Rapid quantitative PCR assays for the simultaneous detection of herpes simplex virus, varicella zoster virus, cytomegalovirus, Epstein-Barr virus, and human herpesvirus 6 DNA in blood and other clinical specimens

Quantification of low-level human cytomegalovirus and Epstein-Barr virus DNAemia by digital PCR

BACKGROUND

Digital PCR (dPCR) can quantify cell-free viral DNA (DNAemia), a biomarker of active viral infection. To accelerate epidemiologic investigation into low-level viral reactivation in chronic disease, we have evaluated the performance of dPCR to detect cytomegalovirus (CMV) and Epstein-Barr virus (EBV) DNAemia across platforms and blood matrices.

METHODS

The droplet-based (BioRad) dPCR platform performance was compared to chip-based (BioMark), and assay validation followed dMIQE guidelines. CMV and EBV DNA reference materials were spiked into known negative plasma and serum samples. In addition, two independent cohorts of ovarian cancer patients were evaluated for viral DNAemia (n = 65 serum and 79 plasma samples).

RESULTS

The limit of quantification (LOQ) was at or slightly above 100 copies/mL for both instruments: 105-135 copies/mL for droplet-based detection and 100 copies/mL for chip-based detection. DNAemia in serum had a slightly lower LOQ (105-110 copies/mL) compared to plasma (LOQ; 115-135 copies/mL). The variation (CV) coefficients for each assay and machine were less than 5 %. In patient samples, CVs ranged from 4.5 - 7.4 % and were similar for cell-free DNA derived from serum or plasma. There was good correlation between DNAemia measurements in patient samples across dPCR platforms (r > 0.90 for each assay and matrix).

CONCLUSION

dPCR can quantify low-level herpes virus DNAemia with CVs below 8 %. Our results indicate that using serum-derived cell-free DNA and droplet-based dPCR is optimal for quantitating low-level viral DNAemia; however, plasma and chip-based approaches are acceptable alternatives and suitable for epidemiologic investigation.

A Baseline Cellular Antiviral State Is Maintained by cGAS and Its Most Frequent Naturally Occurring Variant rs610913

Upon recognition of aberrantly located DNA, the innate immune sensor cyclic GMP-AMP synthase (cGAS) activates stimulator of IFN genes (STING)/IFN regulatory factor (IRF)3-driven antiviral responses. In this study, we characterized the ability of a specific variant of the human cGAS-encoding gene MB21D1, rs610913, to alter cGAS-mediated DNA sensing and viral infection. rs610913 is a frequent G>T polymorphism resulting in a P261H exchange in the cGAS protein. Data from the International Collaboration for the Genomics of HIV suggested that rs610913 nominally associates with HIV-1 acquisition in vivo. Molecular modeling of cGAS(P261H) hinted toward the possibility for an additional binding site for a potential cellular cofactor in cGAS dimers. However, cGAS(wild-type [WT]) or cGAS(P261H)-reconstituted THP-1 cGAS knockout cells shared steady-state expression of IFN-stimulated genes, as opposed to cells expressing the enzymatically inactive cGAS(G212A/S213A). Accordingly, cGAS(WT) and cGAS(P261H) cells were less susceptible to lentiviral transduction and infection with HIV-1, HSV-1, and Chikungunya virus as compared with cGAS knockout or cGAS(G212A/S213A) cells. Upon DNA challenge, innate immune activation appeared to be mildly reduced upon expression of cGAS(P261H) compared with cGAS(WT). Finally, DNA challenge of PBMCs from donors homozygously expressing rs610913 provoked a trend toward a slightly reduced type I IFN response as compared with PBMCs from GG donors. Taken together, the steady-state activity of cGAS maintains a baseline antiviral state rendering cells more refractory to IFN-stimulated gene-sensitive viral infections. rs610913 failed to grossly differ phenotypically from the WT gene, suggesting that cGAS(P261H) and WT cGAS share a similar ability to sense viral infections in vivo.

The interferon-inducible GTPase MxB promotes capsid disassembly and genome release of herpesviruses

Host proteins sense viral products and induce defence mechanisms, particularly in immune cells. Using cell-free assays and quantitative mass spectrometry, we determined the interactome of capsid-host protein complexes of herpes simplex virus and identified the large dynamin-like GTPase myxovirus resistance protein B (MxB) as an interferon-inducible protein interacting with capsids. Electron microscopy analyses showed that cytosols containing MxB had the remarkable capability to disassemble the icosahedral capsids of herpes simplex viruses and varicella zoster virus into flat sheets of connected triangular faces. In contrast, capsids remained intact in cytosols with MxB mutants unable to hydrolyse GTP or to dimerize. Our data suggest that MxB senses herpesviral capsids, mediates their disassembly, and thereby restricts the efficiency of nuclear targeting of incoming capsids and/or the assembly of progeny capsids. The resulting premature release of viral genomes from capsids may enhance the activation of DNA sensors, and thereby amplify the innate immune responses.

Human Herpesvirus 6 (HHV-6) Encephalitis in a Non-Transplant Patient With Polymyositis

Human herpesvirus 6 (HHV-6) was initially labeled as a human B lymphotropic virus because it was isolated in patients diagnosed with lymphoproliferative disorders. There are two variants of HHV-6: HHV-6A and HHV-6B. A considerable majority of recorded primary infections and reactivation events are primarily due to HHV-6B. We report a case of HHV-6 encephalitis reactivation in a 75-year-old Caucasian diabetic female with a past medical history of polymyositis treated with prednisone for a long time who presented with generalized weakness and drowsiness. She developed her symptoms after contact with her grandchildren, who recently had viral-like symptoms treated with antibiotics. Magnetic resonance imaging (MRI) of the brain without contrast showed 14 mm high transverse relaxation time (T2)/fluid-attenuated inversion recovery (FLAIR) signal intensity focus on the left temporal lobe, suspicious for primary versus metastatic neoplasm. Cerebrospinal fluid analysis found that protein concentration was 75 mg/dl, glucose concentration 55 mg/dl, white blood cell count was 22/mm3, with a lymphocytic predominance. Meningitis/encephalitis polymerase chain reaction (PCR) panel detected HHV-6. She was discharged after treatment with ganciclovir for 14 days. It is crucial to recognize HHV-6 infections in immunocompromised patients who present with a T2/FLAIR signal intensity focus in the left temporal lobe. In a hospital setting, rapid HHV-6 encephalitis testing is important to make a correct diagnosis to avoid any delay to prevent further morbidity and mortality.

