The genomes of simian varicella virus and varicella zoster virus are colinear.

Simian varicella virus (SVV) causes an exanthematous disease in non-human primates which is clinically similar to varicella zoster virus (VZV) infection of humans. In this study, the genetic relatedness of SVV and VZV was confirmed and the location of SVV DNA sequences homologous to VZV restriction endonuclease (RE) fragments and viral genes was determined. VZV DNA RE fragments representing 98.3% of the VZV genome were 32P-labeled and hybridized to RE digested, immobilized SVV DNA. Homologous sequences were located throughout the viral DNAs in similar map positions, indicating a colinear relationship between the VZV and SVV genomes. 32P-labeled VZV glycoprotein (gp I, II, III, and IV) and gene 62 DNA probes also hybridized to SVV DNA in a colinear manner. The results suggest that the location of specific SVV genes may be predicted from the known map positions of homologous VZV genes. This study provides further support for SVV infection of non-human primates as a model for VZV infection of humans.     

Replication of varicella zoster virus in primary human keratinocytes.

The ability of varicella zoster virus (VZV) to infect and replicate in human keratinocytes in culture was examined. Primary human keratinocytes derived from the abdomen, breast, and foreskin were plated as monolayers and infected by co-cultivation with VZV infected fibroblasts (MRC-5 cells). Replication and spread of the virus was assayed by plaque assay and immunofluorescence of infected cells using a VZV specific monoclonal antibody. Although all three types of keratinocytes tested were capable of supporting productive VZV infection, the keratinocytes showed a 1.5 to 2 log reduction in virus yield as compared to infection of monolayer cultures of MRC-5 cells. Results from immunofluorescence studies and plaque assays indicate a slower rate of cell-to-cell spread of the virus. Testing of an anti-VZV compound in this novel assay system demonstrated an interesting sensitivity compared to that observed in conventional assay systems.     

The simian varicella virus and varicella zoster virus genomes are similar in size and structure.

Simian varicella virus (SVV) DNA was purified from viral nucleocapsids and the molecular structure of the SVV genome was determined. SVV DNA was analyzed by agarose gel electrophoresis of BamHI, BglII, EcoRI, and PstI restriction endonuclease digests. SVV and varicella zoster virus (VZV) DNAs were demonstrated to have distinct restriction endonuclease profiles. Summation of the sizes of individual restriction endonuclease fragments indicate the size of SVV DNA is congruent to 121 kilobase pairs (kbp) or congruent to 76.8 megadaltons (Md). Electron microscopy, lambda exonuclease analysis, and Southern blot DNA hybridizations were utilized to determine the molecular structure of the SVV genome and to construct restriction endonuclease maps. The results indicate that SVV DNA consists of a long component (L, congruent to 100 kbp) covalently linked to a short component (S, congruent to 20 kbp) which is composed of a unique short sequence (Us, 5.3 +/- 0.7 kbp) bracketed by inverted repeat sequences (TRs and IRs, congruent to 7.2 kbp). The presence of 0.5 M PstI restriction endonuclease fragments indicates that the S component may invert relative to the L component and that the genome exists in two major isomeric forms. The findings demonstrate that the SVV and VZV genomes are similar in size and structure.     

High-titre, cryostable cell-free varicella zoster virus

Summary.  Work with varicella-zoster virus has been seriously hampered by the difficulty of preparing high-titre cell free virus, and by the instability of such virus when frozen and thawed. We have evaluated the use of a range of protocols and demonstrate that relatively high titres of 19,000 plaque forming units per millilitre may be recovered after freezing in PBS-sucrose-glutamate-serum buffer (PSGC). In addition, we have shown that the virus obtained by this method gives similar results in neutralisation and antiviral susceptibility assays to that freshly prepared from infected cells, allowing the use of high titre, titrated virus stocks in such assays. Received August 25, 1997 Accepted January 8, 1998     

Chronic herpes simplex virus and varicella zoster virus infection

After defining such terms as persistent and chronic infection, latency, recurrence, recrudescence, and exogenous reinfection they are applied to infections with HSV and VZV. Possible factors determining pathogenicity are discussed, and an overview is given of the wide range of illnesses and case reports ascribed to HSV and VZV infections. Various types of infection afford different diagnostic procedures. Besides virus isolation supplemented by viral antigen identification IgG antibody tests (increase in titer) may be useful. IgG subtype and IgA antibody determinations appear to be of limited value. Despite the rather large number of available tests, there are still considerable shortcomings in their ultimate significance as to the patient's disease. Thus, some new experimental approaches are mentioned.     

