Herpes zoster and the immunocompromised

Simian Varicella Virus Is Present in Macrophages, Dendritic Cells, and T Cells in Lymph Nodes of Rhesus Macaques after Experimental Reactivation

Like varicella-zoster virus (VZV), simian varicella virus (SVV) reactivates to produce zoster. In the present study, 5 rhesus macaques were inoculated intrabronchially with SVV, and 5 months later, 4 monkeys were immunosuppressed; 1 monkey was not immunosuppressed but was subjected to the stress of transportation. In 4 monkeys, a zoster rash developed 7 to 12 weeks after immunosuppression, and a rash also developed in the monkey that was not immunosuppressed. Analysis at 24 to 48 h after zoster revealed SVV antigen in the lung alveolar wall, in ganglionic neurons and nonneuronal cells, and in skin and in lymph nodes. In skin, SVV was found primarily in sweat glands. In lymph nodes, the SVV antigen colocalized mostly with macrophages, dendritic cells, and, to a lesser extent, T cells. The presence of SVV in lymph nodes, as verified by quantitative PCR detection of SVV DNA, might reflect the sequestration of virus by macrophages and dendritic cells in lymph nodes or the presentation of viral antigens to T cells to initiate an immune response against SVV, or both.

IMPORTANCE

VZV causes varicella (chickenpox), becomes latent in ganglia, and reactivates to produce zoster and multiple other serious neurological disorders. SVV in nonhuman primates has proved to be a useful model in which the pathogenesis of the virus parallels the pathogenesis of VZV in humans. Here, we show that SVV antigens are present in sweat glands in skin and in macrophages and dendritic cells in lymph nodes after SVV reactivation in monkeys, raising the possibility that macrophages and dendritic cells in lymph nodes serve as antigen-presenting cells to activate T cell responses against SVV after reactivation.

Latent simian varicella virus reactivates in monkeys treated with tacrolimus with or without exposure to irradiation

Simian varicella virus (SVV) infection of primates resembles human varicella-zoster virus (VZV) infection. After primary infection, SVV becomes latent in ganglia and reactivates after immunosuppression or social and environmental stress. Herein, natural SVV infection was established in 5 cynomolgus macaques (cynos) and 10 African green (AG) monkeys. Four cynos were treated with the immunosuppressant tacrolimus (80 to 300 μg/kg/day) for 4 months and 1 was untreated (group 1). Four AG monkeys were exposed to a single dose (200 cGy) of x-irradiation (group 2), and 4 other AG monkeys were irradiated and treated with tacrolimus for 4 months (group 3); the remaining 2 AG monkeys were untreated. Zoster rash developed 1 to 2 weeks after tacrolimus treatment in 3 of 4 monkeys in group 1, 6 weeks after irradiation in 1 of 4 monkeys in group 2, and 1 to 2 weeks after irradiation in all 4 monkeys in group 3. All monkeys were euthanized 1 to 4 months after immunosuppression. SVV antigens were detected immunohistochemically in skin biopsies as well as in lungs of most monkeys. Low copy number SVV DNA was detected in ganglia from all three groups of monkeys, including controls. RNA specific for SVV ORFs 61, 63, and 9 was detected in ganglia from one immunosuppressed monkey in group 1. SVV antigens were detected in multiple ganglia from all immunosuppressed monkeys in every group, but not in controls. These results indicate that tacrolimus treatment produced reactivation in more monkeys than irradiation and tacrolimus and irradiation increased the frequency of SVV reactivation as compared to either treatment alone.

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.