Herpes DNAemia and TTV Viraemia in Intensive Care Unit Critically Ill Patients: A Single-Centre Prospective Longitudinal Study

Introduction

We analysed blood DNAemia of TTV and four herpesviruses (CMV, EBV, HHV6, and HSV-1) in the REAnimation Low Immune Status Marker (REALISM) cohort of critically ill patients who had presented with either sepsis, burns, severe trauma, or major surgery. The aim was to identify common features related to virus and injury-associated pathologies and specific features linking one or several viruses to a particular pathological context.

Methods

Overall and individual viral DNAemia were measured over a month using quantitative PCR assays from the 377 patients in the REALISM cohort. These patients were characterised by clinical outcomes [severity scores, mortality, Intensive Care Unit (ICU)-acquired infection (IAI)] and 48 parameters defining their host response after injury (cell populations, immune functional assays, and biomarkers). Association between viraemic event and clinical outcomes or immune markers was assessed using χ²-test or exact Fisher’s test for qualitative variables and Wilcoxon test for continuous variables.

Results

The cumulative incidence of viral DNAemia increased from below 4% at ICU admission to 35% for each herpesvirus during the first month. EBV, HSV1, HHV6, and CMV were detected in 18%, 12%, 10%, and 9% of patients, respectively. The incidence of high TTV viraemia (>10,000 copies/ml) increased from 11% to 15% during the same period. Herpesvirus viraemia was associated with severity at admission; CMV and HHV6 viraemia correlated with mortality during the first week and over the month. The presence of individual herpesvirus during the first month was significantly associated (p < 0.001) with the occurrence of IAI, whilst herpesvirus DNAemia coupled with high TTV viraemia during the very first week was associated with IAI. Herpesvirus viraemia was associated with a lasting exacerbated host immune response, with concurrent profound immune suppression and hyper inflammation, and delayed return to immune homeostasis. The percentage of patients presenting with herpesvirus DNAemia was significantly higher in sepsis than in all other groups. Primary infection in the hospital and high IL10 levels might favour EBV and CMV reactivation.

Conclusion

In this cohort of ICU patients, phenotypic differences were observed between TTV and herpesviruses DNAemia. The higher prevalence of herpesvirus DNAemia in sepsis hints at further studies that may enable a better in vivo understanding of host determinants of herpesvirus viral reactivation. Furthermore, our data suggest that EBV and TTV may be useful as additional markers to predict clinical deterioration in ICU patients.

Absence of cGAS-mediated type I IFN responses in HIV-1-infected T cells

The DNA sensor cGAS catalyzes the production of the cyclic dinucleotide cGAMP, resulting in type I interferon responses. We addressed the functionality of cGAS-mediated DNA sensing in human and murine T cells. Activated primary CD4+ T cells expressed cGAS and responded to plasmid DNA by upregulation of ISGs and release of bioactive interferon. In mouse T cells, cGAS KO ablated sensing of plasmid DNA, and TREX1 KO enabled cells to sense short immunostimulatory DNA. Expression of IFIT1 and MX2 was downregulated and upregulated in cGAS KO and TREX1 KO T cell lines, respectively, compared to parental cells. Despite their intact cGAS sensing pathway, human CD4+ T cells failed to mount a reverse transcriptase (RT) inhibitor-sensitive immune response following HIV-1 infection. In contrast, infection of human T cells with HSV-1 that is functionally deficient for the cGAS antagonist pUL41 (HSV-1ΔUL41N) resulted in a cGAS-dependent type I interferon response. In accordance with our results in primary CD4+ T cells, plasmid challenge or HSV-1ΔUL41N inoculation of T cell lines provoked an entirely cGAS-dependent type I interferon response, including IRF3 phosphorylation and expression of ISGs. In contrast, no RT-dependent interferon response was detected following transduction of T cell lines with VSV-G-pseudotyped lentiviral or gammaretroviral particles. Together, T cells are capable to raise a cGAS-dependent cell-intrinsic response to both plasmid DNA challenge or inoculation with HSV-1ΔUL41N. However, HIV-1 infection does not appear to trigger cGAS-mediated sensing of viral DNA in T cells, possibly by revealing viral DNA of insufficient quantity, length, and/or accessibility to cGAS.

Herpes Simplex Virus Type 1 Propagation, Titration and Single-step Growth Curves

Given the endemic seroprevalence of herpes simplex viruses (HSV), its associated human diseases, and the emergence of acyclovir-resistant strains, there is a continuous need for better antiviral therapies. Towards this aim, identifying mechanistic details of how HSV-1 manipulates infected cells, how it modulates the immune responses, and how it causes diseases are essential. Measuring titers and growth kinetics of clinical isolates and viral mutants are important for a thorough characterization of viral phenotypes in vitro and in vivo. We provide protocols for the preparation as well as titration of HSV-1 stocks, and explain how to perform single-step growth curves to characterize the functions of viral proteins or host factors during infection. In particular, we describe methods to prepare and characterize high-titer HSV-1 stocks with low genome to titer ratios that are required for infection studies in cell culture and animal experiments.

Varicella zoster virus infections in neurological patients: a clinical study

Background

Varicella zoster virus (VZV) reactivation is a common infectious disease in neurology and VZV the second most frequent virus detected in encephalitis. This study investigated characteristics of clinical and laboratory features in patients with VZV infection.

Methods

Two hundred eighty two patients with VZV reactivation that were hospitalized in the department of neurology in the time from 2005 to 2013 were retrospectively evaluated. Results from cerebrospinal fluid (CSF) analysis were available from 85 patients.

Results

Trigeminal rash was the most common clinical manifestation, followed by segmental rash, CNS infection, facial nerve palsy, postherpetic neuralgia, and radiculitis. MRI of the brain performed in 25/33 patients with encephalitis/meningitis did not show any signs of infection in the brain parenchyma. Only one patient showed contrast enhancement in the hypoglossal nerve. General signs of infection such as fever or elevated CRP values were found in only half of the patients. Furthermore, rash was absent in a quarter of patients with CNS infection and facial nerve palsy, and thus, infection could only be proven by CSF analysis. Although slight inflammatory CSF changes occurred in few patients with isolated rash, the frequency was clearly higher in patients with CNS infection and facial nerve palsy.

Conclusion

Monosegmental herpes zoster is often uncomplicated and a diagnostic lumbar puncture is not essential. In contrast, CSF analysis is an essential diagnostic tool in patients with skin lesions and cranial nerve or CNS affection. In patients with neuro-psychiatric symptoms and inflammatory CSF changes analysis for VZV should be performed even in the absence of skin lesions.

