Multicenter evaluation of PCR methods for detecting CMV DNA in blood donors

The Human Cytomegalovirus β2.7 Long Non-Coding RNA Prevents Induction of Reactive Oxygen Species to Maintain Viral Gene Silencing during Latency

Human cytomegalovirus (HCMV) is a significant source of disease for the immunosuppressed and immunonaive. The treatment of HCMV is made more problematic by viral latency, a lifecycle stage in which the virus reduces its own gene expression and produces no infectious virus. The most highly expressed viral gene during HCMV latency is the viral β2.7 long non-coding RNA. Although we have recently shown that the β2.7 lncRNA lowers levels of reactive oxygen species (ROS) during infection in monocytes, how this impacts latency is unclear. We now show that β2.7 is important for establishing and maintaining HCMV latency by aiding the suppression of viral lytic gene expression and that this is directly related to its ability to quench reactive oxygen species (ROS). Consistent with this, we also find that exogenous inducers of ROS cause reactivation of latent HCMV. These effects can be compensated by treatment with an antioxidant to lower ROS levels. Finally, we show that ROS-mediated reactivation is independent of myeloid differentiation, but instead relies on NF-κB activation. Altogether, these results reveal a novel factor that is central to the complex process that underpins HCMV latency. These findings may be of particular relevance in the transplant setting, in which transplanted tissue/organs are subject to very high ROS levels, and HCMV reactivation poses a significant threat.

Latent Cytomegalovirus-Driven Recruitment of Activated CD4+ T Cells Promotes Virus Reactivation

Human cytomegalovirus (HCMV) infection is not cleared by the initial immune response but persists for the lifetime of the host, in part due to its ability to establish a latent infection in cells of the myeloid lineage. HCMV has been shown to manipulate the secretion of cellular proteins during both lytic and latent infection; with changes caused by latent infection mainly investigated in CD34+ progenitor cells. Whilst CD34+ cells are generally bone marrow resident, their derivative CD14+ monocytes migrate to the periphery where they briefly circulate until extravasation into tissue sites. We have analyzed the effect of HCMV latent infection on the secretome of CD14+ monocytes, identifying an upregulation of both CCL8 and CXCL10 chemokines in the CD14+ latency-associated secretome. Unlike CD34+ cells, the CD14+ latency-associated secretome did not induce migration of resting immune cell subsets but did induce migration of activated NK and T cells expressing CXCR3 in a CXCL10 dependent manner. As reported in CD34+ latent infection, the CD14+ latency-associated secretome also suppressed the anti-viral activity of stimulated CD4+ T cells. Surprisingly, however, co-culture of activated autologous CD4+ T cells with latently infected monocytes resulted in reactivation of HCMV at levels comparable to those observed using M-CSF and IL-1β cytokines. We propose that these events represent a potential strategy to enable HCMV reactivation and local dissemination of the virus at peripheral tissue sites.

Profiling the Blood Compartment of Hematopoietic Stem Cell Transplant Patients During Human Cytomegalovirus Reactivation

Human cytomegalovirus (HCMV) is a widespread pathogen establishing a latent infection in its host. HCMV reactivation is a major health burden in immunocompromised individuals, and is a major cause of morbidity and mortality following hematopoietic stem cell transplantation (HSCT). Here we determined HCMV genomic levels using droplet digital PCR in different peripheral blood mononuclear cell (PBMC) populations in HCMV reactivating HSCT patients. This high sensitivity approach revealed that all PBMC populations harbored extremely low levels of viral DNA at the peak of HCMV DNAemia. Transcriptomic analysis of PBMCs from high-DNAemia samples revealed elevated expression of genes typical of HCMV specific T cells, while regulatory T cell enhancers as well as additional genes related to immune response were downregulated. Viral transcript levels in these samples were extremely low, but remarkably, the detected transcripts were mainly immediate early viral genes. Overall, our data indicate that HCMV DNAemia is associated with distinct signatures of immune response in the blood compartment, however it is not necessarily accompanied by substantial infection of PBMCs and the residual infected PBMCs are not productively infected.

Single cell analysis reveals human cytomegalovirus drives latently infected cells towards an anergic-like monocyte state

Human cytomegalovirus (HCMV) causes a lifelong infection through establishment of latency. Although reactivation from latency can cause life-threatening disease, our molecular understanding of HCMV latency is incomplete. Here we use single cell RNA-seq analysis to characterize latency in monocytes and hematopoietic stem and progenitor cells (HSPCs). In monocytes, we identify host cell surface markers that enable enrichment of latent cells harboring higher viral transcript levels, which can reactivate more efficiently, and are characterized by reduced intrinsic immune response that is important for viral gene expression. Significantly, in latent HSPCs, viral transcripts could be detected only in monocyte progenitors and were also associated with reduced immune-response. Overall, our work indicates that regardless of the developmental stage in which HCMV infects, HCMV drives hematopoietic cells towards a weaker immune-responsive monocyte state and that this anergic-like state is crucial for the virus ability to express its transcripts and to eventually reactivate.

Latent Cytomegalovirus (CMV) Infection Does Not Detrimentally Alter T Cell Responses in the Healthy Old, But Increased Latent CMV Carriage Is Related to Expanded CMV-Specific T Cells

Human cytomegalovirus (HCMV) primary infection and periodic reactivation of latent virus is generally well controlled by T-cell responses in healthy people. In older donors, overt HCMV disease is not generally seen despite the association of HCMV infection with increased risk of mortality. However, increases in HCMV DNA in urine of older people suggest that, although the immune response retains functionality, immunomodulation of the immune response due to lifelong viral carriage may alter its efficacy. Viral transcription is limited during latency to a handful of viral genes and there is both an IFNγ and cellular IL-10 CD4⁺ T-cell response to HCMV latency-associated proteins. Production of cIL-10 by HCMV-specific CD4⁺ T-cells is a candidate for aging-related immunomodulation. To address whether long-term carriage of HCMV changes the balance of cIL-10 and IFNγ-secreting T-cell populations, we recruited a large donor cohort aged 23–78 years and correlated T-cell responses to 11 HCMV proteins with age, HCMV IgG levels, latent HCMV load in CD14⁺ monocytes, and T-cell numbers in the blood. IFNγ responses by CD4⁺ and CD8⁺ T-cells to all HCMV proteins were detected, with no age-related increase in this cohort. IL-10-secreting CD4⁺ T cell responses were predominant to latency-associated proteins but did not increase with age. Quantification of HCMV genomes in CD14⁺ monocytes, a known site of latent HCMV carriage, did not reveal any increase in viral genome copies in older donors. Importantly, there was a significant positive correlation between the latent viral genome copy number and the breadth and magnitude of the IFNγ T-cell response to HCMV proteins. This study suggests in healthy aged donors that HCMV-specific changes in the T cell compartment were not affected by age and were effective, as viremia was a very rare event. Evidence from studies of unwell aged has shown HCMV to be an important comorbidity factor, surveillance of latent HCMV load and low-level viremia in blood and body fluids, alongside typical immunological measures and assessment of the antiviral capacity of the HCMV-specific immune cell function would be informative in determining if antiviral treatment of HCMV replication in the old maybe beneficial.

