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Before the advent of the influenza A(H1N1)pdm virus in 2009, the information available about the clinical manifestations and prognosis of influenza in immunosuppressed patients was scarce. With the 2009 pandemic, knowledge of the behavior, severity and importance of antiviral therapy for influenza A infection in immunocompromised hosts has increased considerably. The aim of the present manuscript is to review the main challenges of influenza in the most representative immunosuppressed populations such as solid organ transplant recipients, hematopoietic stem cell transplant recipients, patients with solid and hematological cancer and human immunodeficiency virus infected patients.

Background Valganciclovir preemptive therapy guided by the viral load is the current strategy recommended for preventing CMV disease in CMV-seropositive Solid Organ Transplant Recipients (SOTR) at lower risk for developing CMV infection. However, universal viral load cut-off has not been established for initiating therapy. Objectives Our goal was to define and validate a standardized cut-off determined in plasma by real-time PCR assay for initiating preemptive therapy in this population. Study design A prospective cohort study of consecutive cases of CMV-seropositive SOTR was carried out. The cut-off value was determined in a derivation cohort and was validated in the validation cohort. Viral loads were determined using the Quant CMV LightCycler 2.0 real-time PCR System (Roche Applied Science) and results were standardized using the WHO International Standard for human CMV. Results A viral load of 3983 IU/ml (2600 copies/ml) was established as the optimal cut-off for initiating preemptive therapy in a cohort of 141 patients with 982 tests and validated in a cohort of 252 recipients with a total of 2022 test. This cut-off had a 99.6% NPV indicating that the great majority of patients at lower risk will not develop CMV disease without specific antiviral therapy. The high sensitivity and specificity (89.9% and 88.9%, respectively) and the relatively small numbers of patients with CMV disease confirm that real-time PCR was optimal. Conclusions We have established a cut-off viral load for starting preemptive therapy for CMV-seropositive SOT recipients. Our results emphasized the importance of a mandatory follow-up protocol for CMV-seropositive patients receiving preemptive treatment.

BACKGROUND Little is known about the long-term antibody response to the 2009-H1N1 vaccine in solid organ transplant recipients (SOTR) and its clinical repercussion on the efficacy of following 2010-2011 influenza vaccine. METHODS We performed a multicenter prospective study in SOTR receiving one dose of the nonadjuvant 2010-2011 seasonal influenza vaccine and determined the immunological response at 5 weeks after vaccination. RESULTS One hundred SOTR were included. Long-term antibody titers to the previous vaccine were only detected in one third of the patients. Patients with baseline titers had significantly higher seroprotection for the 2009-H1N1 strain (100% vs. 73%, relative risks [RR] 1.37, 95% confidence intervals [CI] 1.19-1.57; P=0.006), for H3N2 strain (100% vs. 62.2%, RR 1.61, 95% CI 1.36-1.90; P=0.005), and for B strain (100% vs. 69%; P=0.02). The seroconversion rate in patients with baseline titers was 90.9% vs. 73% (RR 2.97, 95% CI 0.75-11.74; P=0.07) for the 2009-H1N1 strain, 92.2% vs. 62.2% (RR 5.29, 95% CI 0.8-35.7; P=0.02) for the H3N2 strain, and 58.3% vs. 69% (P=0.45) for the B strain. CONCLUSIONS SOTR response to the 2010-2011 influenza vaccine was not optimal. The response was related to baseline titers; however, most of the patients did not exhibit detectable antibodies at vaccination lacking long-term response. New strategies are necessary to improve vaccination efficacy.