Processing of virus-specific glycoproteins of varicella zoster virus

Monoclonal antibodies to varicella zoster virus (VZV) glycoproteins were used to study the processing of three glycoproteins with molecular weights of 83K-94K (gp 2), 64K (gp 3), and 55K (gp 5). Immunoprecipitation experiments performed with VZV-infected cells, pulse labeled with [3H]glucosamine in the presence of tunicamycin, suggest that O-linked oligosaccharide is present on the glycoprotein of gp 2. Use of the enzyme endo-beta-N-acetylglucosaminidase H revealed that the fully processed form of gp 3 had high-mannose type and that of gp 5 had only complex type of N-linked oligosaccharides. Experiments with monensin suggest that the precursor form (116K) of gp 3 is cleaved during the processing from Golgi apparatus to cell surface membrane. The extension of O-linked oligosaccharide chain and the complex type of N-linked oligosaccharide chains also occurs during this processing.     

Replication of varicella zoster virus in Raji cells

This report provides evidence for the replication of varicella zoster virus (VZV) in Raji cells. Infection was achieved by co-cultivation of Raji cells with VZV-infected human fibroblasts. Replication of VZV, as assessed by immunofluorescence using monoclonal antibodies against VZV-glycoproteins, ranged from 18 to 24% of the cells. Electron microscopy detected complete virions within the membrane-bound cytoplasmic vesicles and free viral particles in the nuclear matrix as late as 12 days post-infection. Western blot analysis of infected Raji cells demonstrated VZV-specific glycoproteins. The availability of a VZV-susceptible cell line growing in suspension culture provides a useful model for future studies.     

Varicella zoster virus: natural history and current therapies of varicella and herpes zoster

The natural history of varicella zoster virus (VZV) infection and the molecular mechanisms of viral pathogenesis are incompletely understood. Although no animal model yet reproduces all aspects of VZV infection, recently developed models of VZV infection, and the creation of genetically altered VZV recombinants, are yielding new information about primary viraemia and latency. During viraemia, T-cells transport VZV to the skin, where cell-free viral replication facilitates person-to-person spread and transmission to the neurons where latency is established. The alternate viral pathways of lytic infection or latency appear to be cell-type determined and involve both host and viral components. Antiviral therapy for varicella is safe and efficacious, and as varicella in children is usually mild, treatment is generally recommended only for adolescents and adults with varicella. Treatment is recommended for all individuals with herpes zoster, especially those aged over 50 years. For some varicella and zoster cases, aciclovir, the original standard, is being replaced by valaciclovir and famciclovir as preferred therapies. For herpes zoster, bromovinyl deoxyuridine (brivudin) has been added to the list of treatment options for immunocompetent individuals, but is contraindicated in patients with cancer. Antiviral therapy will still have a role in the treatment of disease caused by VZV even after the widespread implementation of vaccination programmes for both chickenpox and herpes zoster.     

Prevention of shingles by varicella zoster virus vaccination

Herpes zoster is caused by reactivation from previous varicella zoster virus (VZV) infection, and affects millions of people worldwide. It primarily affects older adults and those with immune system dysfunction, most likely as a result of reduced or lost VZV-specific cell-mediated immunity. Complications include post-herpetic neuralgia, a potentially debilitating and chronic pain syndrome. Current treatment of herpes zoster and post-herpetic neuralgia involves antiviral agents and analgesics, and is associated with significant economic cost. Results from several clinical trials have determined that a live, attenuated VZV vaccine using the Oka/Merck strain (Zostavax) is safe, elevates VZV-specific cell-mediated immunity, and significantly reduces the incidence of herpes zoster and post-herpetic neuralgia in people over 60 years of age. Regulatory approval has recently been obtained and once launched, it is expected that this vaccine will significantly reduce the morbidity and financial costs associated with herpes zoster. Durability of vaccine response and possible booster vaccination will still need to be determined.     

Acute central nervous system complications in varicella zoster virus infections.