Transfusion-transmitted CMV infection - current knowledge and future perspectives

Transmission of human cytomegalovirus (CMV) via transfusion (TT-CMV) may still occur and remains a challenge in the treatment of immunocompromised CMV-seronegative patients, e.g. after stem cell transplantation, and for low birthweight infants. Measures to reduce the risk of TT-CMV have been evaluated in clinical studies, including leucocyte depletion of cellular blood products and/or the selection of CMV-IgG-negative donations. Studies in large blood donor cohorts indicate that donations from newly CMV-IgG-positive donors should bear the highest risk for transmitting CMV infections because they contain the highest levels of CMV-DNA, and early CMV antibodies cannot neutralise CMV. Based on this knowledge, rational strategies to reduce the residual risk of TT-CMV using leucoreduced blood products could be designed. However, there is a lack of evidence that CMV is still transmitted by transfusion of leucoreduced units. In low birthweight infants, most (if not all) CMV infections are caused by breast milk feeding or congenital transmission rather than by transfusion of leucoreduced blood products. For other patients at risk, no definitive data exist about the relative importance of alternative transmission routes of CMV compared to blood transfusion. As a result, only the conduction of well-designed studies addressing strategies to prevent TT-CMV and the thorough examination of presumed cases of TT-CMV will achieve guidance for the best transfusion regimen in patients at risk.

Human cytomegalovirus reactivation from latency: validation of a "switch" model in vitro

Background

Human cytomegalovirus (HCMV) is an opportunistic pathogen leading to severe and even fatal diseases in ‘at-risk’ categories of individuals upon primary infection or the symptomatic reactivation of the endogenous virus. The mechanisms which make the virus able to reactivate from latency are still matter of intense study. However, the very low number of peripheral blood monocytes (an important latent virus reservoir) harbouring HCMV DNA makes it very difficult to obtain adequate viral quantities to use in such studies.

Thus, the aim of the present study was to demonstrate the usefulness of human THP-1 monocytes, mostly employed as HCMV latent or lytic infection system, as a reactivation model.

Methods

THP-1 monocytes were infected with HCMV TB40E strain (latency model) at multiplicities of infection (MOI) of 0.5, 0.25 or 0.125. After infection, THP-1 aliquots were differentiated into macrophages (reactivation model). Infections were carried out for 30 h, 4, 6 and 7 days. Viral DNA evaluation was performed with viable and UV-inactivated virus by q-Real-Time PCR. RNA extracted from latency and reactivation models at 7 days post-infection (p.i.) was subjected to RT-PCR to analyse viral latency and lytic transcripts. To perform viral progeny analysis and titration, the culture medium from infected THP-1 latency and reactivation models (7 days p.i.) was used to infect human fibroblasts; it was also checked for the presence of exosomes.

For viral progeny analysis experiments, the Towne strain was also used.

Results

Our results showed that, while comparable TB40E DNA amounts were present in both latent and reactivation models at 30 h p.i., gradually increased quantities of viral DNA were only evident in the latter model at 4, 6, 7 days p.i.. The completion of the lytic cycle upon reactivation was also proved by the presence of HCMV lytic transcripts and an infectious viral yield at 7 days p.i.

Conclusions

Our data demonstrate the effectiveness of THP-1 cells as a “switch” model for studying the mechanisms that regulate HCMV reactivation from latency. This system is able to provide adequate quantities of cells harbouring latent/reactivated virus, thereby overcoming the intrinsic difficulties connected to the ex vivo system.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-016-0634-z) contains supplementary material, which is available to authorized users.

Cytomegalovirus transmission in pediatric renal transplant recipients during the window period

We report two CMV naïve children who received deceased donor renal transplants from a CMV IgG-negative single donor. CMV IgG in both recipients and the donor were negative immediately prior to transplant. Both recipients had early recurrences of their original disease in their transplants, requiring multiple sessions of plasmapheresis. All blood products used were leukoreduced or CMV seronegative. A few days post-transplant, both recipients developed significant positive CMV viremia. Both required initiation of oral valganciclovir. Case 1 responded to oral valganciclovir only while the case 2 had a delayed response to it and hence required intravenous ganciclovir with good response. When checked retrospectively, CMV IgM in the donor was positive along with positive CMV DNA PCR from the white cells. Here we describe a very unusual scenario of CMV transmission in two pediatric renal transplant recipients from a single donor during the CMV window period.

Systematic Evaluation of Different Nucleic Acid Amplification Assays for Cytomegalovirus Detection: Feasibility of Blood Donor Screening

Acute primary cytomegalovirus (CMV) infections, which commonly occur asymptomatically among blood donors, represent a significant risk for serious morbidity in immunocompromised patients (a major group of transfusion recipients). We implemented a routine CMV pool screening procedure for plasma for the identification of CMV DNA-positive donors, and we evaluated the sensitivities and performance of different CMV DNA amplification systems. Minipools (MPs) of samples from 18,405 individual donors (54,451 donations) were screened for CMV DNA using the RealStar CMV PCR assay (Altona Diagnostic Technologies), with a minimum detection limit of 11.14 IU/ml. DNA was extracted with a high-volume protocol (4.8 ml, Chemagic Viral 5K kit; PerkinElmer) for blood donor pool screening (MP-nucleic acid testing [NAT]) and with the Nuclisens easyMAG system (0.5 ml; bioMérieux) for individual donation (ID)-NAT. In total, six CMV DNA-positive donors (0.03%) were identified by routine CMV screening, with DNA concentrations ranging from 4.35 × 10(2) to 4.30 × 10(3) IU/ml. Five donors already showed seroconversion and detectable IgA, IgM, and/or IgG antibody titers (IgA(+)/IgM(+)/IgG(-) or IgA(+)/IgM(+)/IgG(+)), and one donor showed no CMV-specific antibodies. Comparison of three commercial assays, i.e., the RealStar CMV PCR kit, the Sentosa SA CMV quantitative PCR kit (Vela Diagnostics), and the CMV R-gene PCR kit (bioMérieux), for MP-NAT and ID-NAT showed comparably good analytical sensitivities, ranging from 10.23 to 11.14 IU/ml (MP-NAT) or from 37.66 to 57.94 IU/ml (ID-NAT). The clinical relevance of transfusion-associated CMV infections requires further investigation, and the evaluated methods present powerful basic tools providing sensitive possibilities for viral testing. The application of CMV MP-NAT facilitated the identification of one donor with a window-phase donation during acute primary CMV infection.

