Quantitation of varicella-zoster virus DNA in whole blood, plasma, and serum by PCR and electrochemiluminescence

A Guide to Preclinical Models of Zoster-Associated Pain and Postherpetic Neuralgia

Reactivation of latent varicella-zoster virus (VZV) causes herpes zoster (HZ), which is commonly accompanied by acute pain and pruritus over the time course of a zosteriform rash. Although the rash and associated pain are self-limiting, a considerable fraction of HZ cases will subsequently develop debilitating chronic pain states termed postherpetic neuralgia (PHN). How VZV causes acute pain and the mechanisms underlying the transition to PHN are far from clear. The human-specific nature of VZV has made in vivo modeling of pain following reactivation difficult to study because no single animal can reproduce reactivated VZV disease as observed in the clinic. Investigations of VZV pathogenesis following primary infection have benefited greatly from human tissues harbored in immune-deficient mice, but modeling of acute and chronic pain requires an intact nervous system with the capability of transmitting ascending and descending sensory signals. Several groups have found that subcutaneous VZV inoculation of the rat induces prolonged and measurable changes in nociceptive behavior, indicating sensitivity that partially mimics the development of mechanical allodynia and thermal hyperalgesia seen in HZ and PHN patients. Although it is not a model of reactivation, the rat is beginning to inform how VZV infection can evoke a pain response and induce long-lasting alterations to nociception. In this review, we will summarize the rat pain models from a practical perspective and discuss avenues that have opened for testing of novel treatments for both zoster-associated pain and chronic PHN conditions, which remain in critical need of effective therapies.

Varicella zoster virus in inflammatory bowel disease patients: what every gastroenterologist should know

Primary Varicella Zoster virus (VZV) infection results in varicella (chickenpox) while its reactivation results in herpes zoster (HZ; shingles). Patients with Inflammatory Bowel Disease (IBD) are susceptible to complications of primary VZV infection and have an increased risk of HZ. Concerns of VZV and HZ infection in the IBD population has been highlighted by the emergence of JAK-inhibitors and their safety profile in this patient population such as tofacitinib for the treatment of ulcerative colitis (UC). The current pipeline of emerging therapies include novel molecules targeting multiple pathways including JAK/signal transducer and cytokine signalling pathways such as JAK/STAT. Hence VZV and HZ will be increasingly relevant for gastroenterologists treating IBD patients in light of these emerging therapies.

Manipulation of the Innate Immune Response by Varicella Zoster Virus

Varicella zoster virus (VZV) is the causative agent of chickenpox (varicella) and shingles (herpes zoster). VZV and other members of the herpesvirus family are distinguished by their ability to establish a latent infection, with the potential to reactivate and spread virus to other susceptible individuals. This lifelong relationship continually subjects VZV to the host immune system and as such VZV has evolved a plethora of strategies to evade and manipulate the immune response. This review will focus on our current understanding of the innate anti-viral control mechanisms faced by VZV. We will also discuss the diverse array of strategies employed by VZV to regulate these innate immune responses and highlight new knowledge on the interactions between VZV and human innate immune cells.

Frequency of subclinical herpes zoster in pediatric hematology-oncology patients receiving chemotherapy: A retrospective cohort analysis

Varicella-zoster virus (VZV) reactivation from the enteric nervous system can cause ileus (Ogilvie's syndrome) in adult patients. Since no pediatric cases have been described, we sought to retrospectively analyze VZV reactivation in pediatric hematology-oncology patients to determine whether VZV infection including subclinical VZV reactivation can induce gastrointestinal complications such as Ogilvie's syndrome. Thirty-five patients who received chemotherapy at our institution between September 2013 and June 2018 were included. Serum samples were collected weekly during hospitalization and every 3 months during outpatient maintenance chemotherapy. A real-time polymerase chain reaction assay was used to measure VZV DNA load in serum. The clinical features of patients with VZV infection were retrospectively analyzed. Of 1165 serum samples, 7 (0.6%) were positive for VZV DNA. VZV DNA was detected in 3 of 35 patients. In patient A, VZV DNA was detected during two episodes. The first episode involved varicella-like eruptions caused by the Oka VZV vaccine strain. The second episode involved herpes zoster (HZ) caused by the same strain. Patients B and C had a clinical course that was typical for HZ caused by wild-type VZV. No gastrointestinal symptoms were observed at the time of VZV infection in these three patients. VZV DNA was not detected in any other samples. No pediatric cases with Ogilvie's syndrome caused by VZV reactivation were demonstrated in this cohort. Additionally, no subclinical VZV reactivation was found in this cohort. Further study is needed to elucidate the precise incidence of pediatric Ogilvie's syndrome caused by VZV reactivation.

Human Herpes-8 virus copy to cell ratio: A diagnostic tool in primary effusion lymphoma

Primary effusion lymphoma (PEL) is a serious sequel to Human Herpes Virus 8 (HHV8) infection in the immunosuppressed host. Usually requiring a cytological diagnosis, body cavity effusions are often referred for investigation for possible PEL. Although absence of HHV8 effectively refutes this, the presence of HHV8 DNA, though indicative is not diagnostic. Referred effusion and plasma samples from 10 patients with HHV8-related pleural and pericardial effusions were submitted for quantitative investigations. HHV8 DNA and human DNA from unseparated effusion extracts have been quantified allowing estimation of virus-to-cell ratios in effusion fluid. These ratios varied widely between 0.003 and 700. Five fluids had in excess of 10⁶ HHV-8 DNA genome equivalents per ML (GEq/ML), ranging between 18 and 300 million GEq/ML. Four of these five effusions were from patients with cytologically proven PEL and had virus to cell (V:C) ratios between 100 and 700 to 1. The remaining high load effusion exhibited a ratio of 1.6 to 1 and came from a patient with extensive thoracic Kaposi's sarcoma. Five effusion fluids with low viral loads exhibited virus to cell ratios between 0.003 and 0.5. High effusion HHV8 load, though supportive of a diagnosis of PEL is less accurate than using virus to cell ratios.

