIR F2/F3) and one was cirrhotic. Two of the viremic patients developed acute liver dysfunction following transplantation. All patients had their acute episode of liver dysfunction resolved with no further complications. Four of the viremic patients were treated for HCV infection with direct acting agents (DAA). Information regarding HCV treatment was lacking for one of the viremic HCV patients due to loss of follow up. Sustained anti-virologic responses were observed in three cases after the use of DAA. The detection of HCV in hematological adults undergoing HCT and its successful treatment with DAA highlight the necessity of testing for HCV both prior to and following transplantation.

Multiple myeloma and Chagas disease: qPCR as a marker for preemptive antiparasitic therapy: a case reports series and review

ABSTRACT Multiple myeloma (MM) associated with Chagas disease is rarely described. This disease and its therapy suppress T cell and macrophage functions and increase regulatory T cell function, allowing the increase of parasitemia and the risk of Chagas Disease Reactivation (CDR). We aimed to analyze the role of conventional (cPCR) and quantitative Polymerase Chain Reaction (qPCR) for prospective monitoring of T. cruzi parasitemia, searching for markers of preemptive antiparasitic therapy in MM patients with Chagas disease. Moreover, we investigated the incidence and management of hematological diseases and CDR both inside and outside the transplant setting in the MEDLINE database. We found 293 studies and included 31 of them. Around 1.9-2.0% of patients with Chagas disease were reported in patients undergoing Stem Cell Transplantation. One case of CDR was described in eight cases of MM and Chagas disease. We monitored nine MM and Chagas disease patients, seven under Autologous Stem Cell Transplantation (ASCT), during 44.56±32.10 months (mean±SD) using parasitological methods, cPCR, and qPCR. From these patients, three had parasitemia. In the first, up to 256 par Eq/mL were detected, starting from 28 months after ASCT. The second patient dropped out and died soon after the detection of 161.0 par Eq/mL. The third patient had a positive blood culture. Benznidazole induced fast negativity in two cases; followed by notably lower levels in one of them. Increased T. cruzi parasitemia was related to the severity of the underlying disease. We recommend parasitemia monitoring by qPCR for early introduction of preemptive antiparasitic therapy to avoid CDR.

Extracellular vesicles are a late marker of inflammation, hypercoagulability and COVID-19 severity

ABSTRACT Exacerbated inflammation and coagulation are a hallmark of COVID-19 severity. Extracellular vesicles (EVs) are intercellular transmitters involved in inflammatory conditions, which are capable of triggering prothrombotic mechanisms. Since the release of EVs is potentially associated with COVID-19-induced coagulopathy, the aim of this study was to evaluate changes in inflammation- and hypercoagulability-related EVs during the first month after symptom onset and to determine whether they are associated with disease severity. Blood samples of patients with mild or severe forms of the disease were collected on three occasions: in the second, third and fourth weeks after symptom onset for the quantification by flow cytometry of CD41A (platelet glycoprotein IIb/IIIa), CD162 (PSGL-1), CD31 (PECAM-1) and CD142 cells (tissue factor). Analysis of variance (ANOVA) with repeated measures, Kruskal-Wallis and correlation tests were used. Eighty-five patients were enrolled, 71% of whom had mild disease. Seventeen uninfected individuals served as controls. Compared to controls, both mild and severe COVID-19 were associated with higher EV-CD31+, EV-CD41+ and EV-CD142+ levels. All EV levels were higher in severe than in mild COVID-19 only after the third week from symptom onset, as opposed to C-reactive protein and D-dimer levels, which were higher in severe than in mild COVID-19 earlier during disease progression. EV levels were also associated with C-reactive protein and D-dimer levels only after the third week of symptoms. In conclusion, EVs expressing CD41A, CD31, TF, and CD162 appear as late markers of COVID-19 severity. This finding may contribute to the understanding of the pathogenesis of acute and possibly long COVID-19.