Human Herpesviruses 6A, 6B, and 7

Human roseoloviruses include three different species, human herpesviruses 6A, 6B, and 7 (HHV-6A, HHV-6B, HHV-7), genetically related to human cytomegalovirus. They exhibit a wide cell tropism in vivo and, like other herpesviruses, induce a lifelong latent infection in humans. In about 1% of the general population, HHV-6 DNA is covalently integrated into the subtelomeric region of cell chromosomes (ciHHV-6). Many active infections, corresponding to primary infections, reactivations, or exogenous reinfections, are asymptomatic. They also may cause serious diseases, particularly in immunocompromised individuals, including hematopoietic stem-cell transplant (HSCT) and solid-organ transplant recipients, and acquired immunodeficiency syndrome (AIDS) patients. This opportunistic pathogenic role is formally established for HHV-6 infection and less clear for HHV-7. It mainly concerns the central-nervous system, bone marrow, lungs, gastrointestinal tract, skin, and liver. As the best example, HHV-6 causes both exanthema subitum, a benign disease associated with primary infection, and severe encephalitis associated with virus reactivations in HSCT recipients. Diagnosis using serologic and direct antigen-detection methods currently exhibits limitations. The most prominent technique is the quantification of viral DNA in blood, other body fluids, and organs by means of real-time polymerase-chain reaction (PCR). The antiviral compounds ganciclovir, foscarnet, and cidofovir are effective against active infections, but there is currently no consensus regarding the indications of treatment or specifics of drug administration. Numerous questions about HHV-6A, HHV-6B, HHV-7 are still pending, concerning in particular clinical impact and therapeutic options in immunocompromised patients.

Herpes Simplex Virus and Varicella-Zoster Virus

The most common specimens from immunocompromised patients that are analyzed for detection of herpes simplex virus (HSV) or varicella-zoster virus (VZV) are from skin lesions. Many types of assays are applicable to these samples, but some, such as virus isolation and direct fluorescent antibody testing, are useful only in the early phases of the lesions. In contrast, nucleic acid (NA) detection methods, which generally have superior sensitivity and specificity, can be applied to skin lesions at any stage of progression. NA methods are also the best choice, and sometimes the only choice, for detecting HSV or VZV in blood, cerebrospinal fluid, aqueous or vitreous humor, and from mucosal surfaces. NA methods provide the best performance when reliability and speed (within 24 hours) are considered together. They readily distinguish the type of HSV detected or the source of VZV detected (wild type or vaccine strain). Nucleic acid detection methods are constantly being improved with respect to speed and ease of performance. Broader applications are under study, such as the use of quantitative results of viral load for prognosis and to assess the efficacy of antiviral therapy.

European consensus-based (S2k) Guideline on the Management of Herpes Zoster - guided by the European Dermatology Forum (EDF) in cooperation with the European Academy of Dermatology and Venereology (EADV), Part 1: Diagnosis

Herpes zoster (HZ, shingles) is a frequent medical condition which may severely impact the quality of life of affected patients. Different therapeutic approaches to treat acute HZ are available. The aim of this European project was the elaboration of a consensus-based guideline on the management of patients who present with HZ, considering different patient populations and different localizations. This interdisciplinary guideline aims at an improvement of the outcomes of the acute HZ management concerning disease duration, acute pain and quality of life of the affected patients and at a reduction of the incidence of postherpetic neuralgia and other complications. The guideline development followed a structured and predefined process, considering the quality criteria for guidelines development as suggested by the AGREE II instrument. The steering group was responsible for the planning and the organization of the guideline development process (Division of Evidence based Medicine, dEBM). The expert panel was nominated by virtue of clinical expertise and/or scientific experience and included experts from the fields of dermatology, virology/infectiology, ophthalmology, otolaryngology, neurology and anaesthesiology. Recommendations for clinical practice were formally consented during the consensus conference, explicitly considering different relevant aspects. The guideline was approved by the commissioning societies after an extensive internal and external review process. In this first part of the guideline, diagnostic means have been evaluated. The expert panel formally consented recommendations for the management of patients with (suspected) HZ, referring to the assessment of HZ patients, considering various specific clinical situations. Users of the guideline must carefully check whether the recommendations are appropriate for the context of intended application. In the setting of an international guideline, it is generally important to consider different national approaches and legal circumstances with regard to the regulatory approval, availability and reimbursement of diagnostic and therapeutic interventions.

Microbiology laboratory and the management of mother-child varicella-zoster virus infection

Varicella-zoster virus, which is responsible for varicella (chickenpox) and herpes zoster (shingles), is ubiquitous and causes an acute infection among children, especially those aged less than six years. As 90% of adults have had varicella in childhood, it is unusual to encounter an infected pregnant woman but, if the disease does appear, it can lead to complications for both the mother and fetus or newborn. The major maternal complications include pneumonia, which can lead to death if not treated. If the virus passes to the fetus, congenital varicella syndrome, neonatal varicella (particularly serious if maternal rash appears in the days immediately before or after childbirth) or herpes zoster in the early years of life may occur depending on the time of infection. A Microbiology laboratory can help in the diagnosis and management of mother-child infection at four main times: (1) when a pregnant woman has been exposed to varicella or herpes zoster, a prompt search for specific antibodies can determine whether she is susceptible to, or protected against infection; (2) when a pregnant woman develops clinical symptoms consistent with varicella, the diagnosis is usually clinical, but a laboratory can be crucial if the symptoms are doubtful or otherwise unclear (atypical patterns in immunocompromised subjects, patients with post-vaccination varicella, or subjects who have received immunoglobulins), or if there is a need for a differential diagnosis between varicella and other types of dermatoses with vesicle formation; (3) when a prenatal diagnosis of uterine infection is required in order to detect cases of congenital varicella syndrome after the onset of varicella in the mother; and (4) when the baby is born and it is necessary to confirm a diagnosis of varicella (and its complications), make a differential diagnosis between varicella and other diseases with similar symptoms, or confirm a causal relationship between maternal varicella and malformations in a newborn.

Using Patient-Specific Induced Pluripotent Stem Cells and Wild-Type Mice to Develop a Gene Augmentation-Based Strategy to Treat CLN3-Associated Retinal Degeneration

Juvenile neuronal ceroid lipofuscinosis (JNCL) is a childhood neurodegenerative disease with early-onset, severe central vision loss. Affected children develop seizures and CNS degeneration accompanied by severe motor and cognitive deficits. There is no cure for JNCL, and patients usually die during the second or third decade of life. In this study, independent lines of induced pluripotent stem cells (iPSCs) were generated from two patients with molecularly confirmed mutations in CLN3, the gene mutated in JNCL. Clinical-grade adeno-associated adenovirus serotype 2 (AAV2) carrying the full-length coding sequence of human CLN3 was generated in a U.S. Food and Drug Administration-registered cGMP facility. AAV2-CLN3 was efficacious in restoring full-length CLN3 transcript and protein in patient-specific fibroblasts and iPSC-derived retinal neurons. When injected into the subretinal space of wild-type mice, purified AAV2-CLN3 did not show any evidence of retinal toxicity. This study provides proof-of-principle for initiation of a clinical trial using AAV-mediated gene augmentation for the treatment of children with CLN3-associated retinal degeneration.