Discordant humoral and cellular immune responses to Cytomegalovirus (CMV) in glioblastoma patients whose tumors are positive for CMV

Background. Glioblastoma (GBM) is the most common malignant brain tumor in adults and is nearly always fatal. Emerging evidence suggests that human Cytomegalovirus (HCMV) is present in 90-100% of GBMs and that add-on antiviral treatment for HCMV show promise to improve survival. Methods. In a randomized, placebo-controlled trial of valganciclovir in 42 GBM patients, blood samples were collected for analyses of HCMV DNA, RNA, reactivity against HCMV peptides, IgG, and IgM at baseline and at 3, 12, and 24 weeks of treatment. Results. All 42 tumors were positive for HCMV protein. All patients examined had at least one blood sample positive for HCMV DNA, 63% were HCMV RNA positive, and 21% were IgM positive. However, 29% of GBM patients were IgG negative for HCMV. Five of these samples were positive in an enzyme-linked immunosorbent assay (ELISA) that used antigens derived from a clinical isolate. Blood T cells from 11 of 13 (85%) HCMV IgG-negative GBM patients reacted against HCMV peptides. Valganciclovir did not affect IgG titers, DNA, or RNA levels of the HCMV immediate early (HCMV IE) gene in blood. Conclusion. In GBM patients, HCMV activity is higher than in healthy controls and serology is a poor test to define previous or active HCMV infection in these patients.

Male infertility: a public health issue caused by sexually transmitted pathogens

Sexually transmitted diseases (STDs) are caused by several pathogens, including bacteria, viruses and protozoa, and can induce male infertility through multiple pathophysiological mechanisms. Additionally, horizontal transmission of STD pathogens to sexual partners or vertical transmission to fetuses and neonates is possible. Chlamydia trachomatis, Ureaplasma spp., human papillomavirus, hepatitis B and hepatitis C viruses, HIV-1 and human cytomegalovirus have all been detected in semen from symptomatic and asymptomatic men with testicular, accessory gland and urethral infections. These pathogens are associated with poor sperm quality and decreased sperm concentration and motility. However, the effects of these STD agents on semen quality are unclear, as are the effects of herpes simplex virus type 1 and type 2, Neisseria gonorrhoeae, Mycoplasma spp., Treponema pallidum and Trichomonas vaginalis, because few studies have evaluated the influence of these pathogens on male infertility. Chronic or inadequately treated infections seem to be more relevant to infertility than acute infections are, although in many cases the exact aetiological agents remain unknown.

The use of primary human cells (fibroblasts, monocytes, and others) to assess human cytomegalovirus function

The extensive tropism of human cytomegalovirus (HCMV) results in the productive infection of multiple cell types within the human host. However, infection of other cell types, such as undifferentiated cells of the myeloid lineage, gives rise to nonpermissive infections. This has been used experimentally to model latent infection which is known to be established in the pluripotent CD34+ hematopoietic progenitor cell population resident in the bone marrow in vivo. The absence of a tractable animal model for studies of HCMV has resulted in a number of laboratories employing experimental infection of cells in vitro to simulate both HCMV lytic and latent infection. Herein, we will focus on the techniques used in our laboratory for the isolation and use of primary cells to study aspects of HCMV latency, reactivation, and lytic infection.

The prevalence and risk factors of cytomegalovirus infection in inflammatory bowel disease in Wuhan, Central China

BACKGROUND

The etiology of inflammatory bowel disease (IBD) is not clear and cytomegalovirus (CMV) infection is often associated with IBD patients. The etiologic link between IBD and CMV infection needs to be studied. The objective of the present study is to investigate the prevalence and risk factors of CMV in a cohort of IBD patients from Central China.

METHODS

Two hundred and twenty six IBD patients (189 ulcerative colitis (UC) and 37 patients with Crohn's disease (CD)), and 290 age and sex matched healthy controls were recruited. CMV DNA was detected by nested PCR, while serum anti-CMV IgG and anti-CMV IgM was determined by ELISAs. Colonoscopy/enteroscopy with biopsy of diseased tissues and subsequent H&E stain were then conducted in IBD patients with positive anti-CMV IgM. Finally, we analyzed the prevalence and clinical risk factors of CMV infection in IBD patients.

RESULTS

The prevalence of CMV DNA and anti-CMV IgG positive rate in IBD patients were 84.07% and 76.11%, respectively, higher than those in healthy controls (59.66% and 50.69%, respectively, P < 0.05), However, anti-CMV IgM positive rate was no different with healthy controls (1.77% vs 0.34%, P = 0.235). In univariate analysis of risk factors, the recent use of corticosteroid was associated with increase of CMV DNA and IgM positive rate in UC (P = 0.035 and P = 0.015, respectively), aminosalicylic acid drug therapy was correlated with positivity of CMV DNA and IgG in UC and CMV DNA in CD (P = 0.041, P < 0.001 and P = 0.014, respectively), the treatment of immunosuppresent was correlated with CMV IgM (P < 0.001). Furthermore, patients with severe UC were significantly associated with CMV DNA and IgM (P = 0.048 and P = 0.031, respectively). Malnutrition (albumin < 35 G/L) was also found to be related with CMV recent infection (P = 0.031). In multivariate analysis of risk factors in UC, pancolitis was significantly associated with CMV DNA positivity (P = 0.001). Severe UC and pancolitis seemed to be related with IgG positivity. For CD, there was just single factor associated with CMV positive in each group, multivariate analysis was unnecessary.

CONCLUSIONS

CMV positive rate in IBD patients was significantly higher, than in healthy controls. The use of aminosalicylic acid, corticosteroid, immunosuppressants, pancolitis and severe IBD patients seemed to be more susceptible to CMV infection in univariate analysis of risk factors. However, no risk factor was found to be significantly correlated with CMV infection in multivariate analysis of risk factors.