Comparison of characteristics and laboratory tests of COVID-19 hematological patients from France and Brazil during the pre-vaccination period: identification of prognostic profiles for survival

ABSTRACT Introduction: COVID-19 disease presentation is heterogeneous, from asymptomatic up to severe life-threatening forms. Getting further insights into patients with specific diseases is of particular interest. We aimed to identify profiles of hematology patients hospitalized with COVID-19 that would be associated with survival and to assess the differences between cohorts Methods: A binational cohort of 263 patients with COVID-19 and hematological disease was studied in Paris, France and São Paulo, Brazil. Patient profiles were based on age, comorbidities, biological measurements, COVID-19 symptoms and hematological disease characteristics. A semi-supervised learning method with a survival endpoint was first used, following which, a classifier was identified to allow the classification of patients using only baseline information Main results: Two profiles of patients were identified, one being young patients with few comorbidities and low C-reactive protein (CRP), D-dimers, lactate dehydrogenase (LDH) and creatinine levels, and the other, older patients, with several comorbidities and high levels of the 4 biology markers. The profiles were strongly associated with survival (p < 0.0001), even after adjusting for age (p = 0.0002). The 30-day survival rate was 77.1% in the first profiles, versus 46.7% in the second. The Brazilian analysis emphasized the importance of age, while the French focused on the comorbidities Conclusion: This analysis showed the importance of CRP, LHD and creatinine in the COVID-19 presentation and prognosis, whatever the geographic origin of the patients.

Detection of alloimmunization in Glanzmann Thrombasthenia and Bernard-Soulier Syndrome: Data from a Brazilian Center

ABSTRACT Introduction: The Glanzmann Thrombasthenia (GT) and Bernard-Soulier Syndrome (BSS) are rare hereditary disorders of platelet function. Their treatment often requires platelet transfusion, which can lead to the development of alloantibodies. Objective: In this study, we aim to develop a strategy for alloantibody detection and to describe the frequency of alloimmunization in a patient population from a single center in southeastern Brazil. Methods: Samples from patients with GT or BSS were tested using the Platelet Immunofluorescence Test (PIFT). If a positive result was obtained, a confirmatory step using the Monoclonal Antibody Immobilization of Platelet Antigens (MAIPA) and Luminex bead-based platelet assay (PAKLx) was executed. Main results: Among 11 patients with GT, we detected the presence of alloantibodies in 5 using PIFT, with confirmation through MAIPA and PAKLx in 2 (1 anti-HLA and 1 anti-HPA), resulting in a frequency of 18.1%. Among 4 patients with BSS, PIFT was positive in 3, with confirmation by MAIPA and PAKLx in 1 (anti-HLA), showing a frequency of 25%. The two patients with anti-HLA antibodies exhibited a panel reactive antibody (PRA-HLA) testing greater than 97%. Conclusion: Our study highlights the importance of identifying platelet alloimmunization in this patient population. The proposed algorithm for platelet alloantibodies detection allows resource optimization.

External quality control program in infectious diseases screening at laboratories and blood banks in Latin America: an analysis of the past 5 years / Programa de control externo de la calidad en el tamizaje de enfermedades infecciosas en laboratorios y bancos de sangre de América Latina: análisis de los últimos 5 años / Programa externo de controle de qualidade na triagem de doenças infecciosas em laboratórios e bancos de sangue da América Latina: análise dos últimos 5 anos

ABSTRACT Objective. To evaluate the screening of blood samples for infectious disease markers at laboratories and blood banks in Latin America per the findings of an External Quality Assessment Program (EQAP). Methods. This qualitative analysis used data from the EQAP coordinated by the Fundação Pro Sangue Hemocentro de São Paulo with the support of the Pan American Health Organization to assess the performance of blood screening for infectious diseases from 2014 to 2018 in Latin America. Each participating laboratory or blood bank received an identical blind panel with 24 blood samples with variable reactivity for all the screening parameters. Panels were processed at each participating facility and results were returned to the Fundação Pro Sangue Hemocentro de São Paulo for individual and joint analyses. Two types of discrepant results were potential failures: false positive results (FPRs) and false nonreactive results (FNRRs). Results. A total of 23 136 samples were evaluated. Global rates of FPR, FNRR, and concordant results were 0.3%, 1.0% and 98.7%, respectively. Seven FNRRs were found for HBsAg (1.0%), 12 for syphilis (2.6%), and 21 for Chagas disease (2.9%). No FNRRs were found for the HIV, HCV, and HTLV viruses. The average accuracy of all the laboratories and blood banks participating in the EQAP during the study period was 99.5% (standard deviation, 0.5%). Conclusion. The findings of this qualitative analysis are positive for blood safety in Latin America, with an average accuracy of 99.5% among the participating laboratories and blood banks. This report reflects an important improvement in blood bank serological screening EQAP-PAHO report since the 2003.