Diagnostic Usefulness of Varicella-Zoster Virus Real-Time Polymerase Chain Reaction Analysis of DNA in Saliva and Plasma Specimens From Patients With Herpes Zoster

Background

We evaluated the diagnostic usefulness of polymerase chain reaction (PCR) analysis for detecting varicella-zoster virus (VZV) infection and reactivation of VZV, using DNA extracted from saliva and plasma specimens obtained from subjects with suspected herpes zoster and from healthy volunteers during stressful and nonstressful conditions.

Methods

There were 52 patients with a diagnosis of herpes zoster (group 1), 30 with a diagnosis of zoster-mimicking disease (group 2), and 27 healthy volunteers (group 3). Saliva and plasma samples were evaluated for VZV DNA by real-time PCR analysis.

Results

Among patients with suspected herpes zoster (ie, patients in groups 1 and 2), the sensitivity of PCR analysis of salivary DNA for detecting VZV (88%; 95% confidence interval [CI], 74%-95%) was significantly higher than that of PCR analysis of plasma DNA (28%; 95% CI, 16%-44%; P < .001), whereas the specificity of PCR analysis of salivary DNA (100%; 95% CI, 88%-100%) was similar to that of PCR analysis of plasma DNA (100%; 95% CI, 78%-100%; P > .99). VZV DNA was not detected in saliva and plasma samples from group 3 (0%; 95% CI, 0%-14%).

Conclusions

Real-time PCR analysis of salivary DNA is more sensitive than that of plasma DNA for detecting VZV among patients with suspected herpes zoster. We found no subclinical reactivation of VZV in group 3 following exposure to common stressful conditions.

Antiviral efficacy of the helicase-primase inhibitor amenamevir in murine models of severe herpesvirus infection

Existing treatments have limited efficacy against severe infection associated with herpes simplex virus (HSV) and herpes zoster virus (VZV), particularly in immunocompromized patients and those with multidermatomal infection. This issue, along with issues regarding drug resistance, support the need for improved therapeutic options. To investigate the antiviral effect of amenamevir, a VZV and HSV helicase-primase inhibitor, in severe infection conditions, mouse models of severe HSV-1 infection were developed by immunosuppression or multidermatomal infection. Mice with cyclosporin-induced immunosuppression and HSV-1 infection via inoculation of a dorsolateral area of skin were orally treated with amenamevir (10-100 mg/kg/day) for different durations (2-5 days). Immunosuppressed mice maintained high skin HSV-1 titers in the absence of treatment. Amenamevir successfully reduced HSV-1 titers at all tested doses in immunosuppressed mice, but required a longer treatment period to avoid a rebound in viral titers due to immunosuppression. To compare the efficacy of amenamevir and valacyclovir, a murine model of multidermatomal HSV-1 infection was generated by scarifying the dorsolateral area of skin in a line and inoculating broadly with HSV-1. The mice were treated with amenamevir or valacyclovir starting on Day 3, 4, or 5 post-infection for 5 days. Although both drugs similarly reduced disease scores when treatment was started on Day 3, amenamevir also reduced disease severity when treatment was initiated on Day 4, whereas valacyclovir did not. Amenamevir was not affected by the host's immune status in terms of effective oral doses and was more efficacious in treating severe cutaneous infection even when treatment initiation was delayed.

Managing varicella zoster virus contact and infection in patients on anti-rheumatic therapy

Chickenpox and shingles can be more severe and occasionally life threatening in immunosuppressed patients. As such, some groups warrant a more detailed history, serological testing and consideration of prophylaxis following contact with the virus. Active disease may also require more aggressive treatment with antivirals. Guidance for the use of varicella zoster immunoglobulin has recently been updated by Public Health England with important implications for rheumatology 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.

Varicella-zoster virus (VZV) DNA in serum of patients with VZV central nervous system infections

OBJECTIVES

Varicella-zoster virus (VZV) is a common viral agent causing central nervous system (CNS) infections, normally diagnosed by detection of VZV DNA in cerebrospinal fluid (CSF). Our aim was to investigate trends in VZV DNAemia in VZV CNS infections, which could potentially contribute to diagnosis and secondly, correlate the amount of VZV DNA in serum to severity of disease.

METHODS

Seventy-two patients with VZV CNS infections diagnosed by detection of VZV DNA in CSF and concomitant neurological symptoms were included. The amount of VZV DNA was measured by real-time PCR in paired serum and CSF samples and compared to a control group of herpes zoster (n = 36).

RESULTS

An increased amount of VZV DNA was detected in serum in patients with encephalitis compared to patients with meningitis or Ramsay-Hunt syndrome, respectively (p = 0.003 and p = 0.024). A greater proportion of patients with VZV CNS infections and detectable VZV DNA in serum had ongoing rash compared to those without detectable VZV DNA in serum (p ≤ 0.001). The viral load in serum of patients with neurological symptoms was lower compared to in patients with herpes zoster without neurological symptoms (p ≤ 0.001) and only 32/72 of the patients with VZV CNS disease had VZV DNA detected in serum.