The National Heart, Lung, and Blood Institute retrovirus epidemiology donor studies (Retrovirus Epidemiology Donor Study and Retrovirus Epidemiology Donor Study-II): twenty years of research to advance blood product safety and availability

The Retrovirus Epidemiology Donor Study (REDS), conducted from 1989 to 2001, and the REDS-II, conducted from 2004 to 2012, were National Heart, Lung, and Blood Institute-funded, multicenter programs focused on improving blood safety and availability in the United States. The REDS-II also included international study sites in Brazil and China. The 3 major research domains of REDS/REDS-II have been infectious disease risk evaluation, blood donation availability, and blood donor characterization. Both programs have made significant contributions to transfusion medicine research methodology by the use of mathematical modeling, large-scale donor surveys, innovative methods of repository sample storage, and establishing an infrastructure that responded to potential emerging blood safety threats such as xenotropic murine leukemia virus-related virus. Blood safety studies have included protocols evaluating epidemiologic and/or laboratory aspects of human immunodeficiency virus, human T-lymphotropic virus 1/2, hepatitis C virus, hepatitis B virus, West Nile virus, cytomegalovirus, human herpesvirus 8, parvovirus B19, malaria, Creutzfeldt-Jakob disease, influenza, and Trypanosoma cruzi infections. Other analyses have characterized blood donor demographics, motivations to donate, factors influencing donor return, behavioral risk factors, donors' perception of the blood donation screening process, and aspects of donor deferral. In REDS-II, 2 large-scale blood donor protocols examined iron deficiency in donors and the prevalence of leukocyte antibodies. This review describes the major study results from over 150 peer-reviewed articles published by these 2 REDS programs. In 2011, a new 7-year program, the Recipient Epidemiology and Donor Evaluation Study-III, was launched. The Recipient Epidemiology and Donor Evaluation Study-III expands beyond donor-based research to include studies of blood transfusion recipients in the hospital setting and adds a third country, South Africa, to the international program.

Recombinant antibodies encoded by IGHV1-69 react with pUL32, a phosphoprotein of cytomegalovirus and B-cell superantigen

Leukemia cells from patients with chronic lymphocytic leukemia (CLL) express a highly restricted immunoglobulin heavy variable chain (IGHV) repertoire, suggesting that a limited set of antigens reacts with leukemic cells. Here, we evaluated the reactivity of a panel of different CLL recombinant antibodies (rAbs) encoded by the most commonly expressed IGHV genes with a panel of selected viral and bacterial pathogens. Six different CLL rAbs encoded by IGHV1-69 or IGHV3-21, but not a CLL rAb encoded by IGHV4-39 genes, reacted with a single protein of human cytomegalovirus (CMV). The CMV protein was identified as the large structural phosphoprotein pUL32. In contrast, none of the CLL rAbs bound to any other structure of CMV, adenovirus serotype 2, Salmonella enterica serovar Typhimurium, or of cells used for propagation of these microorganisms. Monoclonal antibodies or humanized rAbs of irrelevant specificity to pUL32 did not react with any of the proteins present in the different lysates. Still, rAbs encoded by a germ line IGHV1-69 51p1 allele from CMV-seropositive and -negative adults also reacted with pUL32. The observed reactivity of multiple different CLL rAbs and natural antibodies from CMV-seronegative adults with pUL32 is consistent with the properties of a superantigen.

Relationship between cytomegalovirus (CMV) IgG serology, detectable CMV DNA in peripheral monocytes, and CMV pp65(495-503)-specific CD8+ T cells in older adults

In immunocompetent individuals, cytomegalovirus (CMV) is thought to persist in a latent state in monocytes and myeloid progenitor cells, establishing a lifelong infection. In CMV-seropositive older adults, aging has been associated with both expansion of CMV pp65(495-503)-specific CD8(+) T cell clones and shrinkage of the T cell repertoire that characterize T cell immunosenescence. In fact it has been suggested that chronic CMV infection is a driving force in age-related T cell immunosenescence. In older adults, chronic CMV infection is conventionally diagnosed by positive IgG serology which does not distinguish between past and persistent infections. To better define the relationship between chronic CMV infection and expansion of CMV pp65(495-503)-specific CD8(+) T cells, we directly assessed CMV viral DNA in monocyte-enriched peripheral blood mononuclear cells in 16 HLA-A2-positive elderly volunteers (mean age = 83 years). While all participants had positive CMV IgG serology by enzyme-linked immunosorbent assays, only nine (56%) had detectable CMV DNA by nested polymerase chain reaction. These nine individuals had significantly higher percentages of CMV pp65(495-503) tetramer-positive CD8(+) T cells (median = 1.3%) than those without detectable CMV DNA (median = 0.1%; p < 0.001). Absolute CMV IgG antibody titers did not differ between these two groups (median = 54.6 vs 44.2 EU/ml, respectively, p = 0.4). CMV IgM titers were negative for all 16 participants, suggesting that recent primary CMV infection was unlikely. These results demonstrate a strong association between the presence of CMV DNA in peripheral monocytes and the expansion of CD8(+) T cells specific for the CMV immunodominant epitope pp65(495-503). Although the sample size in this study is relatively small, these findings provide initial evidence suggesting the heterogeneity of CMV IgG-seropositive older adult population and CMV viral DNA detection in peripheral monocytes as an informative tool to better understand the relationship between chronic CMV infection and T cell immunosenescence.

Association of detectable cytomegalovirus (CMV) DNA in monocytes rather than positive CMV IgG serology with elevated neopterin levels in community-dwelling older adults

In immunocompetent persons, cytomegalovirus (CMV) is thought to persist primarily in monocytes and myeloid progenitor cells, establishing a chronic infection. In older adults, chronic CMV infection is typically diagnosed by a positive IgG serology. While many studies have shown CMV-specific T-cell expansion in CMV seropositive older individuals, significant heterogeneity has also been observed in this elderly population. In a study of 71 community-dwelling older adults, we assessed CMV viral DNA in peripheral monocytes by nested PCR and compared the relationships of detectable CMV DNA and IgG serology with serum levels of neopterin, a marker for monocyte/macrophage-mediated immune activation. The results showed that 52 (73.2%) participants were CMV seropositive, of whom 30 (57.5%) had detectable CMV DNA. CMV seropositive and seronegative participants did not differ in their neopterin levels, but individuals with detectable CMV DNA had higher neopterin than those without (10.6 ± 4.4 vs 8.0 ± 1.9 nM, respectively, p<.0001) adjusting for demographic and clinical covariates and interferon (IFN)-γ levels. In addition, there was no association between IgG titers and neopterin. These findings suggest that detection of CMV viral DNA in monocytes may be an informative tool to evaluate chronic CMV infection and its potential role in monocyte/macrophage-mediated immune activation in the elderly.

