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

Serological and T Cell Responses After Varicella Zoster Virus Vaccination in HIV-Positive Patients Undergoing Renal Dialysis

Limited data on varicella zoster virus (VZV) vaccine responses are available in HIV-positive adults, especially among those with end-stage renal disease on dialysis or undergoing kidney transplantation (KT). Serological and T cell responses were analyzed using anti-VZV IgG titers, enzyme-linked immunosorbent assay and flow cytometric intracellular cytokine staining (ICS) in two HIV-positive kidney transplant candidates undergoing dialysis and receiving VZV immunization. The results were compared with two HIV-positive and two HIV-negative VZV-seropositive patients (two kidney transplant candidates and two kidney transplant recipients), and with one HIV-negative vaccinee. HIV-positive VZV-susceptible patients received two doses of VZV vaccine 12 weeks apart. No adverse events were reported. Serological data were indicative of immunological response in one patient and corresponded to T cell responses. The second patient showed only a transient increase in anti-VZV IgG titers, but reported positive CD4⁺ T cell responses that were maintained after KT. Positive T cell and serological responses were detected in both HIV-positive and HIV-negative controls. VZV vaccination appeared safe and effective in HIV-positive KT candidates. VZV-specific T cell immunity was detected among transplant candidates and after KT. The assessment of VZV-specific T cell immunity using flow cytometric ICS may be more reliable compared to serology in assessing responses to VZV vaccine in this group.

Varicella zoster virus productively infects human natural killer cells and manipulates phenotype

Varicella zoster virus (VZV) is a ubiquitous human alphaherpesvirus, responsible for varicella upon primary infection and herpes zoster following reactivation from latency. To establish lifelong infection, VZV employs strategies to evade and manipulate the immune system to its advantage in disseminating virus. As innate lymphocytes, natural killer (NK) cells are part of the early immune response to infection, and have been implicated in controlling VZV infection in patients. Understanding of how VZV directly interacts with NK cells, however, has not been investigated in detail. In this study, we provide the first evidence that VZV is capable of infecting human NK cells from peripheral blood in vitro. VZV infection of NK cells is productive, supporting the full kinetic cascade of viral gene expression and producing new infectious virus which was transmitted to epithelial cells in culture. We determined by flow cytometry that NK cell infection with VZV was not only preferential for the mature CD56^dim NK cell subset, but also drove acquisition of the terminally-differentiated maturity marker CD57. Interpretation of high dimensional flow cytometry data with tSNE analysis revealed that culture of NK cells with VZV also induced a potent loss of expression of the low-affinity IgG Fc receptor CD16 on the cell surface. Notably, VZV infection of NK cells upregulated surface expression of chemokine receptors associated with trafficking to the skin –a crucial site in VZV disease where highly infectious lesions develop. We demonstrate that VZV actively manipulates the NK cell phenotype through productive infection, and propose a potential role for NK cells in VZV pathogenesis.

Varicella zoster virus (VZV) is a pervasive pathogen, causing chickenpox during primary infection and shingles when the virus reactivates from latency. VZV is therefore a lifelong infection for humans, warranting investigation of how this virus interacts with the immune system. One of the first immune cells to respond to viral infection are natural killer (NK) cells, yet little is known about how VZV interacts with NK cells. We demonstrate for the first time that VZV infects human blood NK cells and can use them to pass on infection to other cells in culture. Furthermore, VZV displays a predilection for infecting mature NK cells, and amplifies expression of receptors that would promote trafficking to the skin– the site of highly infectious lesions during chickenpox and shingles. Our findings suggest a role for NK cells in VZV disease and enhances our understanding of how lifelong infections interact with the human immune system.

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 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.

Early detection of Varicella-Zoster virus (VZV)-specific T-cells before seroconversion in primary varicella infection: case report

Here we report the case of a 54-year old, immunocompetent German patient with primary varicella whose Varicella-Zoster Virus (VZV)-specific T-cell responses could be detected early in infection and before the onset of seroconversion. This case demonstrates that the detection of VZV-specific T-cells may under certain circumstances support the diagnosis of a primary varicella infection, as for example in cases of atypical or subclinical varicella or in the absence of detectable VZV DNA in plasma.

Fatal varicella in an immunocompromised adult associated with a European genotype E2 variant of varicella zoster virus

Varicella zoster virus (VZV) seronegative patients under immunosuppressive therapy are at risk for severe life-threatening varicella. A 25-year-old male patient presented with rash and hepatitis. He had been known to suffer from Crohn's disease and received immunosuppressive treatment with azathioprine. The patient showed dyspnoea, and presented with a generalized rash with vesicular lesions typical for herpesvirus infections. He was started immediately on acyclovir therapy. Varicella infection was determined in this VZV seronegative patient in rash vesicles, blood and tracheal secretions and a high VZV viral load was detected in these specimens. The causative agent was genotyped by sequencing of several genes as a variant of the European genotype E2 containing several unique single nucleotide polymorphisms. Despite all measures, there was progressive septic shock, and the patient died due to multi-organ failure. Immunocompromised adults without varicella history are at high risk to develop life-threatening complications of varicella. Antiviral therapy with acyclovir can only be successful when administered as early as possible on suspicion of varicella infection in this group of patients. The most effective method to prevent severe varicella in immunocompromised patients is active immunization prior to immunosuppressive therapy.

Simian varicella in old world monkeys

Simian varicella virus (SVV) causes a natural erythematous disease in Old World monkeys and is responsible for simian varicella epizootics that occur sporadically in facilities housing nonhuman primates. This review summarizes the biology of SVV and simian varicella as a veterinary disease of nonhuman primates. SVV is closely related to varicella-zoster virus, the causative agent of human varicella and herpes zoster. Clinical signs of simian varicella include fever, vesicular skin rash, and hepatitis. Simian varicella may range from a mild infection to a severe and life-threatening disease, and epizootics may have high morbidity and mortality rates. SVV establishes a lifelong latent infection in neural ganglia of animals in which the primary disease resolves, and the virus may reactivate later in life to cause a secondary disease corresponding to herpes zoster. Prompt diagnosis is important for control and prevention of epizootics. Antiviral treatment for simian varicella may be effective if administered early in the course of infection.