CONCLUSION

Increased amount of VZV DNA in serum of patients with VZV CNS infections seems associated with encephalitis and ongoing rash. Additionally, viral DNA analysis by PCR in serum may be a helpful diagnostic tool although viral DNA analysis by PCR in CSF is the method of choice for diagnosis.

Fatal Varicella Myocarditis in a Child with Down Syndrome-A Case Report

A 12-year-old male child with Down syndrome, who had recovered from congenital heart disease, succumbed to severe varicella myocarditis. His clinical presentation at admission mimicked acute coronary syndrome. Analysis of this case throws insight into several aspects of varicella myocarditis.

Varicella vaccination in pediatric oncology patients without interruption of chemotherapy

BACKGROUND

Morbidity and mortality from primary varicella-zoster virus (VZV) infection is increased in immunocompromised children. Vaccination of VZV-seronegative cancer patients with live-attenuated varicella vaccine is safe when chemotherapy is interrupted. However, VZV vaccination without interruption of chemotherapy would be preferable.

OBJECTIVE

To vaccinate VZV-seronegative pediatric oncology patients with live-attenuated VZV vaccine without interrupting their chemotherapy.

STUDY-DESIGN

We performed a single-center prospective cohort study.

RESULTS

Thirty-one patients with either a hematological malignancy (n=24) or a solid tumor (n=7) were vaccinated early during their course of chemotherapy. VZV IgG seroconversion occurred in 14 of the 31 patients (45%) after one vaccination. Only 20 patients were revaccinated after 3 months. These were patients who did not seroconvert (5 patients) and patients who serocoverted (15 patients) to induce or sustain seropositivity. Of these 20 patients the final seroconversion rate was 70%. Seven out of the 31 patients (23%) developed a mild rash of which 5 were treated with antivirals and recovered completely without interrupting chemotherapy, and 2 recovered untreated. Of these 31 immunized patients 26 were available for cellular testing. After one vaccination 20 of 26 patients (77%) tested positive for VZV-specific CD4(+) T cells, of which 7 patients had remained VZV-seronegative. After the second vaccination 11 of 11 patients showed VZV-specific CD4(+) T cells to sustain positivity, although 4 remained VZV-seronegative.

CONCLUSIONS

This study indicates that live-attenuated VZV vaccine can be safely administered to closely monitored pediatric oncology patients without interruption of chemotherapy and adaptive immunity was induced despite incomplete seroconversion.

Varicella-zoster virus and virus DNA in the blood and oropharynx of people with latent or active varicella-zoster virus infections

Varicella-zoster virus (VZV) can be detected in the blood from approximately 5 days before to 4 days after varicella. VZV DNA, primarily in T-lymphocytes, is detected as early as 8-10 days prior to rash and can persist for a week. The duration and magnitude of VZV DNAemia correlates with immune status and the efficacy of antiviral therapy. VZV DNA is also readily detected in the oropharynx just prior to rash and for 1-2 weeks thereafter. Detection of VZV DNA in blood and saliva has been useful for diagnosis and prognosis in atypical cases of varicella. Herpes zoster (HZ) is also characterized by VZV DNAemia at onset and for many weeks thereafter, and VZV DNA is present in the oropharynx shortly after HZ onset. Detection of VZV DNA in blood and saliva facilitates the diagnosis of zoster sine herpete and other atypical manifestations of VZV reactivation, such as neurologic syndromes when cerebrospinal fluid is not available, Bell's palsy, and atypical pain syndromes. VZV DNA is sometimes present in the blood and saliva of asymptomatic individuals. In total these observations extend understanding of the pathophysiology and epidemiology of VZV, and increasingly contribute to the clinical management of VZV infections.

Analytical characterization of an assay designed to detect and identify diverse agents of disseminated viral infection

BACKGROUND

Diverse viruses often reactivate in or infect cancer patients, patients with immunocompromising infections or genetic conditions, and transplant recipients undergoing immunosuppressive therapy. These infections can disseminate, leading to death, transplant rejection, and other severe outcomes.

OBJECTIVES

To develop and characterize an assay capable of inclusive and accurate identification of diverse potentially disseminating viruses directly from plasma specimens.

STUDY DESIGN

We developed a PCR/electrospray ionization mass spectrometry (PCR/ESI-MS) assay designed to simultaneously detect and identify adenovirus, enterovirus, polyomaviruses JC and BK, parvovirus B19, HSV-1, HSV-2, VZV, EBV, CMV, and herpesviruses 6-8 in plasma specimens. The assay performance was characterized analytically, and the results from clinical plasma samples were compared to the results obtained from single-analyte real time PCR tests currently used in clinical practice.

RESULTS

The assay demonstrated sensitivity and specificity to diverse strains of the targeted viral families and robustness to interfering substances and potentially cross reacting organisms. The assay yielded 94% sensitivity when testing clinical plasma samples previously identified as positive using standard-of-care real-time PCR tests for a single target virus (available samples included positive samples for 11 viruses targeted by the assay).

CONCLUSIONS

The assay functioned as designed, providing simultaneous broad-spectrum detection and identification of diverse agents of disseminated viral infection. Among 156 clinical samples tested, 37 detections were made in addition to the detections matching the initial clinical positive results.

A prospective study of the causes of febrile illness requiring hospitalization in children in Cambodia

Background

Febrile illnesses are pre-eminent contributors to morbidity and mortality among children in South-East Asia but the causes are poorly understood. We determined the causes of fever in children hospitalised in Siem Reap province, Cambodia.