Virally induced changes in cellular microRNAs maintain latency of human cytomegalovirus in CD34⁺ progenitors

One site of latency of human cytomegalovirus (HCMV; human herpesvirus 5) is known to be CD34(+) haematopoietic progenitor cells, and it is likely that carriage of latent virus has profound effects on cellular gene expression in order to optimize latency and reactivation. As microRNAs (miRNAs) play important roles in regulating stem-cell gene expression, this study asked whether latent carriage of HCMV led to changes in cellular miRNA expression. A comprehensive miRNA screen showed the differential regulation of a number of cellular miRNAs during HCMV latency in CD34(+) progenitor cells. One of these, hsa-miR-92a, was robustly decreased in three independent miRNA screens. Latency-induced change in hsa-miR-92a results in an increase in expression of GATA-2 and subsequent increased expression of cellular IL-10, which aids the maintenance of latent viral genomes in CD34(+) cells, probably resulting from their increased survival.

Prevention of transfusion-transmitted cytomegalovirus in low-birth weight infants (≤1500 g) using cytomegalovirus-seronegative and leukoreduced transfusions

The transfusion-transmitted cytomegalovirus (TT-CMV) can cause serious morbidity and mortality in low-birth weight infants (LBWIs). Transfusion-transmitted cytomegalovirus can be minimized in LBWIs born to cytomegalovirus (CMV)-seronegative mothers with the use of CMV-seronegative blood components. Despite evidence that has independently shown that either leukoreduction or the use of CMV-seronegative components mitigates TT-CMV, the potential efficacy of combining these 2 strategies has not been substantiated in very LBWIs (<1500 g) born to either CMV-seronegative or CMV-seropositive mothers. Nonetheless, the serious risks of CMV infection posed by allogeneic transfusions and the broad implementation of universal leukoreduction have made this combination strategy the de facto clinical standard for transfusion of LBWIs. Although preferred, this combined approach has not been validated in clinical trials and, thus, warrants a large prospective study to determine whether this is the optimal transfusion tactic or if additional safety measures are necessary to prevent TT-CMV in LBWIs born to both CMV- seronegative and CMV-seropositive mothers. The aim of this prospective birth cohort study, therefore, is to estimate the incidence of TT-CMV in 1300 LBWIs (≤1500 g) who receive CMV-seronegative plus leuko-reduced blood products to evaluate the effectiveness of this coupled strategy. Conducted in Atlanta, GA, this study has been registered at the US National Institutes of Health (ClinicalTrials.gov no. NCT00907686).

Latent cytomegalovirus infection exacerbates experimental colitis

Inflammatory bowel disease (IBD) severity is positively correlated with cytomegalovirus (CMV) infection. This may reflect CMV triggering and/or exacerbating flares of IBD and/or IBD or immunosuppressive drugs administered to patients with IBD increasing susceptibility to CMV infection. Herein, we performed studies in mice to investigate these possibilities. Mice administered murine CMV (MCMV) developed signs of acute viral infection (malaise and weight loss) and had MCMV loads that were readily detected in numerous organs including the intestine. By 4 weeks, these mice manifested a "latent" infection in which MCMV levels were low but detectable by PCR. Such MCMV infection did not induce acute colitis in either wild-type mice or IL-10(-/-) mice, which are highly prone to developing colitis. However, underlying MCMV infection in an acute or latent state exacerbated the severity of colitis induced by dextran sodium sulfate (DSS). Such potentiation of DSS colitis by latent MCMV infection seemed to occur without viral reactivation. Whereas initial MCMV infection induced acute alterations in serum and intestinal cytokines, such cytokine levels returned to baseline before administration of DSS. However, the initial infection resulted in lasting elevation of antibodies to commensal bacterial antigens, suggesting that MCMV infection may have potentiated colitis via priming of the intestinal immune response to gut microbiota. Thus, underlying CMV infection can alter mucosal immunity, potentially increasing the tendency of CMV-infected hosts to develop colitis.

Relationship of cytomegalovirus load assessed by real-time PCR to pp65 antigenemia in organ transplant recipients

BACKGROUND

Cytomegalovirus (CMV) infection in immunocompromised patients can lead to viremia associated with morbidity and mortality. Monitoring of viral loads in blood is critical for initiating and monitoring antiviral treatment.

OBJECTIVES

Validate quantitative real-time PCR assay targeting the US17 and UL54 regions of the CMV genome for automated DNA and extraction and amplification.

STUDY DESIGN

3422 blood specimens from organ transplant recipients, including longitudinal specimens from 12 organ transplant recipients, were tested by CMV PCR and pp65 antigenemia.

RESULTS

CMV PCR for both US17 and UL54, was more sensitive and detected CMV DNA earlier and for longer than the CMV pp65 antigenemia test. Using antigenemia results as a reference standard, an optimal cutoff of 500 normalized copies was calculated for both US17 and UL54 PCR targets based on high sensitivity, specificity, and positive and negative predictive values. CMV DNA levels tracked well with clinical symptoms, response to treatment, and antigenemia.

CONCLUSIONS

Detection of persistent increases in CMV DNA levels above 500 normalized copies by this real-time PCR assay is indicative of symptomatic CMV disease in organ transplant recipients. Quantitative real-time PCR for CMV DNA can be used in lieu of antigenemia for monitoring CMV infection and determining when to initiate preemptive treatment.

Human cytomegalovirus: Latency and reactivation in the myeloid lineage

Human cytomegalovirus (HCMV) persists as a sub-clinical, lifelong infection in the human host which is maintained at least in part by its carriage in the absence of detectable infectious virus: a hallmark of latent infection. In contrast, reactivation from latency in immuno-compromised individuals can result in serious disease. Understanding virus latency and reactivation, therefore, is essential for a full understanding of the biology and pathogenesis of this persistent human herpesvirus. However, the precise cellular sites in which HCMV is carried and the mechanisms regulating its latency and reactivation, during natural infection, remain poorly understood. Recent work, however, has led to a consensus opinion that cells of the myeloid lineage are one site of carriage of HCMV in vivo and that in myeloid dendritic cell (DC) progenitors the viral genome is carried latently in the absence of virus lytic gene expression. In contrast, differentiation of these cells to a mature DC phenotype is linked with reactivation of infectious virus resulting from differentiation-dependent chromatin remodelling of the viral major immediate-early promoter. Thus there is a crucial link between the differentiation of myeloid cells and transcriptional reactivation of latent virus which is likely to play a key role in viral pathogenesis.

Herpesvirus prevalence and viral load in healthy blood donors by quantitative real-time polymerase chain reaction

BACKGROUND

After primary infection, human herpesviruses (HHVs) maintain long-term latent persistence, often punctuated years later by sporadic episodes of symptomatic lytic activation. Also, blood-borne herpesvirus from healthy persistently infected blood donors can lead to active primary infection of immunocompromised transfusion recipients.

STUDY DESIGN AND METHODS

Utilizing a set of newly developed real-time polymerase chain reaction assays for detection and quantification of all eight human herpesviruses, the prevalence and viral DNA load of white cell-enriched blood from 100 randomly selected blood donors from the southeast Texas region are reported.