BACKGROUND: In a previous multicenter study on central nervous system (CNS) viral infections varicella zoster virus (VZV) appeared the most frequent etiologic agent and appeared often without rash. OBJECTIVE: To evaluate the appearance and diagnostics of VZV in CNS more thoroughly, we studied the cases systematically by using sensitive and specific methods to learn the best diagnostic approach in order to start specific therapy. STUDY DESIGN: We analyzed all serum and cerebrospinal fluid samples of 174 patients, 88 females and 86 males, with acute CNS symptoms associated with VZV infection diagnosed in the multicenter study on viral CNS infections. RESULTS: About 38 patients (22%) had chickenpox, 59 (34%) had shingles, and 77 (44%) had no cutaneous symptoms at all. The mean age of chickenpox patients was 8.6 years, of the others 46.6 and 41.4 years. VZV-specific nucleic acid was detected in the CSF in one fourth of the patients in all groups, primarily during the first week of illness. In serum specimens, specific IgM was present in two thirds of the patients with chickenpox, whereas in the others in one third of the cases. In CSF, specific IgM was present in 15-17% of patients with skin manifestations, compared with 6% of those without rash. CONCLUSIONS: The role of VZV infections in CNS complications seems remarkable, often presenting without rash. Even these cases should be promptly recognized in order to conduct proper antiviral therapy. In children, a combination of PCR and IgM tests is the best approach. In adults, PCR, together with the measurement of intrathecal antibody production yields best results.     

Natural and artificial immunity to varicella zoster virus

The live varicella vaccine has been recommended for use in immunocompromised subjects and in adults who are susceptible to chickenpox. However, we do not know how humoral and cell-mediated immune responses induced after vaccination differed from those obtained after natural infection. To answer this, 45 previously infected subjects (23 chickenpox, 22 vaccinated) were tested for their varicella zoster virus (VZV)-specific antibody levels and for their lymphocyte stimulation responses to VZV antigen. Antibody was measured by both an enzyme-linked immunosorbent assay (ELISA) and an immunofluorescence assay (IF), while lymphocyte stimulation was detected by tritiated thymidine incorporation. Antibody was tested in ten postchickenpox and nine vaccinated subjects. About 6 to 8 weeks after first exposure, the magnitude of the responses determined by both ELISA and IFT were much higher in the naturally infected than in the vaccinated group (P less than 0.001) with both test methods). There was no significant difference in the lymphocyte transformation responses in both groups of subjects. Thirteen postchickenpox and 13 vaccinated subjects who had been infected at least 12 months previously were also tested. Total antibody levels were again significantly higher in the naturally infected than in the vaccinated group (P less than 0.001). One vaccinated subject had VZV-specific IgA and IgM in the serum. The magnitude of the lymphocyte transformation reaction was higher in the naturally infected than in the vaccinated group (P less than 0.01). Thus, antibody responses to VZV were better in naturally infected than in vaccinated subjects. The IFT appears to be a more sensitive technique for antibody detection in the vaccinated subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Three cases of varicella thrombophlebitis as a complication of varicella zoster virus infection

Three cases of deep venous thrombosis following varicella infection are described which were successfully treated with bed rest and anticoagulants. Two of these patients had severe pulmonary manifestations of varicella and the third was complicated by pulmonary embolism. Deep vein thrombosis is an uncommon systemic manifestation of varicella, possibly associated with vascular endothelium wall damage caused by varicella zoster virus infection.     

Distribution of varicella zoster virus and herpes simplex virus in disseminated fatal infections.

AIMS: To study the cutaneous and visceral distribution of herpes simplex virus (HSV) and varicella zoster virus (VZV) in fatal infections. METHODS: Standard histology, immunohistochemistry (monoclonal antibodies VL8 and VL2 and polyclonal antibody IE63 directed against VZV; monoclonal antibodies IBD4 and HH2 and polyclonal antibodies directed against HSVI and HSVII) and in situ hybridisation (anti-HSV and anti-VZV probes) were applied to formalin fixed, paraffin wax sections. RESULTS: On histological examination, Herpesviridae infection was evident in various organs including the lungs, liver and skin. In addition, immunohistochemistry and in situ hybridisation revealed the presence of HSV and VZV antigens and nucleic acids in several cell types and tissues showing no cytopathological alterations suggestive of Herpesviridae infection. The organs with histological evidence of infection also contained VZV or HSV antigens and their genes. CONCLUSIONS: These findings suggest that organ failure in disseminated VZV and HSV infections is primarily caused by HSV or VZV induced cell damage and lysis. They also indicate that immunohistochemistry and in situ hybridisation can provide an accurate, type-specific diagnosis on formalin fixed, paraffin wax embedded tissue even when classic histological and cytological characteristics are lacking.     

