Visceral varicella zoster virus (VZV) after allogeneic hematopoietic stem cell transplant (HSCT) in pediatric patients with chronic graft-versus-host disease (cGVHD)

Intractable abdominal pain as the sole symptom of Varicella Zoster reactivation after allogeneic stem cell transplantation: brief case report and review of the literature

After primary infection, Varicella Zoster (VZV) persists in sensory dorsal root ganglia and may be reactivated in periods of diminished T-cell immunity. Varicella Zoster reactivation post allogenic stem cell transplantation (HSCT) can be challenging to diagnose as it does not always present with characteristic skin lesions. We describe a pediatric patient who presented with isolated severe abdominal pain with no other symptoms. Cutaneous lesions appeared only 10 days later resulting in delayed diagnosis and treatment. He was successfully treated with intravenous acyclovir and recovered after a prolonged hospital stay with post-herpetic neuralgia. Abdominal pain in children post HSCT has a broad differential and VZV reactivation should be considered even in absence of cutaneous lesions. Early diagnosis and treatment are essential to reduce VZV-related morbidity and mortality. In this article we present a case report and review clinical presentation and outcome of similar cases in the literature.

Pediatric Acute Liver Failure: A Clinicopathological Perspective

Pediatric acute liver failure (PALF) is a life-threatening disorder characterized by acute hepatocellular injury occurring in children without recognized underlying liver disease. The clinicopathologic evaluation of PALF requires a different approach from that in adults. The diagnostic considerations differ depending on the age, personal and family history, geographical region, and clinical presentation. Distinct entities such as gestational alloimmune liver disease, herpes simplex virus infection, and metabolic disorders should be considered in neonates with acute liver failure, while acetaminophen toxicity and autoimmune hepatitis are more frequently seen in older children and adolescents. An identified cause for PALF despite a negative complete evaluation (indeterminate) is lacking in 30 to 50% of cases. Although not routinely performed in the setting of PALF, liver biopsy may be helpful in assessing the etiology, potential mechanisms of injury, determining the appropriateness of liver transplantation, and prognostication of the patients. In this article, we review the clinicopathologic characteristics of PALF with an emphasis on general approach of pathologic evaluation and histopathologic characteristic of selected entities.

Management of Chronic Graft-vs.-Host Disease in Children and Adolescents With ALL: Present Status and Model for a Personalised Management Plan

Herein we review current practice regarding the management of chronic graft-vs.-host disease (cGvHD) in paediatric patients after allogeneic haematopoietic stem cell transplantation (HSCT) for acute lymphoblastic leukaemia (ALL). Topics covered include: (i) the epidemiology of cGvHD; (ii) an overview of advances in our understanding cGvHD pathogenesis; (iii) current knowledge regarding risk factors for cGvHD and prevention strategies complemented by biomarkers; (iii) the paediatric aspects of the 2014 National Institutes for Health-defined diagnosis and grading of cGvHD; and (iv) current options for cGvHD treatment. We cover topical therapy and newly approved tyrosine kinase inhibitors, emphasising the use of immunomodulatory approaches in the context of the delicate counterbalance between immunosuppression and immune reconstitution as well as risks of relapse and infectious complications. We examine real-world approaches of response assessment and tapering schedules of treatment. Furthermore, we report on the optimal timepoints for therapeutic interventions and changes in relation to immune reconstitution and risk of relapse/infection. Additionally, we review the different options for anti-infectious prophylaxis. Finally, we put forth a theory of a holistic view of paediatric cGvHD and its associated manifestations and propose a checklist for individualised risk evaluation with aggregated considerations including site-specific cGvHD evaluation with attention to each individual's GvHD history, previous medical history, comorbidities, and personal tolerance and psychosocial circumstances. To complement this checklist, we present a treatment algorithm using representative patients to inform the personalised management plans for patients with cGvHD after HSCT for ALL who are at high risk of relapse.