RESULTS

Herpes simplex viruses 1 and 2 (HSV-1 and HSV-2), varicella-zoster virus (VZV), and HHV-8 DNA were not detected in any donor sample. In contrast, Epstein-Barr virus (EBV) (72%) and HHV-7 (65%) were commonly detected, HHV-6 (30%) was often detected (Type B only), and cytomegalovirus (CMV; 1%) was rarely detected. Median viral loads of positive samples (per milliliter of blood) ranged from 4278 for HHV-6 to less than 46 for EBV.

CONCLUSIONS

These results suggest that the potential for transfusion-mediated transmission of herpesviruses from healthy adult blood donors is high for EBV and HHV-7; moderately high for HHV-6; uncommon for CMV; and rare for HSV-1, HSV-2, VZV, and HHV-8. Perhaps the most remarkable finding in this study was the detection of a single donor sample with greater than 6.1 x 10(7) HHV-6 Type B genome equivalents per mL blood. Given that this extraordinarily high level of HHV-6 DNA was obtained from a healthy adult blood donor, this phenomenon is likely unrelated to active infection or immunodeficiency.

Determination of suitable housekeeping genes for normalisation of quantitative real time PCR analysis of cells infected with human immunodeficiency virus and herpes viruses

The choice of an appropriate housekeeping gene for normalisation purposes has now become an essential requirement when designing QPCR experiments. This is of particular importance when using QPCR to measure viral and cellular gene transcription levels in the context of viral infections as viruses can significantly interfere with host cell pathways, the components of which traditional housekeeping genes often encode. In this study we have determined the reliability of 10 housekeeping genes in context of four heavily studied viral infections; human immunodeficiency virus type 1, herpes simplex virus type 1, cytomegalovirus and varicella zoster virus infections using a variety of cell types and virus strains. This provides researchers of these viruses with a shortlist of potential housekeeping genes to use as normalisers for QPCR experiments.

Transfusion-Transmitted Cytomegalovirus: Lessons From a Murine Model

Transfusion-transmitted cytomegalovirus (CMV) infection (TT-CMV) continues to complicate blood transfusion therapy, which can lead to severe morbidity or mortality in immunocompromised or immuno-immature recipients. The biological mechanisms that underlie TT-CMV (eg, viral latency in donor monocytes or stimulatory signals in the transfusion recipient leading to cytomegalovirus reactivation) are difficult to study in humans, but can be addressed in animal models. In this review, we discuss a mouse blood transfusion model, which can be used to investigate these issues as well as to validate methods to prevent TT-CMV in at-risk patients.

Latency-associated human cytomegalovirus glycoprotein N genotypes in monocytes from healthy blood donors

BACKGROUND

The beta-herpesvirus human cytomegalovirus (HCMV) infects a variety of cell types and maintains a lifelong relationship with its host by way of a latent infection in circulating monocytes, myeloid precursor cells, and the hematopoietic progenitor population. Viral strain heterogeneity, shown by gene polymorphisms, has been implicated in the majority of HCMV biologic behaviors. HCMV UL73 encodes the polymorphic envelope glycoprotein N (gN), which shows seven genotypes (gN-1, gN-2, gN-3a, gN-3b, gN-4a, gN-4b, and gN-4c).

STUDY DESIGN AND METHODS

Monocyte subfractions from 64 HCMV-seropositive healthy blood donors were collected to analyze gN genotypes distribution in the few cells harboring the latent viral genome. Different experimental approaches to extract viral genomes from the monocyte population and amplify UL73 (polymerase chain reaction touchdown and nested) for subsequent genotyping were tested and compared with diagnostic gold standard. gN genotype distribution in monocytes from immunocompetent healthy carriers was compared with previously reported data obtained from patient populations with acute HCMV infections.

RESULTS

The efficiency of UL73 amplification from monocytes of healthy seropositive blood donors was approximately 39 percent, one of the highest reported to date. The leading gN genotype was gN-1 (87%), whereas the gN-4 variant was poorly represented (13%). The comparison of gN genotypic frequencies in the immunocompetent healthy population with immunocompromised patients is discussed.

CONCLUSIONS

This work further supports the idea that strain-specific features could determine the cell tropism and influence the onset of latency.

The Role of Photochemical Treatment With Amotosalen and UV-A Light in the Prevention of Transfusion-Transmitted Cytomegalovirus Infections

Primary cytomegalovirus (CMV) infection is usually asymptomatic in immunocompetent patients but can cause serious life-threatening complications in immunocompromised CMV-seronegative patients, including patients receiving a bone marrow or peripheral blood stem cell transplant, recipients of some solid-organ transplants, and low-birth-weight neonates. Current recommendations for preventing transfusion-transmitted CMV (TT-CMV) infection in these patients include exclusive use of CMV-seronegative and/or leukoreduced cellular blood components (red blood cells and platelets) for transfusion. However, breakthrough cases of TT-CMV still occur. Despite improving the safety of blood components, testing remains a reactive approach to blood safety. In contrast, pathogen inactivation technologies offer a proactive approach with the potential to further improve blood safety. To reduce the risks associated with platelet transfusions, a photochemical treatment (PCT) process using a combination of the psoralen amotosalen HCl and long-wavelength UV light has been developed and introduced into clinical practice in Europe. PCT has been shown to result in greater than 5.9-log reductions in infectivity of human CMV in platelet concentrates and to prevent the transfusion transmission of murine CMV in a mouse transfusion model. Thus, PCT pathogen inactivation may play a role in further reducing the incidence of TT-CMV infection in patients who are at risk for serious CMV disease. Because PCT is a technology that targets nucleic acids, it also offers a proactive process for the inactivation of a broad range of viral, bacterial, and protozoan pathogens in addition to CMV.

Comparison of cytomegalovirus polymerase chain reaction and serology for screening umbilical cord blood components

BACKGROUND

Recipients of umbilical cord blood (UCB) transplants are susceptible to opportunistic infections, including cytomegalovirus (CMV). To prevent CMV transmission from UCB donors, most laboratories perform serology on corresponding maternal samples and quarantine units when the mother has immunoglobulin M (IgM) anti-CMV.

STUDY DESIGN AND METHODS

UCB units and associated samples (UCB plasma and red cell pellet; maternal whole blood and serum) from two cord blood banks were tested with two validated CMV polymerase chain reaction assays (UL54 and UL93 targets). Results were compared with maternal CMV serology (IgG and IgM).