RESUMEN Objetivo. Evaluar el tamizaje de muestras de sangre en las que se analizan marcadores de enfermedades infecciosas en laboratorios y bancos de sangre de América Latina según los resultados de un programa de evaluación externa de la calidad (EQAP, por su sigla en inglés). Métodos. Este análisis cualitativo utilizó datos del EQAP —coordinado por la Fundação Pro Sangue Hemocentro de São Paulo con el apoyo de la Organización Panamericana de la Salud— para evaluar la eficacia del tamizaje sanguíneo para la detección de enfermedades infecciosas que se realizó entre el 2014 y el 2018 en América Latina. Cada laboratorio o banco de sangre participante recibió un panel idéntico para análisis a ciegas compuesto por 24 muestras de sangre con reactividad variable para todos los parámetros del tamizaje. Los paneles se procesaron en cada establecimiento participante y los resultados se enviaron a la Fundação Pro Sangue Hemocentro de São Paulo donde se realizaron análisis individuales y conjuntos. Había dos tipos de resultados discrepantes que eran posibles fallas del tamizaje: los positivos falsos (PF) y los negativos falsos (NF). Resultados. En total se evaluaron 23 136 muestras. Las tasas generales de PF, NF y resultados concordantes fueron, respectivamente, del 0,3%, 1,0% y 98,7%. Se obtuvieron siete NF en casos de HBsAg (1,0%), 12 en casos de sífilis (2,6%) y 21 en casos de enfermedad de Chagas (2,9%). No se obtuvieron NF en casos de infección por virus del VIH, el VHC o el VLTH. La precisión promedio de todos los laboratorios y bancos de sangre participantes en el EQAP durante el periodo de estudio fue del 99,5% (desviación típica: 0,5%). Conclusión. Los resultados de este análisis cualitativo son positivos en lo referente a la seguridad sanguínea en América Latina, con una precisión promedio del 99,5% entre los laboratorios y bancos de sangre participantes. Este informe refleja la considerable mejora del tamizaje serológico que se realiza en los bancos de sangre, en comparación con los resultados del informe del EQAP que contó con el apoyo de la OPS y se publicó en el 2003.

RESUMO Objetivo. Avaliar a triagem de marcadores de doenças infecciosas em amostras de sangue realizada em laboratórios e bancos de sangue da América Latina de acordo com os resultados de um Programa Externo de Avaliação de Qualidade (EQAP, na sigla em inglês). Métodos. Esta análise qualitativa usou dados do EQAP coordenado pela Fundação Pró-Sangue Hemocentro de São Paulo, com o apoio da Organização Pan-Americana da Saúde, para avaliar o desempenho da triagem de sangue quanto a doenças infecciosas no período de 2014 a 2018 na América Latina. Cada laboratório ou banco de sangue participante recebeu um painel cego idêntico com 24 amostras de sangue de reatividade variável para todos os parâmetros de triagem. Os painéis foram processados em cada estabelecimento participante e os resultados foram devolvidos à Fundação Pró-Sangue Hemocentro de São Paulo para análises individuais e conjuntas. Dois tipos de resultados discrepantes representavam falhas em potencial: resultados falso-positivos e resultados falso-negativos (não reativos). Resultados. Foram avaliadas 23.136 amostras. As taxas globais de resultados falso-positivos, falso-negativos e concordantes foram de 0,3%, 1,0% e 98,7%, respectivamente. Foram encontrados sete resultados falso-negativos para HBsAg (1,0%), 12 para sífilis (2,6%) e 21 para doença de Chagas (2,9%). Não houve resultados falso-negativos para os vírus HIV, HCV e HTLV. A acurácia média de todos os laboratórios e bancos de sangue que participaram do EQAP durante o período do estudo foi de 99,5% (desvio padrão de 0,5%). Conclusões. Os resultados desta análise qualitativa são positivos para a segurança do sangue na América Latina, com uma acurácia média de 99,5% entre os laboratórios e bancos de sangue participantes. Este relatório reflete uma melhoria importante na triagem sorológica dos bancos de sangue em relação aos resultados do relatório do EQAP apoiado pela OPAS que foi publicado em 2003.