Simian varicella virus reactivation in cynomolgus monkeys

SVV infection of primates closely resembles VZV infection of humans. Like VZV, SVV becomes latent in ganglionic neurons. We used this model to study the effect of immunosuppression on varicella reactivation. Cynomolgus monkeys latently infected with SVV were irradiated and treated with tacrolimus and prednisone. Of four latently infected monkeys that were immunosuppressed and subjected to the stress of transportation and isolation, one developed zoster, and three others developed features of subclinical reactivation. Another non-immunosuppressed latently infected monkey that was subjected to the same stress of travel and isolation showed features of subclinical reactivation. Virus reactivation was confirmed not only by the occurrence of zoster in one monkey, but also by the presence of late SVV RNA in ganglia, and the detection of SVV DNA in non-ganglionic tissue, and SVV antigens in skin, ganglia and lung.

Oral antivirals revisited in the treatment of herpes zoster: what do they accomplish?

Oral antiviral agents currently represent the most important therapeutic keystone in the treatment of herpes zoster. Three oral antiviral agents are available for the treatment of herpes zoster: acyclovir, its derivative valacyclovir, and famciclovir. Meta-analysis of published data has shown that oral acyclovir significantly reduces various herpes zoster-related symptoms as well as the duration, intensity and prevalence of zoster-associated pain (ZAP). However, this drug does not influence postherpetic neuralgia. The newer agents famciclovir and valacyclovir exhibit a better oral bioavailability than acyclovir. These agents have demonstrated similar efficacy to acyclovir with ZAP and they require less frequent administration. When initiated within 72 hours, oral antiviral therapy of herpes zoster is beneficial in selected, elderly immunocompetent patients, reducing the duration and intensity of ZAP and providing more rapid skin lesion healing. Oral antivirals are also of benefit in immunocompromised patients with uncomplicated herpes zoster. However, signs of cutaneous and visceral dissemination should be monitored; if signs occur, intravenous antiviral therapy is indicated.

Epidemic of herpes zoster following HIV epidemic in Manipur, India

Since 1989, injecting drug use (IDU) related HIV infection has affected thousands of young adults in Manipur, a north eastern state of India bordering Myanmar following a similar kind of epidemic in adjoining countries like Thailand and Myanmar. During a clinical surveillance of a group of HIV positive IDUs for a natural history study at Manipur, herpes zoster (HZ) emerged as the most specific early HIV related illness (positive predictive value of 100%) in patients belonging to the age group of 12-45 years. Data collected from the dermatology departments of the two main hospitals of the state revealed that there had been an epidemic of HZ since 1990 (rate of 1990 being 11.3/1000 compared to 6.5/1000 in 1989, P value < 0.0001) among males of 12-45 years. The epidemic of HZ has been attributed to the preceding epidemic of IDU related HIV in the same age and gender group occurring 1 year earlier. HZ should be recognised as a marker condition similar to tuberculosis indicating the necessity of screening for HIV in regions where the dual problem of IDU and HIV exist in young adults.

Clinical features of human immunodeficiency virus-associated disseminated herpes zoster virus infection--a review of the literature

Some similarities and several differences in the epidemiological, morphological, therapeutic, and prognostic features of HIV-associated disseminated HZV infection and disseminated HZV infection occurring in HIV-seronegative immunosuppressed patients exist. The severity of the cutaneous disseminated HZV infection, the potential for significant HZV-related morbidity, and the poor prognosis associated with this infection in HIV-seropositive patients, warrants prompt therapeutic intervention. The emergence of acyclovir-resistant HZV infection emphasizes the importance of continued investigation of alternative therapies for individuals with coincident HIV infection.

Epidemiology in general practice

Epidemiology in Country Practiceby William N. Pickles, published in 1939, has been a source of continuing interest and challenge especially to general practitioners (Watson, 1982; Booth, 1987). Pickles worked for over 50 years as a general practitioner (GP) in rural Wensleydale where there were many isolated villages in which natural immunity against various infections was often lacking. And so the source of infection could usually be traced, and, with little or no immunity, spread was often rapid.

Severe and recurrent varicella-zoster virus infection in a patient with the acquired immune deficiency syndrome

We report a case of recurrent varicella-zoster virus infection in a patient with severe acquired immune deficiency syndrome in whom the infection has become clinically unresponsive to treatment with acyclovir.