Hinge Region in DNA Packaging Terminase pUL15 of Herpes Simplex Virus: A Potential Allosteric Target for Antiviral Drugs

Approximately 80% of adults are infected with a member of the herpesviridae family. Herpesviruses establish life-long latent infections within neurons, which may reactivate into lytic infections due to stress or immune suppression. There are nine human herpesviruses (HHV) posing health concerns from benign conditions to life threatening encephalitis, including cancers associated with viral infections. The current treatment options for most HHV conditions mainly include several nucleoside and nucleotide analogs targeting viral DNA polymerase. Although these drugs help manage infections, their common mechanism of action may lead to the development of drug resistance, which is particularly devastating in immunocompromised patients. Therefore, new classes of drugs directed against novel targets in HHVs are necessary to alleviate this issue. We analyzed the conservation rates of all proteins in herpes simplex virus 1 (HHV-1), a representative of the HHV family and one of the most common viruses infecting the human population. Furthermore, we generated a full-length structure model of the most conserved HHV-1 protein, the DNA packaging terminase pUL15. A series of computational analyses were performed on the model to identify ATP and DNA binding sites and characterize the dynamics of the protein. Our study indicates that proteins involved in HHV-1 DNA packaging and cleavage are amongst the most conserved gene products of HHVs. Since the packaging protein pUL15 is the most conserved among all HHV-1 gene products, the virus will have a lower chance of developing resistance to small molecules targeting pUL15. A subsequent analysis of the structure of pUL15 revealed distinct ATP and DNA binding domains and the elastic network model identifies a functionally important hinge region between the two domains of pUL15. The atomic information on the active and allosteric sites in the ATP- and DNA-bound model of pUL15 presented in this study can inform the structure-based drug discovery of a new class of drugs to treat a wide range of HHVs.

Late-onset visceral varicella-zoster virus infection presented as acute liver failure after allogeneic hematopoietic stem cell transplantation

Although much less common than localized zoster, initial presentation of varicella-zoster virus (VZV) as visceral infection can occur especially after allogeneic hematopoietic stem cell transplantation (HSCT). We herein report a case of post-transplant visceral VZV infection presenting as fatal acute liver failure. It developed 4 years after allogeneic HSCT when a long-term prophylactic anti-VZV agent administration was discontinued. VZV should be listed as a causative pathogen of acute liver failure even years after allogeneic HSCT. Indication for, and duration of anti-VZV prophylaxis should be further investigated.

Current In Vivo Models of Varicella-Zoster Virus Neurotropism

Varicella-zoster virus (VZV), an exclusively human herpesvirus, causes chickenpox and establishes a latent infection in ganglia, reactivating decades later to produce zoster and associated neurological complications. An understanding of VZV neurotropism in humans has long been hampered by the lack of an adequate animal model. For example, experimental inoculation of VZV in small animals including guinea pigs and cotton rats results in the infection of ganglia but not a rash. The severe combined immune deficient human (SCID-hu) model allows the study of VZV neurotropism for human neural sub-populations. Simian varicella virus (SVV) infection of rhesus macaques (RM) closely resembles both human primary VZV infection and reactivation, with analyses at early times after infection providing valuable information about the extent of viral replication and the host immune responses. Indeed, a critical role for CD4 T-cell immunity during acute SVV infection as well as reactivation has emerged based on studies using RM. Herein we discuss the results of efforts from different groups to establish an animal model of VZV neurotropism.

Fatal disseminated visceral varicella zoster virus infection in a renal transplant recipient

We report a case of fatal disseminated varicella zoster virus (VZV) with delayed-onset rash in a 66-year-old female more than 2 years following uncomplicated deceased donor renal transplantation. Whilst on a stable regimen of maintenance immunosuppression, the patient presented with chest and abdominal pain with concomitant hepatitis and pancreatitis. After pursuing multiple other potential causes of her symptoms, the correct diagnosis of VZV was only suspected after the development of a widespread vesicular rash-11 days after her initial symptoms. Despite antiviral therapy and inotropic support in the intensive care unit, the patient died. Simultaneous VZV hepatitis and pancreatitis in solid organ transplant recipients is uncommon. The new inactivated VZV vaccines have the potential to prevent post-transplant infections, with promising early clinical data on safety and efficacy in renal transplant recipients. VZV is an important preventable infection that should be considered in immunocompromised patients, even in the absence of rash.

Varicella-Zoster Virus and the Enteric Nervous System

Varicella zoster virus (VZV) infects and becomes latent in sensory, enteric, and other autonomic neurons during the viremia of varicella. Reactivation of VZV in neurons that project to the skin causes the rash of zoster; however, reactivation of VZV in enteric neurons can cause a painful gastrointestinal disorder ("enteric zoster") without cutaneous manifestations. Detection of VZV DNA in saliva of patients with gastrointestinal symptoms may suggest enteric zoster. This diagnosis is reinforced by observing a response to antiviral therapy and can be confirmed by detecting VZV gene products in intestinal mucosal biopsies. We developed an in vivo guinea pig model that may be useful in studies of VZV latency and reactivation. VZV-infected lymphocytes are used to induce latent infection in sensory and enteric neurons; evidence suggests that exosomes and stimulator of interferon genes (STING) may, by preventing proliferation play roles in the establishment of neuronal latency.

