Transcription factor Sp1 is involved in the regulation of varicella-zoster virus glycoprotein E

Varicella-zoster virus glycoprotein E (ORF 68) belongs to the group of late genes. It is a major component of the virion envelope and can be found complexed with glycoprotein I on the infected host cell surface. Glycoprotein E (gE) expression is activated by IE4 and IE62. Also, cellular transcription factors, like Sp1, are able to influence the gE expression. Performing quantitative reverse transcription-polymerase chain reaction, we found no decrease in Sp1 mRNA levels at different times post-infection, indicating that Sp1 mRNA evade virion host shutoff effects. In addition, the Sp1 protein was detectable in highly infected cells. Electrophoretic mobility shift assays have shown a binding of Sp1 to both GC elements within the gE-5'untranslated region (5'UTR). Additional shift assays have notified a binding of TATA box binding protein to the TATA box of the gE promoter, which is characterized by an untypical TATACA motif. Promoter-reporter constructs have been made using mutated variants of the gE-5'UTR as promoters. In transfection studies, we found that the TATA deletion, as well as inactivations of both GC boxes, reduced the basal activity of the promoter. A complete loss of activity did not become measurable until eliminating both GC elements and the TATA box, indicating that these cis-elements substitute for each other in initiation of transcription of the gE-5'UTR.

Diagnostic utility of a multiplex herpesvirus PCR assay performed with cerebrospinal fluid from human immunodeficiency virus-infected patients with neurological disorders

We used a multiplex nested-PCR assay for the simultaneous detection in cerebrospinal fluid (CSF) of five human herpesviruses (HVs) (cytomegalovirus [CMV], Epstein-Barr virus [EBV], varicella-zoster virus [VZV], herpes simplex virus [HSV], and human herpesvirus 6 [HHV-6]) in a clinical evaluation of human immunodeficiency virus (HIV)-infected patients with neurological disorders. This method, which has the advantages of being rapid and economical, would be of particular interest for the diagnosis of neurological syndromes caused by more than one HV. We studied 251 CSF samples from 219 patients. HV DNA was demonstrated in 93 (37%) of the CSF samples (34% of the patients). CMV was the HV most frequently detected in our patients (25%), while EBV, VZV, HSV, and HHV-6 DNAs were present in significantly fewer cases (7, 4, 3, and 1%, respectively). When results were compared with the final etiological diagnoses of the patients, the multiplex HV PCR showed high specificity for the diagnosis of CMV and VZV neurological diseases and for cerebral lymphoma (0.95, 0.97, and 0.99, respectively). The sensitivity of the assay was high for CMV disease (0.87), was low for cerebral lymphoma (0.33), and was not evaluable for VZV disease due to the small number of patients with this diagnosis. Nevertheless, detection of VZV DNA had possible diagnostic value in four of the nine cases, and EBV DNA amplification always predicted the diagnosis of cerebral lymphoma in patients with cerebral masses. Detection of HSV DNA was frequently associated with CMV amplification and fatal encephalitis. HHV-6 was not considered to have a pathogenetic role in the three cases in which it was detected. This multiplex HV PCR assay is a specific and clinically useful method for the evaluation of HIV-infected patients with neurological disorders related to HV.

Comparison between of the attenuated BR-Oka and the wild type strain of Varicella Zoster Virus (VZV) on the DNA level

Oka strain VR-795 (Varicella Zoster Virus, VZV) of American Type Culture Collection (ATCC) has been used for chickenpox vaccine production. In order to use this strain for vaccine production, the strain must be identified and its stability must be confirmed. The identification of the Oka strain has been confirmed using Restriction Fragment Length Polymorphism (RFLP) and DNA sequence analysis of glycoprotein-II (gp-II). The amino acid sequences of Oka deduced from the DNA sequence of gp-II have changed at three amino acids against Ellen and at one amino acid against Webster. To prove the stability of the Oka strain during the passage, RFLP and DNA sequence analyses were also used with 11, 15 and 23 times of virus passage. We found that the Oka strain was stable at passages of up to 23 times, based on the RFLP and DNA sequence analyses. The confirmed Oka strain was renamed as BR-Oka for the purposes of chickenpox vaccine production.