Measles, mumps and rubella vaccine 12 months after hematopoietic stem cell transplantation

ABSTRACT The measles, mumps and rubella (MMR) vaccine is usually recommended from 24 months after a hematopoietic stem cell transplant (HSCT). Some authors have demonstrated that the MMR vaccination can be safe from 12 months post-HSCT in non-immunosuppressed patients, as recommended by the Brazilian National Immunization Program/Ministry of Health, since 2006. The objectives of this study were to evaluate when patients received MMR vaccine after an HSCT in our care service and if there were reports of any side effects. We retrospectively reviewed the records of HSCT recipients who received at least one MMR dose in our care service, a quaternary teaching hospital in Sao Paulo city, Brazil, from 2017 to 2021. We identified 82 patients: 75.6% (90.1% in the autologous group and 45.1% in the allogeneic group) were vaccinated before 23 months post-transplantation. None reported side effects following the vaccination. Our data support that the MMR vaccination is safe from 12 to 23 months after HSCT.

Association between FY* 02N. 01 and the severity of COVID-19: initial observations

ABSTRACT Introduction The pro-inflammatory immune response underlies severe cases of COVID-19. Antigens of the Duffy blood group systems are receptors for pro-inflammation chemokines. The ACKR1 c.-67T>C gene variation silences the expression of Duffy antigens on erythrocytes and individuals presenting this variant in homozygosity have impaired inflammatory response control. Our aim was to evaluate the association between the ACKR1 c.-67T>C and the severity of COVID-19. Methods This was a retrospective single-center case-control study, enrolling 164 participants who were divided into four groups: 1) Death: COVID-19 patients who died during hospitalization; 2) Hospital Discharge: COVID-19 patients who were discharged for home after hospitalizations; 3) Convalescent Plasma Donors: COVID-19 patients who were not hospitalized, and; 4) Controls: patients with diagnosis other than COVID-19. Patients were genotyped for the ACKR1 c.-67T>C (FY*02 N.01 allele) and the frequency of individuals presenting the altered allele was compared between the groups. Results The groups significantly differed in terms of the percentage of patients presenting at least one FY*02N.01 allele: 36.8% (Death group), 37% (Hospital Discharge group), 16.1% (Convalescent Plasma group) and 16.2% (Control group) (p= 0.027). The self-declared race (p < 0.001) and the occurrence of in hospital death (p= 0.058) were independently associated with the presence of the FY*02N.01 allele. Hypertension (p < 0.001), age (p < 0.001) and the presence of at least one FY*02N.01 allele (p= 0.009) were independently associated with the need for hospitalization. Conclusion There is a suggestive association between the presence of the FY*02N.01 and the severity of COVID-19. This may be a mechanism underlying the worse prognosis for Afro-descendants infected with SARS-CoV-2.