Methods and Findings

A one-year prospective study of febrile children admitted to Angkor Hospital for Children, Siem Reap. Demographic, clinical, laboratory and outcome data were comprehensively analysed. Between October 12^th 2009 and October 12^th 2010 there were 1225 episodes of febrile illness in 1180 children. Median (IQR) age was 2.0 (0.8–6.4) years, with 850 (69%) episodes in children <5 years. Common microbiological diagnoses were dengue virus (16.2%), scrub typhus (7.8%), and Japanese encephalitis virus (5.8%). 76 (6.3%) episodes had culture-proven bloodstream infection, including Salmonella enterica serovar Typhi (22 isolates, 1.8%), Streptococcus pneumoniae (13, 1.1%), Escherichia coli (8, 0.7%), Haemophilus influenzae (7, 0.6%), Staphylococcus aureus (6, 0.5%) and Burkholderia pseudomallei (6, 0.5%). There were 69 deaths (5.6%), including those due to clinically diagnosed pneumonia (19), dengue virus (5), and melioidosis (4). 10 of 69 (14.5%) deaths were associated with culture-proven bloodstream infection in logistic regression analyses (odds ratio for mortality 3.4, 95% CI 1.6–6.9). Antimicrobial resistance was prevalent, particularly in S. enterica Typhi, (where 90% of isolates were resistant to ciprofloxacin, and 86% were multi-drug resistant). Comorbid undernutrition was present in 44% of episodes and a major risk factor for acute mortality (OR 2.1, 95% CI 1.1–4.2), as were HIV infection and cardiac disease.

Conclusion

We identified a microbiological cause of fever in almost 50% of episodes in this large study of community-acquired febrile illness in hospitalized children in Cambodia. The range of pathogens, antimicrobial susceptibility, and co-morbidities associated with mortality described will be of use in the development of rational guidelines for infectious disease treatment and control in Cambodia and South-East Asia.

Sampling of herpes zoster skin lesion types and the impact on viral DNA detection

This was a multicenter, non-therapeutic study to determine the optimal type of lesion sample for quantitative PCR detection of varicella zoster virus (VZV) DNA in herpes zoster patients. Up to three crusts, three crust swabs, three vesicle swabs, and three papule swabs were collected from 41 adults with clinically diagnosed herpes zoster. 83% of subjects had at least one valid crust swab (detectable VZV or β-actin DNA), 78% had at least one valid crust, 78% had at least one valid vesicle swab, and 32% had at least one valid papule swab. Of valid samples, 97% of crusts, 94% of vesicle swabs, 90% of crust swabs, and 84% of papule swabs were VZV-DNA-positive (≥10 DNA copies/sample). 37 (90%) subjects had at least one VZV DNA-positive sample. VZV DNA copy numbers were highest for vesicle swabs and crusts. The probability of a false-negative result was 5% for crusts, 6% for vesicle swabs, 14% for papule swabs, and 24% for crust swabs. Overall, vesicle swabs and crusts were the most specific and sensitive samples for detecting VZV.

The spectrum of central nervous system infections in an adult referral hospital in Hanoi, Vietnam

Objectives

To determine prospectively the causative pathogens of central nervous system (CNS) infections in patients admitted to a tertiary referral hospital in Hanoi, Vietnam.

Methods

From May 2007 to December 2008, cerebrospinal fluid (CSF) samples from 352 adults with suspected meningitis or encephalitis underwent routine testing, staining (Gram, Ziehl-Nielsen, India ink), bacterial culture and polymerase chain reaction targeting Neisseria meningitidis, Streptococcus pneumoniae, S. suis, Haemophilus influenzae type b, Herpes simplex virus (HSV), Varicella Zoster virus (VZV), enterovirus, and 16S ribosomal RNA. Blood cultures and clinically indicated radiology were also performed. Patients were classified as having confirmed or suspected bacterial (BM), tuberculous (TBM), cryptococcal (CRM), eosinophilic (EOM) meningitis, aseptic encephalitis/meningitis (AEM), neurocysticercosis and others.

Results

352 (male: 66%) patients were recruited: median age 34 years (range 13–85). 95/352 (27.3%) diagnoses were laboratory confirmed and one by cranial radiology: BM (n = 62), TBM (n = 9), AEM (n = 19), CRM (n = 5), and neurocysticercosis (n = 1, cranial radiology). S. suis predominated as the cause of BM [48/62 (77.4%)]; Listeria monocytogenese (n = 1), S. pasteurianus (n = 1) and N. meningitidis (n = 2) were infrequent. AEM viruses were: HSV (n = 12), VZV (n = 5) and enterovirus (n = 2). 5 patients had EOM. Of 262/352 (74.4%) patients with full clinical data, 209 (79.8%) were hospital referrals and 186 (71%) had been on antimicrobials. 21 (8%) patients died: TBM (15.2%), AEM (10%), and BM (2.8%).

Conclusions

Most infections lacked microbiological confirmation. S. suis was the most common cause of BM in this setting. Improved diagnostics are needed for meningoencephalitic syndromes to inform treatment and prevention strategies.