Optical micro-particle size detection by phase-generated carrier demodulation

We demonstrate an optical micro-particle size detection technique based on phase sensing by a fiber interferometer through phase-generated carrier (PGC) modulation/demodulation. Particle diameters were resolved from phase shift due to particle-induced optical scattering. Polystyrene nanoparticles, air bubbles and yeast cells in a microfluidic channel were tested using this technique, and particle diameters ranging from 0.7 to 5.5 μm can be resolved in real-time. In comparison with existing amplitude-sensing techniques which require tens of milliwatts of laser irradiance, phase-sensing through PGC can successfully utilize probe laser powers as low as 220 μW to measure the test particle sizes. We further constructed a theoretical model based on phase scattering and PGC demodulation, which obtained good agreement between experimental data and calculated phase shift as a function of particle time-of-flight. This technique may be applied to a wide range of potential applications, ranging from real-time analysis of clinically relevant cell samples, to contamination control of processing fluids used in the semiconductor industry.

Development of a multiplex real-time PCR for the simultaneous detection of herpes simplex and varicella zoster viruses in cerebrospinal fluid and lesion swab specimens

Herpes simplex viruses (HSV) and varicella zoster virus (VZV) can have very similar and wide-ranging clinical presentations. Rapid identification is necessary for timely antiviral therapy, especially with infections involving the central nervous system, neonates, and immunocompromised individuals. Detection of HSV-1, HSV-2 and VZV was combined into one real-time PCR reaction utilizing hydrolysis probes. The assay was validated on the LightCycler(®) (Roche) and Applied Biosystems 7500 Real-Time PCR System (Thermo Fisher Scientific Inc.) to detect alphaherpesviruses in cerebral spinal fluid (CSF) and lesion swab specimens, respectively. Validation data on blood and tissue samples are also presented. The multiplex assay showed excellent sensitivity, specificity and reproducibility when compared to two singleplex real-time PCR assays for CSF samples and direct fluorescent antigen/culture for lesion swab samples. Implementation of the multiplex assay has facilitated improved sensitivity and accuracy as well as reduced turn-around-times and costs. The results from a large data set of 16,622 prospective samples tested between August 16, 2012 to February 1, 2014 at the Provincial Laboratory for Public Health (Alberta, Canada) are presented here.

Long-term impact of CMV infection on allografts and on patient survival in renal transplant patients with protocol biopsies

Cytomegalovirus (CMV) infection is a frequent complication of early posttransplantation. This study examines its impact on chronic allograft changes, long-term graft loss, and patient survival. We studied 594 patients who had protocol biopsies at 6 wk, and 3 and 6 mo posttransplantation. Chronic allograft changes were evaluated according to the updated Banff classification [interstitial fibrosis/tubular atrophy (IF/TA), vascular and glomerular lesions]. Follow-up data were available for up to 10 yr. CMV infection was diagnosed in 153 of 594 patients (26%) in the first year after transplantation, mostly within the first 3 mo. Graft survival was reduced in patients with CMV ( P = 0.03) as well as the combined allograft/patient survival ( P = 0.008). Prevalence of IF/TA at 6 wk after transplantation was already threefold higher in patients who experienced CMV infection later on compared with patients without CMV ( P = 0.005). In multivariate analyses, CMV viremia or disease was not a significant factor for graft loss or death. In conclusion, patients with CMV infection posttransplantation show more chronic allograft changes early on, even before CMV infection, and development of IF/TA is not more prevalent in patients with CMV. Our data do not support a significant role of CMV in patient and graft outcomes.

Integrating between-host transmission and within-host immunity to analyze the impact of varicella vaccination on zoster

Varicella-zoster virus (VZV) causes chickenpox and reactivation of latent VZV causes herpes zoster (HZ). VZV reactivation is subject to the opposing mechanisms of declining and boosted VZV-specific cellular mediated immunity (CMI). A reduction in exogenous re-exposure ‘opportunities’ through universal chickenpox vaccination could therefore lead to an increase in HZ incidence. We present the first individual-based model that integrates within-host data on VZV-CMI and between-host transmission data to simulate HZ incidence. This model allows estimating currently unknown pivotal biomedical parameters, including the duration of exogenous boosting at 2 years, with a peak threefold to fourfold increase of VZV-CMI; the VZV weekly reactivation probability at 5% and VZV subclinical reactivation having no effect on VZV-CMI. A 100% effective chickenpox vaccine given to 1 year olds would cause a 1.75 times peak increase in HZ 31 years after implementation. This increase is predicted to occur mainly in younger age groups than is currently assumed.

DOI:http://dx.doi.org/10.7554/eLife.07116.001

The itchy-scratchy misery of a chickenpox was until recently a rite of passage for children around the world. The varicella-zoster virus causes chickenpox infections. This virus persists in small numbers in nerve cells for many years after infection, and can reactivate from these cells. Often this reactivation causes no symptoms, but sometimes it results in a painful skin condition called shingles (or herpes zoster), especially in older adults.

Some countries—including the United States, Australia, Taiwan and Greece—have virtually wiped out childhood cases of chickenpox by requiring that children be vaccinated against the varicella-zoster virus. But some countries have hesitated. One reason for this hesitation is that exposure to individuals with a chickenpox infection helps boost the immunity of individuals who have previously been infected. This may help reduce the likelihood of these people developing shingles later in life. So, some countries have worried that chickenpox vaccinations might inadvertently increase the number of shingles cases. To assess this risk, many scientists have created computer models, but the models have some limitations.

Now, Ogunjimi et al. report a new individual-based model to assess the effect of childhood varicella vaccination on shingles cases that factors in the immune responses to varicella infection. The model suggests that re-exposure to the varicella virus through contact with infected people would only provide extra protection for about two years; this is much shorter than previous predictions that suggested it might last 20 years. The model also predicts that implementing a varicella vaccination program for children would almost double the number of shingles cases 31 years later. But this increase would be temporary.

The predicted increase in shingles cases is likely to disproportionately occur among 31- to 40-year-olds. This is unexpected because most previous models predict that older age groups would bear the brunt of a rise in shingles, but this younger population would be less likely to develop lasting complications of shingles. Together, these findings may allay some fears about implementing childhood varicella vaccination programs by showing that the benefits of re-exposure are limited.