Cytomegalovirus (CMV) end-organ disease is a serious complication after stem cell transplantation (SCT) (Boeckh M, 2003). Within the first one hundred days after SCT, 50% of recipients develop CMV infection determined by positive antigenemia and 65 to 86.5% when viral replication is determined by real-time PCR (RT-PCR) (Ljungman et al., 2006; Solano et al., 2001). Described risk factors for CMV infection concern donor type, graft source, positive CMV serostatus of donor and recipient, CD34+ graft selection, preconditioning regimen, GvHD prophylaxis regimen, incidence of acute and chronic GvHD and prophylaxis and treatment for GvHD (Ljungman et al., 2002; Ozdemir et al., 2007). Pre-emptive therapy is currently based on viral replication determined by either antigenemia or RT-PCR (Drew, 2007). Although antigenemia has been extensively used (Drew, 2007), RT-PCR has been shown to be more sensitive (Hakki et al., 2003; Solano et al., 2001).

A real-time PCR assay was developed for detecting the presence of Acinetobacter baumannii on hospital equipment and compared to conventional bacterial culture using 100 hospital environmental samples. The real-time PCR detected contaminated surfaces in 4 h with high sensitivity (100%) compared to conventional culture. Thirty-eight percent of samples were positive by real-time PCR and negative by bacterial culture (false positives), possibly indicating the widespread presence of bacterial DNA that is not associated with viable bacteria Copyright © 2012, American Society for Microbiology. All Rights Reserved., This work was supported by the Ministerio de Ciencia e Innovación, Instituto de Salud Carlos III - co-financed by European Development Regional Fund >A way to achieve Europe>, Spanish Network for Research in Infectious Pathology [REIPI RD06/0008/0000]. M.J.M. is supported by the Programme Juan de la Cierva from the Ministerio de Ciencia e Innovación of Spain. P.P.-R. is supported by the Instituto de Salud Carlos III, Programme Miguel Servet CP05/00226.

Objectives: After the last pandemic the knowledge regarding influenza A infection has improved however, the outcomes of influenza B infection remain poorly studied. The aim of this study was to compare the features of influenza B versus influenza A(H1N1)pdm09 infections during the 2010-2011 epidemic-season., Methods: A prospective, observational-cohort of adults with laboratory-confirmed influenza infection during the 2010-2011 epidemic-season was studied., Results: Fifty cases of influenza B and 80 of influenza A(H1N1)pdm09 infection were enrolled. Among patients with influenza B, the median age was 34 years-old (23-64), 30% pregnant, 24% obese, 34% transplant recipients and 14% with bacterial co-infection. Twenty-eight percent of patients had pneumonia with alveolar localized pattern and five (10%) died. Pneumonia was associated with delayed antiviral therapy, older age, higher Charlson score, invasive mechanical ventilation and bacterial co-infection. Obesity and pregnancy were not associated with complicated influenza B infection. The proportion of pneumonia, admission to the ICU and mortality did not differ between cases of influenza A(H1N1)pdm09 and influenza B infection., Conclusions: Influenza B infection causes severe infection and it is associated with pneumonia or death, similar to influenza A(H1N1)pdm09 infection. Rapid diagnosis and early antiviral therapy are necessary for managing influenza pneumonia during epidemic periods. © 2012 The British Infection Association., This work was supported by the Ministerio de Ciencia e Innovación, Instituto de Salud Carlos III (GR09/0041) and - co-financed by European Development Regional Fund >A way to achieve Europe> ERDF, Spanish Network for the Research in Infectious Diseases (REIPI RD06/0008). P.P-R. was funded by Instituto de Salud Carlos III, Programme Miguel Servet (CP05/00226).