Review: The neurobiology of varicella zoster virus infection

Varicella zoster virus (VZV) is a neurotropic herpesvirus that infects nearly all humans. Primary infection usually causes chickenpox (varicella), after which virus becomes latent in cranial nerve ganglia, dorsal root ganglia and autonomic ganglia along the entire neuraxis. Although VZV cannot be isolated from human ganglia, nucleic acid hybridization and, later, polymerase chain reaction proved that VZV is latent in ganglia. Declining VZV-specific host immunity decades after primary infection allows virus to reactivate spontaneously, resulting in shingles (zoster) characterized by pain and rash restricted to one to three dermatomes. Multiple other serious neurological and ocular disorders also result from VZV reactivation. This review summarizes the current state of knowledge of the clinical and pathological complications of neurological and ocular disease produced by VZV reactivation, molecular aspects of VZV latency, VZV virology and VZV-specific immunity, the role of apoptosis in VZV-induced cell death and the development of an animal model provided by simian varicella virus infection of monkeys.

Compartmentalization of acyclovir-resistant varicella zoster virus: implications for sampling in molecular diagnostics

BACKGROUND

Acyclovir resistance of varicella zoster virus (VZV) may arise in stem cell transplant (SCT) recipients with VZV disease and is usually a result of mutations in VZV thymidine kinase (TK), which is the target protein of acyclovir. Early detection of such mutations is necessary to enable timely therapy adaptation, for example, to foscarnet. We aimed to investigate whether TK mutations arise over time, and what sample types might be the most useful for this method.

METHODS

Spatially and temporally distinct samples from 3 SCT recipients with VZV disease unresponsive to acyclovir treatment were retrospectively investigated for the presence of TK mutations by polymerase chain reaction and sequence analysis.

RESULTS

In all 3 patients, a mutation in the VZV TK coding region was found resulting in an amino acid substitution. TK mutations were not only temporally but also spatially compartmentalized. In particular, plasma samples frequently showed wild-type TK sequences, whereas cerebrospinal fluid or skin vesicle fluid acquired on the same day contained mutant sequences.

CONCLUSIONS

This study shows the importance of careful sampling for molecular diagnostics of acyclovir resistance in VZV disease. All affected body sites should be sampled and plasma samples may not be representative for the viral mutation status.

Persistence of varicella-zoster virus viraemia in patients with herpes zoster

BACKGROUND

Herpes zoster is caused by the reactivation of varicella-zoster virus from sensory neurons. The commonest complication following zoster is chronic pain termed post herpetic neuralgia.

OBJECTIVES

To investigate the dynamics of VZV viraemia and viral load following the resolution of zoster and its relationship to PHN development.

STUDY DESIGN

Blood samples were collected at baseline, 1 month, 3 months and 6 month from a prospective study of 63 patients with active zoster. Quantification of VZV DNA in whole blood was performed using a real-time PCR assay.

RESULTS

During acute zoster, all patients had detectable VZV DNA in their blood. VZV DNA remained detectable in the blood of 91% of patients at 6 months although levels declined significantly (p<0.0001). A history of prodromal symptoms (p=0.005) and severity of pain at baseline (p=0.038) as well as taking antivirals (p=0.046) and being immunocompromised (p=0.043) were associated, with longer time to recovery from PHN. Viral DNA loads were consistently higher in patients with risk factors for PHN and higher viral DNA loads over time were associated with longer time to recovery (p=0.058 overall and 0.038 in immunocompetent).

CONCLUSIONS

Based on these observations we hypothesise that VZV replication persists following acute shingles and that higher viral DNA loads contribute to the risk factors for PHN.

Use of preconditioned human phagocytes for extracorporeal adsorption of viruses

Conventional treatment of severe viral disease is limited by the narrow choice as well as the often-significant side effects or lack of clear efficacy of antiviral chemotherapy. At the same time, however, it is known that a reduction in viral load leads to significant clinical improvement in a number of important viral diseases. In this paper we discuss the possibility of using preconditioned human phagocytes in an extracorporeal biohybrid system for adsorption of viral pathogens. We present data from in vitro experiments testing adsorption of an enterovirus and of hepatitis B virus (HBV) by a preconditioned human promyelocytic cell line. While no clearance of HBV could be detected, the results revealed a near elimination of enterovirus with the cell line displaying robust viability. Enterovirus titers of 1000 (reciprocal) were reduced to a mean titer of 10(0.6) CCID(50) with no virus detectable after adsorption in two out of five samples. Titers of 10000 (reciprocal) were in turn reduced to a mean of 10(1.4) CCID(50). The kinetics of the process was remarkable with this near elimination of the pathogen occurring within only 15min. Extracorporeal viral adsorption by a cellular biohybrid system appears feasible. Pairing target pathogens with suitable cell lines may offer a versatile antiviral technology.

Occult varicella

BACKGROUND

Localized varicella has been associated with UV-exposure and skin trauma. Varicella restricted to a pre-existent dermatitis is exceptional.

OBJECTIVES

The clinical features, cytohistologic and immunohistochemical results, as well as serologic data of 6 patients with a sudden eruption of vesicular and eroded lesions restricted to a pre-existent dermatitis are presented.

RESULTS

All patients (mean age: 8,3 years, range: 3-22) showed crops of a few to numerous vesicular lesions clustered on the restricted sites of posttraumatic wound, perianal streptococcal dermatitis, dermatomycosis, allergic contact dermatitis, lichen sclerosus, and atopic foot dermatitis. All the Tzanck smears and 1 biopsy revealed multinucleated giant cells, consistent with herpes simplex virus (HSV) or varicella zoster virus (VZV) infection. Immunohistochemistry using specific anti-VZV antibodies (IE63 and gE) was positive on all the smears and the biopsy, whereas HSV-I and HSV-II immunolabeling was negative. VZV specific IgM+, IgG- EIA-based serology, and positive VZV-specific IgM complement fixation test suggested primary VZV infection. None had received varicella vaccine. None of the patients presented a history of varicella nor experienced breakthrough varicella. It was decided not to administer antiviral treatment, as the varicella lesions remained localized without any further skin extension and systemic signs. About 2 months later, EIA-serology revealed positive VZV-IgG and negative IgM levels in 5/5 patients.