Transfusion of ABO non-identical platelets increases the severity of trauma patients at ICU admission

ABSTRACT Background: Transfusion of ABO-compatible non-identical platelets (PTLs), fresh plasma (FP) and red blood cells (RBCs) has been associated with increased morbidity and mortality of recipients. Trauma victims are frequently exposed to ABO non-identical products, given the need for emergency transfusions. Our goal was to evaluate the impact of the transfusion of ABO non-identical blood products on the severity and all-cause 30-day mortality of trauma patients. Methods: This was a retrospective single-center cohort, which included trauma patients who received emergency transfusions in the first 24 h of hospitalization. Patients were divided in two groups according to the use of <3 or ≥3 ABO non-identical blood products. The patient severity, measured by the Acute Physiology and Chronic Health Evaluation (APACHEII) score at ICU admission, and the 30-day mortality were compared between groups. Results: Two hundred and sixteen trauma patients were enrolled. Of these, 21.3% received ≥3 ABO non-identical blood products (RBCs, PLTs and FP or cryoprecipitate). The transfusion of ≥3 ABO non-identical blood products in the first 24 h of hospitalization was independently associated with a higher APACHEII score at ICU admission (OR = 3.28 and CI95% = 1.48-7.16). Transfusion of at least one unit of ABO non-identical PTLs was also associated with severity (OR = 10.89 and CI95% = 3.38-38.49). Transfusion of ABO non-identical blood products was not associated with a higher 30-day mortality in the studied cohort. Conclusion: The transfusion of ABO non-identical blood products and, especially, of ABO non-identical PLTs may be associated with the greater severity of trauma patients at ICU admission. The transfusion of ABO non-identical blood products in the trauma setting is not without risks.

Validation of a formula predictive of peripheral blood stem cell yield and successful collection in healthy allogeneic donors

ABSTRACT Background: An efficient mobilization and collection of peripheral blood stem cells (PBSCs) are crucial to optimize engraftment in the recipient. We aim to validate a formula that predicted CD34+ cell yield and to describe variables that correlated with high yield mobilization and collection in healthy donors. Methods: We retrospectively analyzed clinical and laboratory data from healthy donors who underwent PBSC collection from 2006 to 2015. The predicted number of collected cells was calculated using the following formula: Total number of CD34+ (cells × 106/kg) yield = [(peripheral CD34+ cells/µL) × (0.43)/recipient body weight (kg)] × total liters processed. Results: We evaluated 338 collections from 307 allogeneic PBSC donors. The predicted versus the observed number of CD34+ cells/kg collected yielded an r-value of 0.775 (0.726-0.816; p < 0.0001). Overall, 55.7% donors had an acceptable mobilization level. Donors with a body weight <67 kg were less likely to yield a satisfactory CD34+ cell count (OR = 0.44; 95% CI 0.24-0.81), while a white blood cell (WBC) count >40 × 109/L (OR = 3.69; 2.11-6.46) and platelet count ≥200 × 109/L (OR = 2.09; 1.26-3.47) on the day of collection predicted a good level of mobilization. Predictors of a CD34+ cell yield/kg of ≥4 × 106 with only one apheresis session were: circulating CD34+ cells/µL >40 (OR = 16; 6.94-36.93), hemoglobin ≥14 g/dL (OR = 3.40; 1.53-7.57), WBC >40 × 109/L (OR = 4.61; 2.10-10.10) on the first collection day, and a positive delta weight between donor and recipient (OR = 3.10; 1.36-7.06). Conclusion: The formula for predicting CD34+ cell yield is accurate and suggests the optimal length of time for successful leukapheresis. Validation of the predictors of successful mobilization will help to further refine PBSC leukapheresis procedures.

Salvage treatment for refractory or relapsed acute myeloid leukemia: a 10-year single-center experience

OBJECTIVES: The outcomes of refractory and relapsed acute myeloid leukemia (AML) patients in developing countries are underreported, even though the similar classic regimens are widely used. METHODS: We conducted a retrospective comparison of "MEC" (mitoxantrone, etoposide, and cytarabine) and "FLAG-IDA" (fludarabine, cytarabine, idarubicin, and filgrastim) in adults with first relapse or refractory AML. RESULTS: In total, 60 patients were included, of which 28 patients received MEC and 32 received FLAG-IDA. A complete response (CR) rate of 48.3% was observed. Of the included patients, 16 (27%) died before undergoing bone marrow assessment. No statiscally significant difference in CR rate was found between the two protocols (p=0.447). The median survival in the total cohort was 4 months, with a 3-year overall survival (OS) rate of 9.7%. In a multivariable model including age, fms-like tyrosine kinase 3 (FLT3) status, and stem-cell transplantation (SCT), only the last two indicators remained significant: FLT3-ITD mutation (hazard ratio [HR]=4.6, p<0.001) and SCT (HR=0.43, p=0.01). CONCLUSION: In our analysis, there were no significant differences between the chosen regimens. High rates of early toxicity were found, emphasizing the role of supportive care and judicious selection of patients who are eligible for intensive salvage therapy in this setting. The FLT3-ITD mutation and SCT remained significant factors for survival in our study, in line with the results of previous studies.