Cordero, E. et al., Concern has been raised regarding the response to vaccination in solid organ transplant recipients (SOTR) undergoing immunosuppressant regimens and the possibility of rejection related to the immune response associated with pandemic influenza H1N1–2009 vaccination. The goal of this study was to assess the immunogenicity, efficacy and safety of the pandemic vaccine in SOTR.We performed a multicenter prospective study in SOTR receiving the pandemic vaccine. Immunological response was determined in serum 5 weeks after vaccination by microneutralization assays, and immunoglobulins were measured by ELISA. Three hundred and forty-six SOTR were included. Preexisting seroprotection was detected in 13.6% of cases and rates of seroconversion and seroprotection after vaccination were 73.1% and 82.9%, respectively. Patients with baseline antibody titers had better geometric mean titers (GMT)-post after pandemic vaccination (339.4 vs. 121.4, p < 0.001). Younger age, liver disease andm-TOR inhibitor therapywere independently associated with lower seroprotection and GMT-post. There were no major adverse effects or rejection episodes. Pandemic vaccine was safe in SOTR and elicited an adequate response, although lower than in healthy individuals. This is the first study describing a decreased response after vaccination in patients receiving mTOR inhibitors who presented lower seroprotection rates and lower GMT-post., This work was supported by the Fondo de Investigación Sanitaria (PI050226/2005 and PI060521/2006);Ministerio de Ciencia e Innovación, Instituto de Salud Carlos III (GR09/0041) and Ministerio de Ciencia e Innovación, Instituto de Salud Carlos III – cofinanced by European Development Regional Fund "A way to achieve Europe" ERDF, SpanishNetwork for the Research in Infectious Diseases (REIPI RD06/0008/0000).

Background Most of the non-B HIV-1 subtypes are predominant in Sub-Saharan Africa and India although they have been found worldwide. In the last decade, immigration from these areas has increased considerably in Spain. The objective of this study was to evaluate the prevalence of non-B subtypes circulating in a cohort of HIV-1-infected immigrants in Seville, Southern Spain and to identify drug resistance-associated mutations. Methods Complete protease and first 220 codons of the reverse transcriptase coding regions were amplified and sequenced by population sequencing. HIV-1 subtypes were determined using Stanford University Drug Resistance Database, and phylogenetic analysis was performed comparing multiple reported sequences. Drug resistance mutations were defined according to the International AIDS Society-USA. Results From 2000 to 2010 a total of 1,089 newly diagnosed HIV-1-infected patients were enrolled in our cohort. Of these, 121 were immigrants, of which 98 had ethical approval and informed consent to include in our study. Twenty-nine immigrants (29/98, 29.6%) were infected with non-B subtypes, of which 15/29 (51.7%) were CRF02-AG, mostly from Sub-Saharan Africa, and 2/29 (6.9%) were CRF01-AE from Eastern Europe. A, C, F, J and G subtypes from Eastern Europe, Central-South America and Sub-Saharan Africa were also present. Some others harboured recombinant forms CRF02-AG/CRF01-AE, CRF2-AG/G and F/B, B/C, and K/G, in PR and RT-coding regions. Patients infected with non-B subtypes showed a high frequency of minor protease inhibitor resistance mutations, M36I, L63P, and K20R/I. Only one patient, CRF02_AG, showed major resistance mutation L90M. Major RT inhibitor resistance mutations K70R and A98G were present in one patient with subtype G, L100I in one patient with CRF01_AE, and K103N in another patient with CRF01_AE. Three patients had other mutations such as V118I, E138A and V90I. Conclusions The circulation of non-B subtypes has significantly increased in Southern Spain during the last decade, with 29.6% prevalence, in association with demographic changes among immigrants. This could be an issue in the treatment and management of these patients. Resistance mutations have been detected in these patients with a prevalence of 7% among treatment-naïve patients compared with the 21% detected among patients under HAART or during treatment interruption.