CONCLUSION

Some patients have varicella infection that remains hidden in a pre-existent infectious and/or inflammatory dermatitis without ever presenting full-blown chickenpox. The sudden occurrence of vesicular and/or ulcerated lesions on a pre-existent dermatitis should prompt searching for a viral infection.

Simian varicella virus infection of rhesus macaques recapitulates essential features of varicella zoster virus infection in humans

Simian varicella virus (SVV), the etiologic agent of naturally occurring varicella in primates, is genetically and antigenically closely related to human varicella zoster virus (VZV). Early attempts to develop a model of VZV pathogenesis and latency in nonhuman primates (NHP) resulted in persistent infection. More recent models successfully produced latency; however, only a minority of monkeys became viremic and seroconverted. Thus, previous NHP models were not ideally suited to analyze the immune response to SVV during acute infection and the transition to latency. Here, we show for the first time that intrabronchial inoculation of rhesus macaques with SVV closely mimics naturally occurring varicella (chickenpox) in humans. Infected monkeys developed varicella and viremia that resolved 21 days after infection. Months later, viral DNA was detected only in ganglia and not in non-ganglionic tissues. Like VZV latency in human ganglia, transcripts corresponding to SVV ORFs 21, 62, 63 and 66, but not ORF 40, were detected by RT-PCR. In addition, as described for VZV, SVV ORF 63 protein was detected in the cytoplasm of neurons in latently infected monkey ganglia by immunohistochemistry. We also present the first in depth analysis of the immune response to SVV. Infected animals produced a strong humoral and cell-mediated immune response to SVV, as assessed by immunohistology, serology and flow cytometry. Intrabronchial inoculation of rhesus macaques with SVV provides a novel model to analyze viral and immunological mechanisms of VZV latency and reactivation.

Viral load, clinical disease severity and cellular immune responses in primary varicella zoster virus infection in Sri Lanka

BACKGROUND

In Sri Lanka, varicella zoster virus (VZV) is typically acquired during adulthood with significant associated disease morbidity and mortality. T cells are believed to be important in the control of VZV replication and in the prevention of reactivation. The relationship between viral load, disease severity and cellular immune responses in primary VZV infection has not been well studied.

METHODOLOGY

We used IFNgamma ELISpot assays and MHC class II tetramers based on VZV gE and IE63 epitopes, together with quantitative real time PCR assays to compare the frequency and phenotype of specific T cells with virological and clinical outcomes in 34 adult Sri Lankan individuals with primary VZV infection.

PRINCIPAL FINDINGS

Viral loads were found to be significantly higher in patients with moderate to severe infection compared to those with mild infection (p<0.001) and were significantly higher in those over 25 years of age (P<0.01). A significant inverse correlation was seen between the viral loads and the ex vivo IFNgamma ELISpot responses of patients (P<0.001, r = -0.85). VZV-specific CD4+ T cells expressed markers of intermediate differentiation and activation.

CONCLUSIONS

Overall, these data show that increased clinical severity in Sri Lankan adults with primary VZV infection associates with higher viral load and reduced viral specific T cell responses.

DNA sequence analysis of varicella-zoster virus gene 62 from subclinical infections in healthy children immunized with the Oka varicella vaccine

A live attenuated varicella vaccine, the Oka vaccine strain (vOka), is routinely administered to children in Japan and other countries, including the United States. vOka consists of a mixture of genotypically distinct variants, but little is known about the growth potential of each variants in vivo. We isolated varicella-zoster virus (VZV) DNA sequences from the peripheral blood mononuclear cells (PBMCs) of asymptomatic healthy children immunized with the Oka varicella vaccine. VZV gene 62 DNA fragments were detected in 5 of 166 (3.0%) PBMC samples by nested PCR within 5 weeks of the vaccination. Sequence analysis of VZV DNA from these five PBMC samples indicated that multiple viral clones in the vaccine could infect vaccinees and replicate in vivo. We also provide evidence that a nonsynonymous substitution at position 105356 may affect viral replication in vivo.

Varicella zoster virus infection: clinical features, molecular pathogenesis of disease, and latency

Varicella zoster virus (VZV) is an exclusively human neurotropic alphaherpesvirus. Primary infection causes varicella (chickenpox), after which virus becomes latent in cranial nerve ganglia, dorsal root ganglia, and autonomic ganglia along the entire neuraxis. Years later, in association with a decline in cell-mediated immunity in elderly and immunocompromised individuals, VZV reactivates and causes a wide range of neurologic disease. This article discusses the clinical manifestations, treatment, and prevention of VZV infection and reactivation; pathogenesis of VZV infection; and current research focusing on VZV latency, reactivation, and animal models.

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.