DOI:http://dx.doi.org/10.7554/eLife.07116.002

Varicella Zoster Virus Meningitis in a Young Immunocompetent Adult without Rash: A Misleading Clinical Presentation

Meningitis caused by varicella zoster virus (VZV) is rare in healthy population. Predominantly immunocompromised patients are affected by reactivation of this virus with primary clinical features of rash and neurological symptoms. Here we report a young otherwise healthy man diagnosed with a VZV meningitis without rash. He complained of acute headache, nausea, and vomiting. The clinical examination did not show any neurological deficits or rash. Cerebrospinal fluid (CSF) analysis revealed a high leukocyte cell count of 1720 cells/µL and an elevated total protein of 1460 mg/L misleadingly indicating a bacterial infection. Further CSF analyses, including polymerase chain reaction (PCR) and detection of intrathecal synthesis of antibodies, showed a VZV infection. Clinical and CSF follow-up examinations proved the successful antiviral treatment. In conclusion, even young immunocompetent patients without rash might present with VZV meningitis. CSF examination is a key procedure in the diagnosis of CNS infections but in rare cases the standard values cell count and total protein might misleadingly indicate a bacterial infection. Thus, virological analyses should be considered even when a bacterial infection is suspected.

Herpes simplex virus internalization into epithelial cells requires Na+/H+ exchangers and p21-activated kinases but neither clathrin- nor caveolin-mediated endocytosis

Herpes simplex virus 1 (HSV-1) is an alphaherpesvirus that has been reported to infect some epithelial cell types by fusion at the plasma membrane but others by endocytosis. To determine the molecular mechanisms of productive HSV-1 cell entry, we perturbed key endocytosis host factors using specific inhibitors, RNA interference (RNAi), or overexpression of dominant negative proteins and investigated their effects on HSV-1 infection in the permissive epithelial cell lines Vero, HeLa, HEp-2, and PtK2. HSV-1 internalization required neither endosomal acidification nor clathrin- or caveolin-mediated endocytosis. In contrast, HSV-1 gene expression and internalization were significantly reduced after treatment with 5-(N-ethyl-N-isopropyl)amiloride (EIPA). EIPA blocks the activity of Na(+)/H(+) exchangers, which are plasma membrane proteins implicated in all forms of macropinocytosis. HSV-1 internalization furthermore required the function of p21-activated kinases that contribute to macropinosome formation. However, in contrast to some forms of macropinocytosis, HSV-1 did not enlist the activities of protein kinase C (PKC), tyrosine kinases, C-terminal binding protein 1, or dynamin to activate its internalization. These data suggest that HSV-1 depends on Na(+)/H(+) exchangers and p21-activated kinases either for macropinocytosis or for local actin rearrangements required for fusion at the plasma membrane or subsequent passage through the actin cortex underneath the plasma membrane.

IMPORTANCE

After initial replication in epithelial cells, herpes simplex viruses (HSVs) establish latent infections in neurons innervating these regions. Upon primary infection and reactivation from latency, HSVs cause many human skin and neurological diseases, particularly in immunocompromised hosts, despite the availability of effective antiviral drugs. Many viruses use macropinocytosis for virus internalization, and many host factors mediating this entry route have been identified, although the specific perturbation profiles vary for different host and viral cargo. In addition to an established entry pathway via acidic endosomes, we show here that HSV-1 internalization depended on sodium-proton exchangers at the plasma membrane and p21-activated kinases. These results suggest that HSV-1 requires a reorganization of the cortical actin cytoskeleton, either for productive cell entry via pH-independent fusion from macropinosomes or for fusion at the plasma membrane, and subsequent cytosolic passage to microtubules that mediate capsid transport to the nucleus for genome uncoating and replication.

Enrichment of nanoparticles and bacteria using electroless and manual actuation modes of a bypass nanofluidic device

Current efforts in nanofluidics aimed at detecting scarce molecules or particles are focused mainly on the development of electrokinetic-based devices. However, these techniques require either integrated or external electrodes, and a potential drop applied across a carrier fluid. One challenge is to develop a new generation of electroless passive devices involving a simple technological process and packaging without embedded electrodes for micro- and nanoparticles enrichment with a view to applications in biology such as the detection of viral agents or cancers biomarkers. This paper presents an innovative technique for particles handling and enrichment based exclusively on a pressure-driven silicon bypass nanofluidic device. The device is fabricated by standard silicon micro-nanofabrication technology. The concentration operation was demonstrated and quantified according to two different actuation modes, which can also be combined to enhance the concentration factor further. The first, "symmetrical" mode involves a symmetric cross-flow effect that concentrates nanoparticles in a very small volume in a very local point of the device. The second mode, "asymmetrical" mode advantageously generates a streaming potential, giving rise to an Electroless Electropreconcentration (EL-EP). The concentration process can be maintained for several hours and concentration factors as high as ~200 have been obtained when both symmetrical and asymmetrical modes are coupled. Proof of concept for concentrating E. coli bacteria by the manual actuation of the EL-EP device is also demonstrated in this paper. Experiments demonstrate more than a 50-fold increase in the concentration of E. coli bacteria in only ~40 s.

Chronic lymphocytic leukemia patients have a preserved cytomegalovirus-specific antibody response despite progressive hypogammaglobulinemia

Chronic lymphocytic leukemia (CLL) is characterized by progressive hypogammaglobulinemia predisposing affected patients to a variety of infectious diseases but paradoxically not to cytomegalovirus (CMV) disease. Moreover, we found reactivity of a panel of CLL recombinant antibodies (CLL-rAbs) encoded by a germ-line allele with a single CMV protein, pUL32, despite differing antibody binding motifs. To put these findings into perspective, we studied prospectively relative frequency of viremia, kinetics of total and virus-specific IgG over time, and UL32 genetic variation in a cohort of therapy-naive patients (n=200). CMV-DNA was detected in 3% (6/200) of patients. The decay of total IgG was uniform (mean, 0.03; SD, 0.03) and correlated with that of IgG subclasses 1-4 in the paired samples available (n=64; p<0.001). Total CMV-specific IgG kinetics were more variable (mean, 0,02; SD, 0,06) and mean decay values differed significantly from those of total IgG (p=0.034). Boosts of CMV-specific antibody levels were observed in 49% (22/45) of CMV-seropositive patients. In contrast, VZV- and EBV-specific IgG levels decayed in parallel with total IgG levels (p=0.003 and p=0.001, respectively). VZV-specific IgG even became undetectable in 18% (9/50) of patients whereas CMV-specific ones remained detectable in all seropositive patients. The observed CMV-specific IgG kinetics were predicated upon the highly divergent kinetics of IgG specific for individual antigens - glycoprotein B-specific IgG were boosted in 51% and pUL32-specific IgG in 32% of patients. In conclusion, CLL patients have a preserved CMV-specific antibody response despite progressive decay of total IgG and IgG subclasses. CMV-specific IgG levels are frequently boosted in contrast to that of other herpesviruses indicative of a higher rate of CMV reactivation and antigen-presentation. In contrast to the reactivity of multiple different CLL-rAbs with pUL32, boosts of humoral immunity are triggered apparently by other CMV antigens than pUL32, like glycoprotein B.