B cell responses to minor histocompatibility antigens (mHags) have not been extensively studied after allogeneic hematopoietic stem cell transplantation (HSCT). Glutathione S-transferase T1 (GSTT1) is a drug metabolizing enzyme encoded by a single gene that is highly expressed in liver and kidney. Anti-GSTT1 antibodies have been described in the context of antibody-mediated rejection in kidney and liver transplantation, due to a mismatch between donor and recipient. The aim of the present study was to investigate the specific immune response against GSTT1 in HSCT with production of antibodies and their influence in the development of hepatic graft-versus-host-disease (GVHD). Forty patients and their respective donors were included in the study. The median follow-up time was 35.6. months (range 0.6-76. months) and a total of 349 serum samples were tested for the presence of anti-GSTT1 antibodies by ELISA test. Statistical analysis was performed by defining the GSTT1 null donor/positive recipient as mismatch compared with the other three genetic combinations regarded as GSTT1-matched. Antibodies were found in three patients within the group of null donor/positive recipient and one within the null/null group. Development of liver GVHD, particularly its acute form, was highly associated with the GSTT1-mismatch (P=0.0178) and with the presence of post-transplant anti-GSTT1 antibodies (P=0.0076). We conclude that GSTT1 could be considered as a new mHag in hepatic GVHD. The fact that three donors were parous females and the rapid production of antibodies after HSCT suggests the existence in the graft of memory B-cells specific for the GSTT1 antigen. © 2011 Elsevier B.V., This work was supported by grants from the Ministry of Education and Science of Spain (05/0733, 05/0374) and grants from Junta de Andalucia, Spain (PI-0332/2007, P07-CTS-02886). The work carried out at our laboratory, received support from the European Community through the regional development funding program (FEDER).

This work was supported by the Ministerio de Ciencia e Innovación, Instituto de Salud Carlos III, cofinanced by European Development Regional Fund “A Way To Achieve Europe,” Spanish Network for Research in Infectious Pathology (REIPI RD06/0008/0000). M.J.M. is supported by the Programme Juan de la Cierva from the Ministerio de Ciencia e Innovación of Spain. P.P.-R. is supported by the Instituto de Salud Carlos III, Programme Miguel Servet CP05/00226.

Optimizing treatment for patients with persistent low-level viremia is complicated because most genotyping tests are validated for viral loads >1000 copies per milliliter. In this study, genotypes of 92 treatment-experienced patients with persistent low-level viremia were determined using an in-house assay. Based on the resistance profiles obtained from genotyping and patient pharmacologic history, patients were either maintained on their antiviral regimen (n = 51) or received an optimized regimen (n = 41). In the group receiving optimized treatment, undetectable viral loads were achieved in 73.2% at 6 months and at 90.2% at 1 year, indicating that treatment guided by genotyping of patients with low-level viremia is effective in achieving viral suppression.

The effect of minor mutations in PR on treatment outcome has not been well established. We characterized the HIV protease minor mutations, L10I, compared to the minor mutation, L63P, and the major mutation D30N and their impact on viral fitness and resistance to protease inhibitors. Mutations were introduced individually and in combination by site-directed mutagenesis into the provirus pNL4.3ren and constructs used for replication capacity (RC) and resistance assays. A structure prediction of the protease carrying the L10I mutation was determined. The prevalence of the minor mutation L10I had a pattern similar to that found for major mutations D30N, with a low prevalence (4.9%) in naive patients and significantly higher prevalence in treated patients. Furthermore, viruses carrying the major mutation D30N or the minor mutation L10I showed a significant decrease in RC (p-value, This work was supported by Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica (IþDþI) PI05/0226, Instituto de Salud "Carlos III"-Fondo de Investigación Sanitaria, Ministerio de Ciencia e Innovación; Consejería de Innovación, Ciencia y Empresa P06-CTS-01915, Junta de Andalucía; and Red de Investigación en SIDA (ISCIII RD06/0006), Ministerio de Ciencia e Innovación.

Fifty percent of allogeneic stem cell recipients develop cytomegalovirus (CMV) infection in the first 100 days posttransplantation. Various methods have been used to determine CMV infections, including antigenemia assay and real-time polymerase chain reaction (RT-PCR). Although antigenemia assay has been used more frequently, this technique is less sensitive than RT-PCR. In contrast, RT-PCR has a low positive predictive value for CMV end-organ disease. Cytomegalovirus infections were analyzed in 41 peripheral blood samples from allogeneic stem cell recipients using both antigenemia assay and RT-PCR; results were discordant in 36.6% of patients. Although the antigenemia assay detected CMV replication in 29.2% of cases, RT-PCR was positive in 65.8%. In 83.3% of patients, results detected using the antigenemia assay were delayed by a median (range) of 5 (2–20) weeks compared with positive RT-PCR results. Within the first 100 days posttransplantation, higher levels of viral replication measured using RT-PCR were observed in patients with vs without antigenemia. In addition, in patients with antigenemia, viral load was significantly higher before day 100 than after ( P = .01 and P = .008, respectively) compared with those without antigenemia.