Effect of viral load on the outcome of herpes zoster

Varicella-zoster virus (VZV) is a member of the Herpesviridae family, primary infection with which causes varicella, more commonly known as chicken pox. Characteristic of members of the alphaherpesvirus subfamily, VZV is neurotropic and establishes latency in sensory neurons. Reactivation of VZV causes herpes zoster, also known as shingles. The most frequent complication following zoster is chronic and often debilitating pain called postherpetic neuralgia (PHN), which can last for months after the disappearance of a rash. During episodes of acute zoster, VZV viremia occurs in some, but not all, patients; however, the effect of the viral load on the disease outcome is not known. Here we describe the development of a highly specific, sensitive, and reproducible real-time PCR assay to investigate the factors that may contribute to the presence and levels of baseline viremia in patients with zoster and to determine the relationship between viremia and the development and persistence of PHN. VZV DNA was detected in the peripheral blood mononuclear cells (PBMCs) of 78% of patients with acute zoster and in 9% of healthy asymptomatic blood donors. The presence of VZV in the PBMCs of patients with acute zoster was independently associated with age and being on antivirals but not with gender, immune status, extent of rash, the age of the rash at the time of blood sampling, having a history of prodromal pain, or the extent of acute pain. Prodromal pain was significantly associated with higher baseline viral loads. Viral load levels were not associated with the development or persistence of PHN at 6, 12, or 26 weeks.

Downregulation of class I major histocompatibility complex surface expression by varicella-zoster virus involves open reading frame 66 protein kinase-dependent and -independent mechanisms

We show here that the varicella-zoster virus (VZV) open reading frame 66 (ORF66) protein kinase is one mechanism employed to reduce class I major histocompatibility complex (MHC-I) surface expression in VZV-infected cells. Cells expressing enhanced green fluorescent protein-tagged functional and inactivated ORF66 (GFP-66 and GFP-66kd) from replication-defective adenovirus vectors revealed that ORF66 reduced MHC-I surface levels in a manner dependent on kinase activity. Cells infected with recombinant VZV expressing GFP-66 exhibited a significantly greater reduction in MHC-I surface expression than that observed in cells infected with VZV disrupted in GFP-66 expression. MHC-I maturation was delayed in its transport from the endoplasmic reticulum through the Golgi in both adenovirus-transduced cells expressing only GFP-66 and in VZV-infected cells expressing high levels of GFP-66, and this was predominantly kinase dependent. MHC-I levels were reduced in VZV-infected cells, and analyses of intracellular MHC-I revealed accumulation of folded MHC-I in the Golgi region, irrespective of ORF66 expression. Thus, the ORF66 kinase is important for VZV-mediated MHC-I downregulation, but additional mechanisms also may be involved. Analyses of the VZV ORF9a protein, the ortholog of the bovine herpesvirus 1 transporter associated with antigen processing inhibitor UL49.5 revealed no effects on MHC-I. These results establish a new role for viral protein kinases in immune evasion and suggest that VZV utilizes unique mechanisms to inhibit antigen presentation.

Herpes simplex and varicella zoster viruses: forgotten but not gone

Herpesvirus infections are common complications of organ transplantation. The most frequent herpesvirus infections are caused by cytomegalovirus (CMV), herpes simplex (HSV) and varicella zoster (VZV). Despite expansion of the therapeutic armamentarium, HSV and VZV continue to cause morbidity and occasional mortality in transplant recipients. Here we review the incidence and risk factors for HSV and VZV disease, their clinical presentation, effects of newer immunosuppressive regimens and prophylaxis for HSV and VZV in solid organ transplant recipients.

Electrochemiluminescent hybridization chip with electric field aided mismatch discrimination

This paper describes a heterogeneous DNA-hybridization assay based on electrochemiluminescence (ECL) detection on gold electrodes. Short, 15-mer oligonucleotides were conjugated with a synthesized electrochemiluminescent label, bis(2,2'-bipyridine)-5-isothiocyanato-1,10-phenanthroline ruthenium(II) at the amino-modified 5'-end. Gold electrodes were derivatized with 15-mer oligonucleotide probes via 1-(3-(dimethylamino)propyl)-3-ethylcarbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) cross-linking reaction and hybridized with Ru-labeled strands. Two types of self-assembled-monolayers have been utilized for the immobilization reaction, 3-mercaptopropanoic acid (3-MHA) and 16-mercaptohexadecanoic acid (16-MHA). Longer thiols were more stable at high electrode potentials needed for the ECL generation. The system was sensitive down to 1 fmol of labeled complementary strand, detected in 30 microL of buffer. Mismatch discrimination was achieved both passively by washing and actively by application of negative electrode potential on electrodes prior to detection, but active denaturing lead to better results. Two base-pair mismatches were discriminated at room temperature.

Clinical relevance of quantitative varicella-zoster virus (VZV) DNA detection in plasma after stem cell transplantation

Detection of Varicella-Zoster virus (VZV) DNA in plasma can facilitate the early recognition of complicated VZV-infection in immunocompromised hosts. The correlation of VZV-DNA in plasma with clinical presentations of VZV-infection and subsequent aciclovir treatment in allogeneic stem cell transplant (allo-SCT) recipients was studied. In 81 consecutive VZV-IgG positive allo-SCT recipients, VZV-DNA was measured at regular time points (1, 2 and 4 months) following allo-SCT and patient records were screened for VZV-related symptoms and aciclovir treatment. Subsequently, possible VZV-cases were studied in detail for the course of VZV-DNA and treatment effects. During the initial screening, VZV-DNA was detectable in seven patients. The survey of VZV-related symptoms revealed five additional possible VZV-cases. In cases where suitable plasma samples were available (10 out of 12), VZV-DNA was present almost simultaneously with the first clinical manifestations. No evidence of a preceding phase detectable by VZV-DNA only could be observed. Treatment with aciclovir was associated with a prompt reduction of VZV-DNA load. Detection of VZV-DNA in plasma in allo-SCT recipients accurately reflected the clinical presentation of VZV-infection and treatment with aciclovir. VZV-DNA detection in plasma of allo-SCT recipients appears clinically relevant as this may support early recognition and therapeutic management of VZV-infections following allo-SCT.