RESULTS

Only 4 of 48 (8.3%) quarantined CMV IgM-positive units were also CMV nucleic acid testing (NAT)-positive (651-68,600 copies/mL). In contrast, 1 of 200 "CMV-safe" UCB units (CMV IgM-equivocal or -negative) had CMV DNA (0.5%). The corresponding maternal samples were CMV NAT-negative. Positive maternal IgM serology demonstrates only modest sensitivity (80%) and specificity (82%) and poor positive predictive value (8%), when correlated with the presence of CMV DNA in UCB units.

CONCLUSION

CMV NAT may be a useful adjunct to serologic screening, potentially reducing wastage of IgM-positive and NAT-negative units while also detecting potentially infectious units that would pass serologic screening. A prospective clinical trial to further evaluate the role of CMV NAT in UCB transplantation appears warranted.

Towards the prevention of transfusion-transmitted infectious diseases

Transfusion-transmission of viral infections, such as HIV and hepatitis C virus, were once the scourge of blood transfusion. However, due to remarkable progress over the last 30 years, tests for viral proteins, antibody responses and more recently, viral nucleic acids, have virtually eliminated these risks. This review summarizes these advances in an historical context, describes new methodologies on the horizon, and discusses residual infectious risks associated with blood transfusion.

Induction of latent human cytomegalovirus by conventional gamma irradiation and prevention by treatment with INACTINE PEN110

BACKGROUND AND OBJECTIVES

Two different leucocyte-inactivation technologies--gamma irradiation and INACTINE PEN110--were evaluated for their effects on cell-associated human cytomegalovirus (CMV).

MATERIALS AND METHODS

In vitro CMV-infected cells were spiked into leucoreduced red blood cell concentrates (RCC) or medium at a final concentration of 0.5 - 1 x 10(7) cells/ml to mimic non-leucoreduced levels of leucocytes. The spiked RCC/medium was divided into three equal units and treated with gamma irradiation at the US Food and Drug Administration (FDA)-approved dose of 25 Gy, with 0.1% v/v PEN110 at 22 degrees C for 24 h, or stored at 4 degrees C as a control. The treated and control cells were recovered and tested using infectivity, viability and polymerase chain reaction (PCR) assays.

RESULTS

Gamma-irradiated CMV-infected cells produced active virus, as shown by both infectivity assays and PCR quantification of viral DNA. PCR analysis demonstrated higher CMV DNA levels in gamma-irradiated, latently infected monocytic THP-1 cells than untreated control cells. The increased virus production in gamma-irradiated cells was paralleled by an increased metabolic rate and the development of enlarged multinuclear cells. In contrast, PEN110 treatment terminated virus replication and completely inactivated the infected cell.

CONCLUSIONS

These results demonstrate that gamma irradiation, at levels currently used to treat RCC, has the capacity to induce expression of CMV, whereas PEN110 inhibits CMV replication and efficiently inactivates the infected cells.

Photochemical treatment of platelet concentrates with amotosalen hydrochloride and ultraviolet A light inactivates free and latent cytomegalovirus in a murine transfusion model

BACKGROUND

A photochemical treatment (PCT) process utilizing amotosalen hydrochloride and long wavelength UVA light has been developed to inactivate pathogens in PLTs. This study investigated the effects of amotosalen/UVA treatment on free and latent murine CMV (MCMV) in PLT preparations using a murine model of transfusion-transmitted CMV (TT-CMV).

STUDY DESIGN AND METHODS

In a model of latent MCMV infection, "donor" mice received 1 x 10(6) plaque-forming units (PFUs) MCMV and were rested 14 days. Subsequently harvested, pooled, and washed WBCs were PCR positive for MCMV. Murine WBC doses of 1 x 10(4), 1 x 10(5), and 1 x 10(6) were added to human apheresis PLTs in 35 percent autologous plasma and 65 percent PLT AS (PAS). The WBC-PLT products were treated with 150 micro mol/L amotosalen and 0.6 J per cm2 UVA and transfused via tail vein injection into recipient mice. Recipients were killed on Day 14. Blood and spleens were collected and assayed for MCMV by PCR. In a parallel model of active infection with free virus, human PLT in 35 percent autologous plasma and 65 percent PAS were dosed with 1 x 10(5) and 1 x 10(6) PFUs of MCMV. All other procedures were as described above.

RESULTS

In the absence of amotosalen/UVA-pretreatment, transfusion of PLT latently or actively infected with MCMV produced TT-CMV in a dose-dependent fashion. In contrast, all transfusion recipients of identical PLT preparations pretreated with amotosalen/UVA were uniformly PCR negative for MCMV (abrogation of TT-CMV; p < 0.05).

CONCLUSIONS

PCT of PLT preparations with the specified doses of amotosalen hydrochloride and UVA light prevents transfusion transmission of free and latent MCMV in a murine model. These results suggest that PCT of human PLTs with amotosalen/UVA should also effectively abrogate TT-CMV in the clinical setting.

Recognition of cytomegalovirus clinical isolate antigens by sera from cytomegalovirus-negative blood donors

BACKGROUND

The most common way to prevent transmission of CMV by blood transfusion is to use blood products from seronegative donors. Screening of blood donors for CMV infection is usually based on detection of antigens obtained from the CMV laboratory strain AD 169. Recent evidence suggests that approximately up to 20 percent of CMV-negative blood donors may in fact be CMV-DNA positive by PCR analyses.

STUDY DESIGN AND METHODS

In this study, sera from CMV-seronegative, CMV-seropositive, and CMV-DNA-positive/seronegative individuals, and from patients with acute and convalescent CMV infection for detection of CMV antibodies were analyzed. CMV antigens prepared from cells infected with CMV clinical isolates or the CMV laboratory strain AD 169 in ELISA and Western blot assays were used.

RESULTS

All CMV-positive sera from blood donors were seropositive for the CMV antigens prepared from AD 169 (A2) or from a CMV clinical isolate (C6). Interestingly, whereas all CMV-negative blood donors were negative in tests for the CMV antigen A2, 36 percent were CMV seropositive using the CMV antigen C6 in ELISA.

CONCLUSION

The data suggest that a substantial number of CMV-seronegative/CMV-DNA-positive serum samples contain antibodies that recognize CMV clinical isolate antigens.

Assessment of removal of human cytomegalovirus from blood components by leukocyte depletion filters using real-time quantitative PCR

To assess removal of cytomegalovirus (CMV) by leukocyte depletion (LD) filters, we developed a spiking model of latent virus using peripheral blood mononuclear cells (PBMCs) infected by coculture with CMV-infected human fibroblasts. Infected PBMCs were purified by dual magnetic column selection and then spiked into whole blood units or buffy coat pools prior to LD by filtration. CMV load and fibroblast contamination were assessed using quantitative CMV DNA real-time PCR and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) of mRNA encoding the fibroblast-specific splice variant of prolyl-4-hydroxylase, respectively. After correcting for fibroblast-associated CMV, the mean CMV load was reduced in whole blood by LD from 7.42 x 10(2) to 1.13 copies per microliter (2.81(10)log reduction) and from 3.8 x 10(2) to 4.77 copies per microliter (1.9(10)log reduction) in platelets. These results suggest that LD by filtration reduces viral burden but does not completely remove CMV from blood components.