5 páginas, 3 figuras., Background Quantitative detection of cytomegalovirus (CMV) DNAemia by real-time PCR is currently the primary choice for the surveillance of active CMV infection in allogeneic stem cell transplant (Allo-SCT) recipients. Nevertheless, no universally accepted standards for CMV viral load quantitation are available, this being critical when clinical studies involving various participant centers that use different assays are planned. Objective To compare the analytical performance of two commercially-available real-time PCR assays carried out at two different centers. Study design Plasma samples were collected at the University Hospital Virgen del Rocío (A) and at the Hospital Clínico Universitario (B) and were exchanged for analysis. In hospital A, DNA was extracted manually and viral loads were quantitated with the Affigene CMV Trender. In hospital B, DNA extractions were performed using an automated system and viral loads were quantitated using the CMV PCR Kit manufactured for Abbott by Qiagen. Results A total of 80 samples obtained from Allo-SCT recipients (20 samples per each of the following CMV DNA load groups: undetectable level, 10,000 copies/mL) were analyzed. The Affigene CMV Trender assay yielded significantly higher viral loads than the Abbott CMV real-time PCR Kit, regardless of the DNA extraction method employed. Conclusions Automated DNA extraction systems should be thoroughly evaluated for their analytical performance. Local guidelines for the initiation of pre-emptive therapy based on commercial real-time PCR assays measurements must be established as long as universally accepted standards for quantitative analysis of CMV DNAemia are not available., This study was supported by the Instituto de Salud Carlos III-Fondo de Investigación Sanitaria (060521/2006, 080910/2008 and 081137), Consejería de Innovación, Ciencia y Empresa, Junta de Andalucía P08-CTS-03649 and Ministerio de Sanidad y Consumo, Instituto de Salud Carlos III – FEDER, Spanish Network for the Research in Infectious Diseases (REIPI RD06/0008) and Spanish Network for the Research in Cancer (RTICC RD06/0020/0012). I.G.A. was funded by Instituto de Salud Carlos III, post-FSE CM07/00061.

Actin is a cytoskeletal protein that is ubiquitous in eukaryotes, hence the corresponding genes and proteins have been isolated from numerous organisms as different as animals, plants, fungi and protozoa. Several atomic models are available for the monomeric as well as the filamentous form, and more than 70 proteins that bind actin and control filament dynamics have been isolated from diverse eukaryotes. Moreover, the function and dynamics of the actin cytoskeleton in several eukaryotic systems have been depicted in depth. Unlike other protozoa, such as amoeba, actin is not an abundant protein in ciliates, whose cytoskeleton is mainly composed of microtubular arrays. Ciliate actin has been studied in several species, and it was established early on that this ciliate protein is very different from that of other eukaryotes. Similarly, the actin-binding proteins studied in ciliates display great differences with those of other eukaryotes. Consequently, ciliate actin has been considered as "unconventional," and this review focuses on molecular data leading to this conclusion. Dirección General de Investigación Científica y Técnica (DGICYT) PB97-0710-C02-01

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Cytomegalovirus (CMV) end-organ disease is a serious, frequent complication after allogenic stem cell transplantation (Allo-SCT). There are two prevention strategies: universal prophylaxis and preemptive therapy. Preemptive therapy is administered based on the results of sensitive techniques that detect the viral infection. We analyzed 41 peripheral blood Allo-SCT recipients: 34 received prophylaxis and seven preemptive treatment. Viral infections determined using real-time polymerase chain reaction (RT-PCR) assays occurred at an overall incidence of 65.8%. The viral loads quantified by RT-PCR were compared among the prophylaxis versus the preemptive group. Overall, the median viral load was significantly higher in the preemptive compared with the prophlylaxis group (P = .002). Furthermore, within the first 100 days posttransplantation, viral load values were higher among patients undergoing preemptive therapy (P = .009).