Calibrated real-time polymerase chain reaction for specific quantitation of HHV-6A and HHV-6B in clinical samples

The recent classification of human herpesvirus 6 (HHV-6) A and B, previously considered as two variants of the same virus, as two distinct herpesvirus species, emphasizes the need to develop and standardize specific methods for their detection and quantitation for clinical use. The development of two highly sensitive calibrated real-time PCR to quantify HHV-6A and -6B variants in clinical specimen is described. Both assays displayed the same wide linear dynamic range from 10(0) to 10(6) copies of viral DNA in a single reaction and sensitivity of one copy/reaction. These systems allow for HHV-6A/B DNA load quantitation in different types of clinical specimens: blood or tissue cells when combined with the CCR5 assay; cell-free samples (plasma or other biological fluids) in combination with the calibrator technology. Due to the absence of cross-amplification and cross-hybridization, these methods detect minute amounts of one viral species even in the presence of a large excess of the other, allowing a specific quantitation of both viruses in the case of mixed infections. The new qPCR methods provide sensitive and specific tool for monitoring HHV-6A/B DNA load in clinical samples, facilitating the study of these viruses in human diseases.

Viremia after lung transplant: a cohort study on risk factors and symptoms associated with detection of Epstein-Barr virus

Background-The frequency and impact of detection of Epstein-Barr virus in the blood of lung and heart-lung transplant recipients in the postoperative period is poorly characterized.Objective-To investigate the frequency of virus detection, associated clinical symptoms and risk factors, and influence of virus detection on outcome.Methods-A cohort of 98 lung transplant recipients were monitored for Epstein-Barr virus in blood before transplant and during their posttransplant hospital stay (median 4 weeks, range 1-21 weeks). Patients were followed up for retransplant or death for a median of 17 months.Results-Epstein-Barr virus DNA was detected in 15 recipients (18.1%) before and in 39 recipients (41.5%) after transplant. Median viral load after transplant was 2300 copies per milliliter of blood (range, 900-45 000 copies/mL). Detection of Epstein-Barr virus DNA before transplant and mechanical ventilation before transplant were associated with detection of Epstein-Barr virus DNA after transplant. Shortness of breath, fatigue, and hoarseness were associated with detection of viral DNA after transplant. The incidence of retransplant or death was not increased in recipients who had viral DNA detected in their blood.Conclusions-Epstein-Barr virus DNA in the blood before transplant and mechanical ventilation before transplant were associated with detection of viral DNA after transplant. Detection of viral DNA after transplant was frequent and clinically relevant.

Nanofluidic preconcentration and detection of nanoparticles

The fast detection and characterization of nanoparticles, such as viruses or environmental pollutants, are important in fields ranging from biosensing to quality control. However, most existing techniques have practical throughput limitations, which significantly limit their applicability to low analyte concentrations. Here, we present an integrated nanofluidic scheme for preconcentration and subsequent detection of nanoparticle samples within a continuous flow-through system. Using a Brownian ratchet mechanism, we increase the nanoparticle concentration ∼27-fold. Single nanoparticles are subsequently detected and characterized by optical heterodyne interferometry. A wide range of potential applications can be foreseen, including real-time analysis of clinically relevant virus samples and contamination control of processing fluids used in the semiconductor industry.

CXCL13 as a novel marker for diagnosis and disease monitoring in pediatric PTLD

Posttransplant lymphoproliferative disease (PTLD) is a severe complication of immunosuppressive treatment in organ-grafted children. Early diagnosis of PTLD is hampered by both unspecific clinical symptoms and lack of easy accessible markers. The homeostatic chemokine CXCL13, which plays a crucial role in B-cell homing and lymphoid organ development, is expressed in some lymphomatous diseases. This study aims to investigate whether serum CXCL13 (sCXCL13) levels correlate with occurrence and regression of PTLD in pediatric solid-organ graft recipients. Serum samples from PTLD patients (n = 21), patients with Epstein-Barr virus (EBV) reactivation (n = 18), and healthy age-matched controls (n = 19) were tested for CXCL13 using a commercially available ELISA kit. sCXCL13 levels were significantly higher in PTLD patients than in healthy children. PTLD patients had also higher sCXCL13 values than pediatric solid-organ recipients with EBV reactivation. An increase in sCXCL13 levels was observed from EBV reactivation to PTLD diagnosis in most cases. Elevated sCXCL13 levels were detected up to 2 years prior to PTLD diagnosis and correlated well with response to cytoreductive treatment in individual patients. sCXCL13, thus, may be a readily available surrogate marker for the diagnosis of PTLD and for monitoring of response to treatment in patients with initially elevated sCXCL13 levels.

High intrahepatic HHV-6 virus loads but neither CMV nor EBV are associated with decreased graft survival after diagnosis of graft hepatitis

BACKGROUND & AIMS

In liver transplant recipients with graft hepatitis, the relevance of herpesviruses is not well defined.

METHODS

Viral loads of CMV, EBV, and HHV-6 were determined in blood and liver biopsies of 170 liver transplant recipients with graft hepatitis by quantitative PCR.

RESULTS

HHV-6-, CMV-, and EBV-DNA were detected in 58%, 14%, and 44% of the biopsies, respectively, with coinfections in 34%. High intrahepatic HHV-6 DNA levels (>75th percentile, 11.27 copies/1000 cells) and detection of HHV-6 DNAemia were significantly associated with decreased graft survival after diagnosis of graft hepatitis (p=0.014 and p=0.003, respectively, median follow-up was 23.8 months). Multivariate analysis confirmed high intrahepatic HHV-6 loads as an independent factor associated with reduced graft survival (adjusted hazard ratio 2.61, 95%confidence interval 1.16-5.87). Low concentrations of HHV6 DNA in the liver, indicating latent infection, did not influence graft survival. Neither CMV nor EBV (qualitative detection and high virus loads) nor acute rejection (according to the BANFF score) affected graft survival. However, patients had been treated for CMV reactivations and acute rejections in this retrospective study. High age and high bilirubin levels were the other independent factors associated with reduced graft survival (adjusted hazard ratio 3.56CI 1.52-8.34 and 3.23CI 1.50-6.96, respectively).