Varicella-zoster virus-associated fulminant hepatitis following allogeneic hematopoietic stem cell transplantation for multiple myeloma

Disseminated visceral varicella-zoster virus (VZV) infection rarely occurs in recipients of allogeneic hematopoietic stem cell transplantation (allo-HSCT). To date, only a few cases of isolated VZV-induced fulminant hepatitis following allo-HSCT have been reported. We herein describe the case of a 47-year-old Japanese man with multiple myeloma who developed fulminant hepatitis 17 months after undergoing allo-HSCT. Despite receiving fresh frozen plasma and platelet transfusions, he developed a bleeding tendency (systemic purpura, petechiae and oral bleeding), slipped into a coma and eventually died. He was retrospectively diagnosed with viscerally disseminated VZV infection based on a postmortem examination and multiplex polymerase chain reaction (PCR) amplification.

Gastric ulcers due to varicella-zoster reactivation

We report on an 18-year-old man with common variable immunodeficiency presenting with abdominal pain and vomiting due to gastric ulcers caused by reactivation of varicella-zoster virus (VZV). Endoscopy revealed multiple ulcers in the gastric antrum. Fever and rash developed the next day. Skin biopsy showed multinucleated cells with intranuclear inclusions highly suggestive of VZV infection, and high-dose intravenous acyclovir was started. VZV was detected on direct immunofluorescence from skin biopsy and polymerase chain reaction from endoscopic biopsy. His course was complicated by encephalopathy, pancreatitis, hepatitis, renal impairment, and hyponatremia. After 3 weeks of antiviral therapy, he gradually improved. Skin lesions cleared within a week. He remained well on follow-up 1 year later. Disseminated zoster presenting as gastric ulcers in the absence of the classic rash is unusual but has been reported in immunosuppressed patients with a history of bone marrow and stem cell transplant. We report this rare presentation in a patient with common variable immunodeficiency and highlight the importance of considering zoster as a cause for severe abdominal pain and of seeking endoscopic diagnosis to facilitate early therapy and reduced mortality risk.

Persistence and antiviral resistance of varicella zoster virus in hematological patients

BACKGROUND

Varicella zoster virus (VZV) infections are a relevant cause of morbidity and mortality in hematological patients and especially in hematopoietic stem cell transplant (HSCT) recipients. The present study aimed to investigate the prevalence and clinical significance of viral persistence and antiviral resistance by systematically analyzing all episodes of VZV diagnosed in our laboratory in pediatric and adult hematological patients between 2007 and 2010.

METHODS

Patient charts were reviewed to document patient and disease characteristics. VZV loads were determined in all available clinical samples from the day of diagnosis and thereafter. Persistent VZV infection was defined as a VZV infection that lasted at least 7 days. Analysis of resistance was performed in all patients with persistent VZV infection by sequence analysis of viral thymidine kinase and DNA polymerase genes.

RESULTS

In total, 89 episodes occurred in 87 patients, of whom 65 were recipients of an allogeneic HSCT. Follow-up samples were available in 54 episodes. Persistent VZV was demonstrated in 32 of these episodes (59%). Complications occurred in 16 of the persistent episodes (50%) vs 2 of 22 nonpersistent episodes (9%). Mutations possibly associated with resistance were found in 27% of patients with persistent VZV, including patients with treatment-unresponsive dermatomal zoster that progressed to severe retinal or cerebral infection.

CONCLUSIONS

In hematological patients, VZV-related complications occur frequently, especially in persistent infections. Antiviral resistance is a relevant factor in persistent infections and needs to be investigated in various affected body sites, especially when clinical suspicion of treatment failure arises.

Cutaneous infections caused by Herpesviridae: a review

The herpes family of viruses accounts for a significant proportion of human cutaneous disease. Although most episodes of viral infection can be diagnosed clinically, a small subset of these outbreaks will require biopsy for histologic interpretation and diagnosis. Most herpesviruses cause characteristic architectural and cytologic changes in the context of active infection, whereas the effects of some will not manifest until the future as malignant disease. Other infections may go unnoticed secondary to a lack of specific histologic findings. Because herpesviruses cause such a wide spectrum of cutaneous conditions, it is prudent that pathologists be aware of the varied clinical and histopathologic presentations so that these infections will not persist undiagnosed. Additionally, methods of virus detection will briefly be reviewed.