Solid organ transplant (SOT) recipients are at greater risk than the general population for complications and mortality from influenza infection.Researchers and clinicians with experience in SOT infections have developed this consensus document in collaboration with several Spanish scientific societies and study networks related to transplant management. We conducted a systematic review to assess the management and prevention of influenza infection in SOT recipients. Evidence levels based on the available literature are given for each recommendation. This article was written in accordance with international recommendations on consensus statements and the recommendations of the Appraisal of Guidelines for Research and Evaluation II (AGREE II).Recommendations are provided on the procurement of organs from donors with suspected or confirmed influenza infection. We highlight the importance of the possibility of influenza infection in any SOT recipient presenting upper or lower respiratory symptoms, including pneumonia. The importance of early antiviral treatment of SOT recipients with suspected or confirmed influenza infection and the necessity of annual influenza vaccination are emphasized. The microbiological techniques for diagnosis of influenza infection are reviewed. Guidelines for the use of antiviral prophylaxis in inpatients and outpatients are provided. Recommendations for household contacts of SOT recipients with influenza infection and health care workers in close contact with transplant patients are also included. Finally antiviral dose adjustment guidelines are presented for cases of impaired renal function and for pediatric populations.The latest scientific information available regarding influenza infection in the context of SOT is incorporated into this document.

Abstract 1281 Background: Cytomegalovirus (CMV) end-organ disease is a serious complication after allogeneic stem cell transplantation (Allo-SCT). The quality of the post-transplant immune reconstitution plays a crucial role in the development of both, post-transplant infections and relapse of the underlying disease, two of the main factors conditioning post-transplant mortality and hence final survival. The relationship between viral replication and CMV specific immune reconstitution has not been completely unveiled. This knowledge would allow identifying patients at risk for developing CMV disease and eventually improving their clinical management. Objectives: to analyze the relationship between CMV replication and specific CMV immune reconstitution and the potential influence of this relationship in main clinical outcomes. Patients and Methods: A prospective study of consecutive recipients of Allo-SCT was performed from June 2008 through December 2009 at a single institution. Blood samples were collected from one week before transplant, weekly during the first three months after transplant, every other week from month three to six and monthly from month seven to complete one year of follow up. CMV viral load was determined by real time PCR and CMV-specific T cell response was determined by flow cytometry with surface markers and intracellular cytokine staining. The percentage of activated CD4+, CD8+ and CD3+ T cells expressing CD69 were considered positive when IFN-’Y cytokine secretion was over 0.25%. Chimerism of the isolated CD8+ T cell subpopulation was determined by PCR. CD69 expression and cytokine secretion were compared in both CD4+ and CD8+ T cells between the different time points and both subsets of patients by the Wilcoxon test. CMV viral load reduction without treatment administration was compared by Wilcoxon test. Differences were considered statistically significant for p-values < 0.05. All statistical analyses were performed using SPSS 16.0 software (Chicago, IL). Results: Twenty-six patients were enrolled in the study with a median age of 33 years (range:15-61). We identified two groups of patients. A first group of 18 (69.2%) patients developed CMV infection and acquired CMV-specific T cell response by median week 8 (range:1-22; Figure 1A). The decline in the incidence of CMV replication episodes correlated with the acquisition of CMV-specific T cell response (Linear regresion r2=0.781, Pearson correlation p=0.01). A second group of 8 patients (30.8%) never developed CMV infection after the transplant, with a median value of 2 weeks (range:1-7; Figure 1B). The time of the acquisition of CMV-specific T cell response for the group with viremia and for the non-viremic group (week 2 vs. week 8) was statistically different (p= 0.01). Fifteen per cent of the patients (n=4) developed end-organ disease. Three out of five patients with end-organ disease developed replication CMV episodes over 10,000 copies/ml, while only 1 out of 13 patients with no end-organ disease developed viral loads under 10,000 copies/ml (p=0.04). The percentage of positive CD8+ T cells expressing IFN-γ in the patients that developed disease tended to be lower than in the patients that did not develop disease (median percentage of IFN-g positive CD8 T cells 0.3 vs. 0.5, respectively). The chimerism of the CD8+ T cells subpopulation after acquiring the specific immune response was of complete donor origin for all the patients. Conclusions: Developing donor-derived T-cell mediated CMV-specific immune response within the following two weeks after the transplant is inversely associated with the development CMV infection. The level of CMV viral load may predict end-organ disease. The use of a tool to determine T-cell mediated CMV-specific immune response in the clinical practice may help to improve the management of these patients, avoiding unnecessary treatments, and predicting clinical outcomes. Disclosures: No relevant conflicts of interest to declare.