[Detection of varicella-zoster virus DNA in tear fluid and saliva of patients with Ramsay Hunt syndrome]

Ramsay Hunt syndrome develops when the varicella-zoster virus (VZV) is reactivated. In the present study, we examined the secretion kinetics of VZV DNA in the tear fluid, submandibular gland saliva and parotid gland saliva of 15 patients with Ramsay Hunt syndrome. The presence of VZV DNA was detected using PCR and a microplate hybridization method. Hybridization signals were measured using the fluorescence density of an enzymatic reaction product using fluoroscan and a system involving streptavidin-conjugated beta-galactosidase. The results were converted into numerical values and used to estimate the number of virus DNA copies. VZV DNA was detected in the tear fluid, submandibular gland saliva and parotid gland saliva of the Ramsay Hunt syndrome patients. The rate of VZV DNA detection in the submandibular gland saliva was 72%, and the detection rate in the parotid gland saliva was 57%. The detection rate in the tear fluid was 27%, which is significantly lower than other two detection rates. Regarding the submandibular gland saliva and the parotid gland saliva, the VZV DNA was detected in samples collected at a comparatively early stage of onset. In the tear fluid, the detection rate increased significantly in samples collected 2 weeks after onset or later. Thus, differences in the detection rate were observed depending on the type of secretory gland and the timing of the sample collection. The VZV DNA in the tear fluid is thought to derive from the ganglion trigeminale. The increase and decrease in the number of VZV DNA copies detected in samples collected at different times is considered to substantiate VZV reactivation in Ramsay Hunt syndrome.

Oka varicella vaccine is distinguishable from its parental virus in DNA sequence of open reading frame 62 and its transactivation activity

When the nucleotide sequences of the Oka vaccine and its parental varicella-zoster virus (VZV) were compared in 6 open reading frames (ORFs), glycoprotein C (gC) and 5 transactivator genes, mutations were detected only in the immediate-early gene 62. The vaccine virus contained a mixture of different sequences that had variations at 15 nucleotide positions, but only one sequence was found for the Oka parental virus gene 62. The Oka vaccine virus gene 62 could be distinguished from the parental virus gene using a simplified restriction-enzyme fragment length polymorphism analysis, using NaeI and BssHII. This analysis was based on the sequence data obtained in this study. Studies of the regulatory activities of the ORF62 gene product (IE62) in a transient transfection assay indicated that IE62 of the parental virus had a stronger transactivational activity than that of the vaccine virus in activating immediate-early, early, and late gene promoters. These data suggest that IE62 might play an important role in the attenuation of VZV.

Physical interaction between two varicella zoster virus gene regulatory proteins, IE4 and IE62

Transfection assays demonstrate that the varicella zoster virus (VZV) immediate-early 62 (IE62) protein is a major transactivator of VZV gene expression, whereas a second immediate-early protein, IE4, can act as a major coactivator of transactivation mediated through IE62. To test whether IE62 and IE4 interact physically, we performed several protein-protein interaction assays. Coimmunoprecipitation analyses using VZV-infected cell lysates as well as purified protein mixtures demonstrate that IE62 and IE4 form stable complexes in solution under stringent salt conditions. Enzyme-linked immunosorbent assay protein-protein interaction assays and maltose-binding protein capture assays demonstrate that IE62 binds IE4 in a concentration- and dose-dependent manner. Far Western blot analyses show that IE4 binds to an undermodified form of IE62, and the use of calf intestinal phosphatase and protein kinases suggests that the interaction with IE4 is dependent on the phosphorylation state of IE62. An IE4 binding domain on IE62 has been mapped using a set of truncated IE62 fusion peptides. Collectively, these results imply a direct and specific physical interaction between IE4 and less-phosphorylated forms of IE62. These data have implications for virion assembly, as well as for the regulation of gene expression in VZV-infected cells.