Stress-induced subclinical reactivation of varicella zoster virus in astronauts

Varicella zoster virus (VZV) becomes latent in human ganglia after primary infection. VZV reactivation occurs primarily in elderly individuals, organ transplant recipients, and patients with cancer and AIDS, correlating with a specific decline in cell-mediated immunity to the virus. VZV can also reactivate after surgical stress. The unexpected occurrence of thoracic zoster 2 days before space flight in a 47-year-old healthy astronaut from a pool of 81 physically fit astronauts prompted our search for VZV reactivation during times of stress to determine whether VZV can also reactivate after non-surgical stress. We examined total DNA extracted from 312 saliva samples of eight astronauts before, during, and after space flight for VZV DNA by polymerase chain reaction: 112 samples were obtained 234-265 days before flight, 84 samples on days 2 through 13 of space flight, and 116 samples on days 1 through 15 after flight. Before space flight, only one of the 112 saliva samples from a single astronaut was positive for VZV DNA. In contrast, during and after space flight, 61 of 200 (30%) saliva samples were positive in all eight astronauts. No VZV DNA was detected in any of 88 saliva samples from 10 healthy control subjects. These results indicate that VZV can reactivate subclinically in healthy individuals after non-surgical stress.     

Genotyping of varicella zoster virus strains isolated in Mongolia

This study analyzed 50 varicella zoster virus (VZV) samples collected during 2004 to 2007 from patients with VZV infection, who were treated at the National Center of Communicable Diseases, Ulan-Bator, Mongolia. The method based on amplification of specific DNA fragments of the ORF21, ORF22, and ORF50 genes was used, followed by the sequencing and detection of the status of characteristic point mutations in these fragments. The results indicated that the collected samples belonged to genotypes J (62%), M1 (18%), E1 (12%), E2 (4%), and M2 (4%). Moreover, restriction endonuclease polymorphism in ORF 62 for the cleavage site Smal and Mspl, in ORF 38 and ORF 54 for the cleavage site Pstl and Bgll were analyzed. All the samples were Sma- Msp-. All samples with genotype E were Pst+ Bgl-; all samples with genotype M1 and M2 were Pst+ Bgl+. Out of 31 samples with genotype J, 29 and 2 were Pst+ Bgl+ and Pst+ Bgl+, respectively. The study could identify the genotypes of VZV circulating in Mongolia and confirmed the absence of mutations characteristic for the vaccine strain.     

Frequency and specificity of varicella zoster virus IgM response

A direct ELISA was developed for determination of IgM antibody to varicella zoster virus (VZV). With this sensitive method VZV IgM antibodies were detected in all patients with a varicella and in 84% with a herpes zoster infection. All but one of 28 renal allograft recipients had previously had varicella. A primary infection was seen in the last patient, and reactivated infections in 11 of the others. The VZV IgM response seems to be specific since patients with a herpes simplex virus (HSV) infection and a heterotypic VZV IgG titer rise did not have detectable VZV IgM. An indirect enzyme-linked immunosorbent assay (ELISA) for detection of IgG antibodies has been used for serodiagnosis of VZV infections and to determine the immune status. After injection of zoster immune globulin, it was possible to measure passively transferred antibodies.     

Lymphocyte responses to varicella zoster virus in the elderly

Elderly subjects (age 75–95 years) immune to varicella zoster virus (VZV) were identified by the presence of serum IgG antibody. The frequency of lymphocytes in their blood which proliferated in varicella zoster virus antigen-stimulated cultures was 1:78,000±6600. This is less than the 1:14,000±2000 frequency of VZV-responsive lymphocytes in blood from younger adult (20–43 years) donors. Elderly donors' blood mononuclear cells were less efficient than those of younger adults at lysing VZV-infected fibroblasts but not K562 target cells. The lysis of VZV target cells by elderly donors' MNC increased to control levels in the presence of 10 U/ml of interleukin-2 (IL-2). These results suggest that mononuclear cells capable of killing VZV-infected target cells persist with aging but that reduced numbers of antigenresponsive and lymphokine-releasing T cells may limit their function.     

Immunity to varicella zoster virus in children with leukaemia

A total of 46% (32/70) of children with acute lymphoblastic leukaemia presenting to the Hospital for Sick Children had a past history of chickenpox. When their immunity to varicella zoster virus (VZV) was assessed, 75% (24/32) had a positive lymphocyte transformation response to VZV antigen in tissue culture while 78% (25/32) possessed IgG antibody against VZV. Therefore, at least 22% of the children were probably susceptible to infection with VZV inspite of having a history suggestive of chickenpox.Of those with a negative or uncertain history 34% had a positive lymphocyte transformation response, while 55% (21/38) had IgG antibody against VZV. Therefore, about one in two of those with a negative history to VZV had some form of immunity to VZV. Hence, regardless of their VZV infection history, children with leukaemia would need to undergo both cell mediated and humoral immunity tests before they may be considered for immunisation with the live varicella vaccine. From our studies, 34% (24/70) of our patients did not have any evidence of immunity to VZV by either test method. These would be considered for immunisation with the live varicella vaccine.