Persistent detection of varicella-zoster virus DNA in a previously healthy child after severe chickenpox

In immunocompetent children with primary varicella-zoster virus (VZV) infection, peak viral loads are detected in peripheral blood near the onset of the vesicular rash. VZV DNA concentrations normally diminish and become undetectable within 3 weeks after the appearance of the exanthem. Here, we present a previously healthy, human immunodeficiency virus-negative, 4-year-old boy admitted with severe varicella. High viral loads (>340,000 copies/ml) were found in his blood, and the viral loads remained high for at least 1.5 years. Clinical recovery preceded complete clearance of the virus. General and VZV-specific immune reactivity were intact. NK cells and CD8(+) T cells were activated during acute infection, and VZV-specific CD4(+) T cells were detected at high frequencies. VZV DNA was initially detected in B cells, NK cells, and both CD4(+) and CD8(+) T cells. In contrast, during the persistent phase of VZV DNA detection, the viral DNA was primarily located in CD8(+) T cells. For the first time, we describe the persistent detection of VZV DNA in a previously healthy child.

Reduced PCR sensitivity due to impaired DNA recovery with the MagNA Pure LC total nucleic acid isolation kit

The increasing demand for molecular diagnostics in clinical microbiology laboratories necessitates automated sample processing. In the present study, we evaluated the performance of the MagNA Pure LC total nucleic acid isolation kit (M extraction) in comparison with the manual method (Si extraction) according to Boom et al. (R. Boom, C. J. A. Sol, M. M. M. Salimans, C. L. Jansen, P. M. Wertheim-van Dillen, and J. van der Noordaa, J. Clin. Microbiol. 28:495-503, 1990) for the detection of viral DNA by competitive quantitative PCR. Reconstruction experiments with HindIII-digested phage lambda DNA and HaeIII-digested phiX174 DNA showed that the recovery of DNA from phosphate-buffered saline, cerebrospinal fluid, EDTA-anticoagulated plasma, and EDTA-anticoagulated whole blood by M extraction is, on average, 6.6-fold lower compared to Si extraction. PCR signals of spiked PCR control DNAs for Epstein-Barr virus and varicella-zoster virus were also between 1.9- and 14.2-fold lower after M extraction compared to Si extraction, also suggesting impaired DNA recovery. M extraction of spiked cytomegalovirus strain AD 169 in whole blood showed a 5- to 10-fold reduction in PCR sensitivity compared to Si extraction. This reduction of PCR sensitivity was also observed when clinical whole blood samples were processed by M extraction. Before implementing M extraction, the clinical consequences of the reduced recovery should first be considered, especially when maximal sensitivity is required.

Retrospective analysis of varicella zoster virus (VZV) copy DNA numbers in plasma of immunocompetent patients with herpes zoster, of immunocompromised patients with disseminated VZV disease, and of asymptomatic solid organ transplant recipients

BACKGROUND

Varicella zoster virus (VZV) causes significant morbidity and mortality in immunocompromised patients. Subclinical reactivation has been described in solid organ recipients and has been associated with graft versus host disease in bone marrow transplantation. Newer studies assessing the prevalence and impact of subclinical VZV reactivation in solid organ transplant (SOT) recipients are lacking.

METHODS AND RESULTS

In a first step we developed a highly sensitive quantitative polymerase chain reaction (qPCR) assay for VZV DNA with a detection limit of < or = 20 copies/mL. Using this assay, we retrospectively analyzed plasma samples of different patient groups for VZV DNA. VZV DNA was found in 10/10 plasma samples of immunocompetent patients with herpes zoster (VZV copy numbers/mL: mean+/-SEM 1710+/-1018), in 1/1 sample of a human immunodeficiency virus-infected patient with primary VZV disease (15,192 copies/mL) and in 4/4 plasma samples of immunocompromised patients with visceral VZV disease (mean of first value 214,214+/-178,572). All 108 plasma samples of asymptomatic SOT recipients off any antiviral therapy, randomly sampled over 1 year, were negative for VZV DNA.

CONCLUSION

Our qPCR assay proved to be highly sensitive (100%) in symptomatic VZV disease. We did not detect subclinical reactivation in asymptomatic SOT recipients during the first post-transplant year. Thus, subclinical VZV reactivation is either a rare event or does not exist. These data need to be confirmed in larger prospective trials.

Detection of genetically modified organisms by electrochemiluminescence PCR method

With the development of biotechnology, more and more genetically modified organisms (GMOs) have entered commercial market. Because of the safety concerns, detection and characterization of GMOs have attracted much attention recently. In this study, electrochemiluminescence polymerase chain reaction (ECL-PCR) combined with hybridization technique was applied to detect the GMOs in genetically modified (GM) soybeans and papayas for the first time. Whether the soybeans and the papayas contain GM components was discriminated by detecting the Cauliflower mosaic virus 35S (CaMV35S) promoter. The experiment results show that the detection limit for CaMV35S promoter is 100 fmol, and the GM components can be clearly identified in GM soybeans and papayas. The technique may provide a new means in GMOs detection due to its simplicity and high efficiency.