CONCLUSIONS

High intrahepatic HHV-6-DNA levels are associated with decreased graft survival in liver transplant recipients with graft hepatitis. The significance of HHV-6 as potential etiology of graft hepatitis needs further evaluation.

Prolonged detection of herpes simplex virus type 2 (HSV-2) DNA in cerebrospinal fluid despite antiviral therapy in a patient with HSV-2-associated radiculitis

Herpes simplex virus type 2 (HSV-2) can cause radiculo-myelitis as a neurological manifestation. We report a case of ongoing HSV-2 DNA positivity in the cerebrospinal fluid (CSF) of at least eight weeks under antiviral therapy with acyclovir in a highly immunocompromised hemato-oncologic patient with HSV-2-associated radiculitis. Upon admission, the patient presented with pain, leg paresis, and urinary incontinence, as well as pleocytosis in the CSF. Quantitative real-time PCR of the CSF at day 3 after admission revealed HSV-2 with a concentration of 2.0×10(5) copies/ml and treatment with acyclovir intravenously and prednisolone by mouth was started. Clinical symptoms resolved almost completely after approximately 3 weeks of antiviral therapy. However, CSF samples of day 12, 19, 26, 33, 39, 48 and 54 after admission showed a slow decline of HSV-2 DNA concentrations. HSV-2 DNA was still detectable (1.6×10(4) copies/ml) at day 54 after admission. Genotypic resistance testing showed, as far as available, no mutations indicative for acyclovir resistance. Since an increasing specific antibody index for HSV was observed, we speculate that the prolonged detectability of HSV-2 DNA in the CSF might not necessarily indicate ongoing viral replication but neutralized virus. Other hypotheses and the consequences on treatment are discussed. To our knowledge this is the first report about the long-term viral load kinetics of HSV-2 in the CSF of a patient with radiculitis under antiviral therapy, highlighting the need for further studies on HSV DNA kinetics in the CSF and their significance for an appropriate antiviral treatment.

Real-time optical detection of single human and bacterial viruses based on dark-field interferometry

The rapid and sensitive detection and characterization of human viruses and bacteriophage is extremely important in a variety of fields, such as medical diagnostics, immunology and vaccine research, and environmental contamination and quality control. We introduce an optical detection scheme for real-time and label-free detection of human viruses and bacteriophage as small as ~24 nm in radius. Combining the advantages of heterodyne interferometry and dark-field microscopy, this label-free method enables us to detect and characterize various biological nanoparticles with unsurpassed sensitivity and selectivity. We demonstrate the high sensitivity and precision of the method by analyzing a mixture containing HIV virus and bacteriophage. The method also resolves the distribution of small nano-impurities (~20-30 nm) in clinically relevant virus samples.

Impact of CMV infection on acute rejection and long-term renal allograft function: a systematic analysis in patients with protocol biopsies and indicated biopsies

BACKGROUND

Higher rates of acute rejection (AR) and reduced graft survival have been reported in patients with cytomegalovirus (CMV) infection, but an association between these factors remains controversial.

METHODS

In this study, serial protocol biopsies (PBs) and clinically indicated biopsies (IBs) from a large cohort of renal allograft recipients (n &frac14; 594) were analyzed to examine the relation between CMV and AR.

RESULTS

Patients with CMV were more likely to receive IB (85 of the 153 patients; 56%) compared to patients without CMV (138 of 441 patients; 32%; P = 0.003). However, this did not translate into a greater number of patients with episodes of acute cellular rejection on histopathology in IBs. Analysis of PBs revealed a significantly higher number of episodes of rejection per patient with CMV infection (P = 0.04), but only in a subgroup of patients with triple immunosuppression. Long-term graft function post-transplantation was analyzed in four different subgroups according to CMV infection and/or AR. Differences in renal function were apparent within the first 6 weeks after transplantation and persisted during follow-up, with the best renal function in patients without AR or CMV, whereas patients with both AR and CMV had the worst (P < 0.012 at 1 year; P < 0.001 at 2 years). On average, the latter group had significantly older donors and more often delayed graft function.

CONCLUSIONS

Our data suggests that the link between CMV and AR is far less significant than previously thought. Outcome in patients with CMV may be more determined by coexisting conditions like high donor age and delayed graft function.

PCR detection of multiple human herpesvirus DNA in saliva from HIV-infected individuals in Teresina, State of Piauí, Brazil

INTRODUCTION: Human herpesviruses are frequently associated with orofacial diseases in humans (HSV-1, EBV, CMV and HHV-8), some can also cause systemic disease (CMV and HHV-8). The transmission of these viruses occurs by contact with infected secretions, especially saliva. Human immunodeficiency virus infection is associated with an increased risk of HHVs and related diseases. METHODS: This work aimed to detect HSV-1, EBV, CMV and HHV-8 DNA in saliva of HIV-infected patients from Teresina, northeast Brazil, by PCR and compare these findings with age and sex matched HIV-seronegative individuals. RESULTS: No difference in prevalence was verified between HHV detection in the saliva of HIV-seropositive individuals and controls. The individual frequencies of these viruses in these two populations were different. HIV seropositivity correlated positively with the presence of CMV (OR: 18.2, p= 0.00032) and EBV (OR: 3.44, p= 0.0081). No association between CD4 counts and the prevalence of HHVs in the saliva was observed; however, a strong association was determined between seropositivity and the presence of multiple HHV DNAs in saliva (OR: 4.83, p = 0.0028). CONCLUSIONS: These findings suggest the asymptomatic salivary shedding of HHVs is a common event between HIV-seropositive and seronegative individuals from Teresina, Piauí, Brazil, and, especially for HIV-seropositive patients, saliva is a risk factor for the acquisition/transmission of multiple HHVs.

Measurement of Epstein-Barr virus DNA load using a novel quantification standard containing two EBV DNA targets and SYBR Green I dye

Background

Reactivation of Epstein-Barr virus (EBV) infection may cause serious, life-threatening complications in immunocompromised individuals. EBV DNA is often detected in EBV-associated disease states, with viral load believed to be a reflection of virus activity. Two separate real-time quantitative polymerase chain reaction (QPCR) assays using SYBR Green I dye and a single quantification standard containing two EBV genes, Epstein-Barr nuclear antigen-1 (EBNA-1) and BamHI fragment H rightward open reading frame-1 (BHRF-1), were developed to detect and measure absolute EBV DNA load in patients with various EBV-associated diseases. EBV DNA loads and viral capsid antigen (VCA) IgG antibody titres were also quantified on a population sample.