CMV DNA is rarely detected in healthy blood donors using validated PCR assays

BACKGROUND

Although serologic screening or WBC reduction of blood components can reduce the incidence of transfusion-transmitted CMV (TT-CMV) infection, 'breakthrough' cases of TT-CMV still occur and may produce serious sequelae. NAT of blood components for CMV DNA has been proposed to further reduce the risks of TT-CMV. However, large-scale studies to determine the utility of validated CMV NAT assays for donor screening have not been reported.

STUDY DESIGN AND METHODS

Coded whole-blood samples (n=1000) were tested for the presence of CMV DNA using two CMV PCR assays previously validated in a multicenter trial (a nested PCR assay directed at the CMV UL93 open-reading frame and the Roche Monitor assay). Corresponding plasma samples were tested in parallel for the presence of anti-CMV using other assays (Abbott CMV EIA and Fujirebio/Olympus CMV particle agglutination assays).

RESULTS

In total 416 and 514 of the samples tested as CMV-seropositive and -seronegative, respectively, by both antibody assays. The remaining 70 samples had discrepant serology results. Only 2 of the 1000 samples (both seropositive) had reproducibly detectable CMV DNA (positive in at least three of four replicates). CMV DNA was not reproducibly detected in seronegative samples or in samples with discrepant serology results.

CONCLUSIONS

Although previous investigations showed frequent detection of CMV DNA in healthy CMV-seropositive (and some seronegative) blood donors, these studies were relatively small and the performance characteristics of their assays were difficult to evaluate. In contrast, the present large cross-sectional study of US donors utilized two previously validated PCR assays and demonstrated that CMV DNA is only rarely detectable in seropositive donors. Thus, the use of CMV PCR assays with optimal performance characteristics did not increase the detection of potentially infectious blood components beyond that provided by current serologic screening assays.

Frequency and duration of plasma CMV viremia in seroconverting blood donors and recipients

BACKGROUND

Both CMV-seronegative blood and unscreened, filtered blood carry a low but definite risk of transmitting CMV infection. To explain this residual risk, evidence of cell-free viremia was sought in seroconverting and seroprevalent blood donors and seroconverting transfusion recipients by means of a plasma-based assay for CMV DNA.

STUDY DESIGN AND METHODS

A CMV DNA PCR assay (COBAS Amplicor CMV Monitor, Roche) was used to detect CMV DNA in 384 paired plasma samples from 192 donors who seroconverted to anti-CMV, 488 anti-CMV EIA-positive samples from 60 seroprevalent donors, and 113 serial samples from 11 seroconverting recipients with posttransfusion CMV hepatitis.

RESULTS

Three of 384 samples from 192 seroconverting donors had low levels of plasma CMV DNA (400-1600 copies/mL); one donor was positive before seroconversion, and the other two, after seroconversion. None of the 488 serial samples from 60 anti-CMV- positive donors contained CMV DNA in plasma. Three of 11 recipients demonstrated transient plasma viremia that temporally coincided with seroconversion.

CONCLUSIONS

Plasma CMV DNA was detected in a small percentage of seroconverting blood donors and a larger percentage of recipients but was undetectable in seroprevalent donors. Plasma viremia in seroconverting donors may partially explain the low residual risk of CMV transmission by both CMV-seronegative and WBC-reduced seropositive blood.

Broad-spectrum virus reduction in red cell concentrates using INACTINE PEN110 chemistry

BACKGROUND AND OBJECTIVES

The risk of transmission of blood-borne pathogens by transfusion is a persistent problem in medicine. To address this safety issue, INACTINE PEN110 chemistry is being utilized to develop a process for preparing pathogen-reduced red blood cell concentrates (RBCC). The purpose of this study was to characterize the virucidal effectiveness of the INACTINE PEN110 chemistry in full units of RBCC by using a panel of viruses with diverse properties in composition, size and shape.

MATERIALS AND METHODS

The panel included four enveloped (bovine viral diarrhoea virus, pseudorabies virus, vesicular stomatitis Indiana virus and sindbis virus), six non-enveloped (porcine parvovirus, human adenovirus 2, reovirus 3, vesicular exanthema of swine virus, bluetongue virus, and foot and mouth disease virus) and cell-associated (human immunodeficiency) viruses. All viruses were individually spiked into CPD/AS-1, CP2D/AS-3 and CPD/AS-5 RBCC units and treated with 0.1% PEN110 (vol/vol) at 22 +/- 2 degrees C for up to 22 +/- 2 h. The PEN110 treatment reaction was stopped by chemical quenching, and residual virus was assayed. The cytotoxicity effect of PEN110-treated RBCC on indicator cells and the potential interference with the ability of the virus to infect indicator cells was determined and taken into consideration for calculating the virus-reduction factors, to avoid underestimation or overestimation of the virus reduction.

RESULTS

The kinetics of inactivation for viruses spiked into CPD/AS-1, CP2D/AS-3 and CPD/AS-5 RBCC were equivalent. All viruses analysed in this study were reduced to the limit of detection of the assay. The reduction factors for the virus panel ranged from 4.2 to 7.5 log10/ml.

CONCLUSIONS

The results from the study demonstrate for the first time that a pathogen-reduction technology for RBCC can achieve a broad-spectrum virucidal effect against both enveloped and non-enveloped viruses. The broad spectrum of virucidal activity of INACTINE PEN110, and equivalent kinetics of virus inactivation in RBCC prepared using different commercially available RBC storage solutions, demonstrate the robustness of this pathogen-reduction process.

CMV and blood transfusions

Among the human herpesviruses, cytomegalovirus (CMV) is the only one that has assumed significant importance in blood transfusion. Transfusion transmission of CMV (TT-CMV) to seronegative immunocompromised patients can lead to lethal CMV disease. Studies over the past 30 years have demonstrated that monocytes latently infected with CMV represent the primary vector for TT-CMV, and that TT-CMV can be largely abrogated by transfusing at-risk patients with either seronegative units or blood filtered to remove white blood cells. However, the small number of cases of breakthrough TT-CMV that follow transfusion of either seronegative or filtered blood still produce morbidity and mortality. These circumstances have motivated ongoing efforts to provide improved protection from TT-CMV, including the use of CMV DNA amplification for blood screening, and pathogen inactivation to sterilise all blood components prior to transfusion.