Abstract 4539 BACKGROUND: Cytomegalovirus (CMV) end-organ disease is a serious complication after allogeneic stem cell transplantation (Allo-SCT). Described risk factors for CMV infection are pretransplant CMV seropositive status of the recipient, non related donor or umbilical cord transplant, depleted lymphocyte graft, high intensity conditioning regimen, severe graft versus host disease (GVHD), CD34+ selection of the graft and delayed CMV specific immune reconstitution. OBJETIVES: To identify different profiles of allogeneic stem cell recipients based on their previously described risk factors for CMV infection and its association with their clinical outcomes. PATIENTS AND METHODS: A prospective study of consecutive recipients of Allo-SCT was performed from June 2008 through December 2009 at a single institution. Patients were sequentially monitored both clinically and analytically. CMV viral load was determined by real time PCR and CMV-specific T cell response was determined by flow cytometry. Non-normal distribution data were expressed as median values (range). Chi-square test or Fisher exact test were used to compare differences between groups of categorical data. Differences were considered statistically significant for p-values < 0.05. All statistical analyses were performed using SPSS 16.0 software (Chicago, IL). RESULTS: Twenty-six patients were included with a median age of 33 years (range:15-61). The donor was an identical sibling in 42.3%, unrelated donor in 53.8% and a mismatched family member in 3.8%. The source was peripheral blood 76.9%, cord blood 15.4% and bone marrow in 7.7%. Previous positive serostatus for CMV was 76.9% in recipients, and 53.8% in donors. The conditioning regimen was myeloablative in 57.7% and reduced-intensity in 42.3%. Graf versus host disease (GvHD) prophylaxis was cyclosporine (CsA) plus methotrexate (MTX) in 57.7% and CsA plus mycophenolate mofetil (MMF) in 42.3%. The incidence of acute GvHD was 76.9% and chronic GvHD was 53.8%. Treatment of GVHD was steroids plus CsA or tacrolimus and/or MMF in 76.9% of acute and 46.2% of chronic GvHD. Previously described risk factors for developing CMV infection were compared between patients developing (n=18) and non-developing (n=8) CMV infection. A higher risk for developing CMV infection was associated with previous CMV positive serostatus of the recipient (84% in viremic patients vs. 16% in non-viremic patients; p=0.01) and CsA plus MMF as GvHD prophylaxis (90.9% vs. 9.1%; p=0.04). We analyzed whether having several risk factors for developing CMV infection has an effect on the risk for developing CMV replication after the transplant. Patients that presented four or more risk factors, developed viral replication more frequently than patients having less than four risk factors (91.6% vs. 8.3%; p=0.02). Patients who acquired an earlier specific CMV immune reconstitution did not developed CMV replication, opposite to those with later immune reconstitution (week 2 vs. week 8, p= 0.01). Overall survival at one year was of 44.4% in the group with viral replication, and 100% in the group with no viral replication, p=0.014 (Figure 1). CONCLUSIONS: Patients that did not developed episodes of CMV replication after the transplant presented less than four risk factors for developing CMV infection, developed an early T-cell mediated CMV immune response and had better overall survival. The development of CMV specific immunity able to control CMV replication may be considered as a paradigm of post-transplant immune reconstitution with potential influence on overall survival. Disclosures: No relevant conflicts of interest to declare.