Results

EBV DNA was measurable in ethylenediaminetetraacetic acid (EDTA) whole blood, peripheral blood mononuclear cells (PBMCs), plasma and cerebrospinal fluid (CSF) samples. EBV DNA loads were detectable from 8.0 × 10² to 1.3 × 10⁸ copies/ml in post-transplant lymphoproliferative disease (n = 5), 1.5 × 10³ to 2.0 × 10⁵ copies/ml in infectious mononucleosis (n = 7), 7.5 × 10⁴ to 1.1 × 10⁵ copies/ml in EBV-associated haemophagocytic syndrome (n = 1), 2.0 × 10² to 5.6 × 10³ copies/ml in HIV-infected patients (n = 12), and 2.0 × 10² to 9.1 × 10⁴ copies/ml in the population sample (n = 218). EBNA-1 and BHRF-1 DNA were detected in 11.0% and 21.6% of the population sample respectively. There was a modest correlation between VCA IgG antibody titre and BHRF-1 DNA load (rho = 0.13, p = 0.05) but not EBNA-1 DNA load (rho = 0.11, p = 0.11).

Conclusion

Two sensitive and specific real-time PCR assays using SYBR Green I dye and a single quantification standard containing two EBV DNA targets, were developed for the detection and measurement of EBV DNA load in a variety of clinical samples. These assays have application in the investigation of EBV-related illnesses in immunocompromised individuals.

Sequences of complete human cytomegalovirus genomes from infected cell cultures and clinical specimens

We have assessed two approaches to sequencing complete human cytomegalovirus (HCMV) genomes (236 kbp) in DNA extracted from infected cell cultures (strains 3157, HAN13, HAN20 and HAN38) or clinical specimens (strains JP and 3301). The first approach involved amplifying genomes from the DNA samples as overlapping PCR products, sequencing these by the Sanger method, acquiring reads from a capillary instrument and assembling these using the Staden programs. The second approach involved generating sequence data from the DNA samples by using an Illumina Genome Analyzer (IGA), processing the filtered reads by reference-independent (de novo) assembly, utilizing the resulting sequence to direct reference-dependent assembly of the same data and finishing by limited PCR sequencing. Both approaches were successful. In particular, the investigation demonstrated the utility of IGA data for efficiently sequencing genomes from clinical samples containing as little as 3 % HCMV DNA. Analysis of the genome sequences obtained showed that each of the strains grown in cell culture was a mutant. Certain of the mutations were shared among strains from independent clinical sources, thus suggesting that they may have arisen in a common ancestor during natural infection. Moreover, one of the strains (JP) sequenced directly from a clinical specimen was mutated in two genes, one of which encodes a proposed immune-evasion function, viral interleukin-10. These observations imply that HCMV mutants exist in human infections.

Impact of varicella vaccine on varicella-zoster virus dynamics

The licensure and recommendation of varicella vaccine in the mid-1990s in the United States have led to dramatic declines in varicella incidence and varicella-related deaths and hospitalizations. Varicella outbreaks remain common and occur increasingly in highly vaccinated populations. Breakthrough varicella in vaccinated individuals is characteristically mild, typically with fewer lesions that frequently do not progress to a vesicular stage. As such, the laboratory diagnosis of varicella has grown increasingly important, particularly in outbreak settings. In this review the impact of varicella vaccine on varicella-zoster virus (VZV) disease, arising complications in the effective diagnosis and monitoring of VZV transmission, and the relative strengths and limitations of currently available laboratory diagnostic techniques are all addressed. Since disease symptoms often resolve in outbreak settings before suitable test specimens can be obtained, the need to develop new diagnostic approaches that rely on alternative patient samples is also discussed.

Quantification of cytomegalovirus DNA levels in intestinal biopsies as a diagnostic tool for CMV intestinal disease

BACKGROUND

CMV intestinal disease (CMV-ID) is a serious complication in immunocompromised patients and mainly diagnosed by clinical, endoscopic and histopathologic findings, whereas qualitative CMV-PCR in tissue samples is not recommended for diagnosis due to its low positive predictive value (PPV).

OBJECTIVES

To study the interpretation and diagnostic use of CMV-quantification by PCR in intestinal tissue biopsies to recognize CMV-ID. To develop cut-off intestinal CMV-loads attributing illness to CMV.

STUDY DESIGN

CMV-genome copies in 163 biopsies from the lower intestinal tract of immunocompromised patients were determined by quantitative real-time PCR, normalized to the cell number, and retrospectively compared to histopathological analysis, clinical findings and occurrence of CMV-antigenemia. Two cut-off intestinal CMV-loads, cut-off(histo) and cut-off(clin), were defined using histopathological or clinical criteria as gold standard, respectively.

RESULTS

CMV was detected in 32.5% of biopsies with a more than six log range of CMV-concentrations (1 x 10(-4)-1.4 x 10(2)copies/cell). Notably, biopsies with histopathologically or clinically confirmed CMV-ID had a significantly higher CMV-load (p<0.001). Cut-off(histo) and cut-off(clin) were defined at the intestinal CMV-load of 0.14 and 0.01 copies/cell, respectively, and improved the PPV. However, cut-off(histo) showed a decreased sensitivity for clinically defined CMV-ID cases. Interestingly, many patients with CMV-ID showed no concomitant CMV-antigenemia, suggesting a localized intestinal CMV-replication.

CONCLUSIONS

Quantification of CMV in intestinal biopsies is a useful diagnostic tool allowing the definition of cut-off values that can predict CMV-ID more accurate than qualitative PCR results. Further prospective studies have to clarify wether these cut-offs can improve diagnostics and treatment of CMV-ID in day-to-day clinical practice.

Scaffold expulsion and genome packaging trigger stabilization of herpes simplex virus capsids

Herpes simplex virus type 1 (HSV1) capsids undergo extensive structural changes during maturation and DNA packaging. As a result, they become more stable and competent for nuclear egress. To further elucidate this stabilization process, we used biochemical and nanoindentation approaches to analyze the structural and mechanical properties of scaffold-containing (B), empty (A), and DNA-containing (C) nuclear capsids. Atomic force microscopy experiments revealed that A and C capsids were mechanically indistinguishable, indicating that the presence of DNA does not account for changes in mechanical properties during capsid maturation. Despite having the same rigidity, the scaffold-containing B capsids broke at significantly lower forces than A and C capsids. An extraction of pentons with guanidine hydrochloride (GuHCl) increased the flexibility of all capsids. Surprisingly, the breaking forces of the modified A and C capsids dropped to similar values as those of the GuHCl-treated B capsids, indicating that mechanical reinforcement occurs at the vertices. Nonetheless, it also showed that HSV1 capsids possess a remarkable structural integrity that was preserved after removal of pentons. We suggest that HSV1 capsids are stabilized after removal of the scaffold proteins, and that this stabilization is triggered by the packaging of DNA, but independent of the actual presence of DNA.