Detection of HIV-1 infections in blood donors during the pre-seroconversion window period in São Paulo, Brazil

Abstract By decreasing the pre-seroconversion window period, nucleic acid testing (NAT) has improved the safety of blood products and reduced the risk of transfusion-transmitted infections. Between 2011 and 2017, NAT determinations for approximately 898,202 donations were performed at Fundação Pró-Sangue/Hemocentro de São Paulo (FPS-HSP). Three seronegative HIV-viremic donations were detected. The NAT yield rate per million donations was 3.34 for HIV, and the acute HIV-1 infections detected are described, followed by a brief review of the situation in Brazil.

Padrozação de estratégia molecular custo-efetiva para rastreamento de fenótipos eritrocitários e plaquetários raros em doadores de sangue visando à organização de banco de doadores raros no estado de São Paulo / Cost-effective molecular strategy standardization for screening of erythrocyte phenotypes and rare platelet in blood donors aiming at the organization of a rare donor bank in the state of São Paulo

OBJETIVOS: 1- Padronizar a genotipagem em larga escala para determinação de antígenos eritrocitários e plaquetários pela plataforma de OpenArray®em doadores de sangue. 2- Elaboração de software para registro destes doadores, com interface com o equipamento de genotipagem. METODOLOGIA: Extração automatizada de DNA e genotipagem através demicroarranjos líquidos (OpenArray®) para 32 alelos codificantes de antígenos eritrocitários e plaquetários. RESULTADOS: Foi realizada a genotipagem de 5487 doadores para os antígenos propostos, de forma completamente interfaceada e automatizada. O ensaio customizado de Open Array® mostrou-se acurado e de rápida execução. Elaborou-se software próprio para interfaceamento dos resultados da genotipagem e busca dos genótipos. CONCLUSÃO: Padronizou-se estratégia efetiva para rastreamento de doadores de sangue com fenótipos raros. A automação de todas as etapas experimentais e o interfaceamento completo dos dados minimizaram os erros humanos e aumentaram a rapidez do processo descrito, que pode ser aplicado como estratégia de genotipagem de doadores de todo o Estado de São Paulo.

Optimisation of a quantitative polymerase chain reaction-based strategy for the detection and quantification of human herpesvirus 6 DNA in patients undergoing allogeneic haematopoietic stem cell transplantation

Human herpesvirus 6 (HHV-6) may cause severe complications after haematopoietic stem cell transplantation (HSCT). Monitoring this virus and providing precise, rapid and early diagnosis of related clinical diseases, constitute essential measures to improve outcomes. A prospective survey on the incidence and clinical features of HHV-6 infections after HSCT has not yet been conducted in Brazilian patients and the impact of this infection on HSCT outcome remains unclear. A rapid test based on real-time quantitative polymerase chain reaction (qPCR) has been optimised to screen and quantify clinical samples for HHV-6. The detection step was based on reaction with TaqMan® hydrolysis probes. A set of previously described primers and probes have been tested to evaluate efficiency, sensitivity and reproducibility. The target efficiency range was 91.4% with linearity ranging from 10-106 copies/reaction and a limit of detection of five copies/reaction or 250 copies/mL of plasma. The qPCR assay developed in the present study was simple, rapid and sensitive, allowing the detection of a wide range of HHV-6 loads. In conclusion, this test may be useful as a practical tool to help elucidate the clinical relevance of HHV-6 infection and reactivation in different scenarios and to determine the need for surveillance.