INTRODUCTION: More than 50 % of alo-HSCT recipients develop CMV infection. The best technique for early detection of viral replication has not already been defined. Antigenaemia is the most used technique but it presents limitations. Quantitative RT-PCR could be more sensitive but contradictory information exists on clinical utility. OBJECTIVES: To compare clinical utility of RT-PCR and pp65 antigenaemia by systematic determination of CMV viral replication after alo-HSCT. PATIENTS, MATERIAL AND METHODS: Twenty one consecutive adult recipients of a peripheral blood alo-HSCT entered the study. Median age was 42 years (18–58) and ten (47.5%) were male. Twenty patients (95%) received a graft from an HLA related donor and one from an unrelated donor. Conditioning was mieloablative in thirteen cases (62 %) and every patient received GVHD prophylaxis with CsA/MTX. Thirteen (62%) received CMV prophylaxis (ganciclovir 300 mg/24h for 3 days/week until day +100) while eight (38 %) received antigenaemia-guided pre-emptive therapy (ganciclovir 5mg/kg/12h for 14 days). CMV viral load by RT-PCR and antigenaemia expression were determined periodically after transplant in all patients for a 6 months follow-up period. Antigenaemia was carried out by immunofluorescence on leukocytes with the anti-pp65 monoclonal antibody. Viral DNA was isolated in plasma by RT-PCR and used as a mold for RT-PCR amplification. Then it was quantified by competitive amplification of the DNA of the sample against an internal standard. RESULTS: CMV+ patients: Thirteen cases (62 %) showed viral replication determined by RT-PCR (n=12, 55 %), antigenaemia (n=8, 43 %), or both (n=7, 54%). Median replication occurred at week +8 (range 1–21). Two cases (9.5 %) developed CMV disease, showing viral replication targeted by both methods. Seven out of 13 cases (54%) showed viral replication by both methods. RT-PCR positivity preceded antigenaemia in 6 cases (86%). RT-PCR became positive in the first week postransplant in 4 cases, and in the weeks +2 and +3 in the other 2 cases. After treatment antigenaemia became negative in all the patients. RT-PCR persisted positive in 2 cases (in one of them antigenaemia reactivated later) while in the rest evolved towards negativity. Five cases (38.5%) showed CMV replication only identified by the RT-PCR test (PCR+/Ag−). Two of them were receiving prophylaxis. Number of DNA viral copies was not statistically different between the PCR+/Ag− and the PCR+/Ag+ patients. One case was RT-PCR negative and antigenaemia positive in just one determination evolving to negativity after treatment. CMV− patients: Eight cases (40%) did not present viral replication (PCR−/Ag−). All of them received viral prophylaxis. CONCLUSIONS: Prophylaxis against CMV reduced the rate of viral replication in the alo-HSCT setting. The technique of RT-PCR is more sensitive and preceded antigenaemia. RT-PCR identifies a group of patients, not detected by antigenaemia, with a low level of viral replication that do not develop CMV disease.

A macronuclear gene-sized molecule carrying an actin gene from the hypotrich ciliate, Histriculus cavicola, was characterized. Southern blot analysis using a coding region probe suggested that actin in H. cavicola is encoded by a single gene. A comparison of the promoter regions indicated that the H. cavicola actin gene has a TATA box in the 5' flanking region in a position identical to those in other oxytrich ciliates. The coding sequence of this gene is not interrupted by any introns, and codes for a protein of 375 amino acid residues. This protein shares a high degree of similarity with other oxytrichid actins, and a relatively low similarity with actins from other eukaryotes. Comparative analyses of sequences indicated that most of the amino acid substitutions in hypotrich actins are found in surface loops, while the core structures are well-conserved. The sites that interact with DNase I and several regions involved in actin-actin contact have diverged considerably in hypotrich actins, while nucleotide-binding sites are the best-conserved interaction motif.