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

We describe a highly sensitive assay for quantitation of varicella-zoster virus (VZV) DNA in blood, involving PCR amplification, solution hybridization with Tris-(2, 2'-bipyridine)-ruthenium(II) chelate-labeled probes, and measurement by electrochemiluminescence (ECL). Extraction and amplification efficiencies were monitored by the inclusion of internal control (IC) DNA, mimicking the VZV target, in the DNA extraction. Viral DNA load was calculated from the ratio of VZV and IC ECL signals. The lower limit of sensitivity was 20 VZV DNA copies/ml of plasma or serum and 80 copies/ml of whole blood. In reconstruction experiments, expected and calculated VZV DNA loads were in excellent accordance. Blood specimens from 42 VZV-infected patients were tested for the presence of VZV DNA and showed detection rates of 86% in patients with varicella and 81% in patients with herpes zoster. In specimens obtained during the first week after onset of the rash, detection rates were 100 and 89%, respectively. Viral DNA was detected in all immunocompromised patients with herpes zoster, emphasizing the risk of disseminated disease in this patient group. VZV DNA load was similar in patients with varicella and multidermatomal herpes zoster and lower in patients with unidermatomal zoster. Despite the cell-associated nature of the virus, VZV DNA was detected in serum and plasma at high copy numbers, and at similar frequencies compared to whole-blood specimens. Quantitation of VZV DNA in blood is of potential importance for diagnosis and clinical management of VZV-infected patients. Plasma and serum provide convenient matrices for this purpose.

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

We describe a highly sensitive assay for quantitation of varicella-zoster virus (VZV) DNA in blood, involving PCR amplification, solution hybridization with Tris-(2, 2'-bipyridine)-ruthenium(II) chelate-labeled probes, and measurement by electrochemiluminescence (ECL). Extraction and amplification efficiencies were monitored by the inclusion of internal control (IC) DNA, mimicking the VZV target, in the DNA extraction. Viral DNA load was calculated from the ratio of VZV and IC ECL signals. The lower limit of sensitivity was 20 VZV DNA copies/ml of plasma or serum and 80 copies/ml of whole blood. In reconstruction experiments, expected and calculated VZV DNA loads were in excellent accordance. Blood specimens from 42 VZV-infected patients were tested for the presence of VZV DNA and showed detection rates of 86% in patients with varicella and 81% in patients with herpes zoster. In specimens obtained during the first week after onset of the rash, detection rates were 100 and 89%, respectively. Viral DNA was detected in all immunocompromised patients with herpes zoster, emphasizing the risk of disseminated disease in this patient group. VZV DNA load was similar in patients with varicella and multidermatomal herpes zoster and lower in patients with unidermatomal zoster. Despite the cell-associated nature of the virus, VZV DNA was detected in serum and plasma at high copy numbers, and at similar frequencies compared to whole-blood specimens. Quantitation of VZV DNA in blood is of potential importance for diagnosis and clinical management of VZV-infected patients. Plasma and serum provide convenient matrices for this purpose.

Characterization of interaction of gH and gL glycoproteins of varicella-zoster virus: their processing and trafficking

Varicella-zoster virus (VZV) glycoproteins gH and gL were examined in a recombinant vaccinia virus system. Single expression of glycoprotein gL produced two molecular forms: an 18 kDa form and a 19 kDa form differing in size by one endoglycosidase H-sensitive N-linked oligosaccharide. Coexpression of gL and gH resulted in binding of the 18 kDa gL form with the mature form of gH, while the 19 kDa gL form remained uncomplexed. The glycosylation processing of gL was not dependent on gH; however, gL was required for the conversion of precursor gH (97 kDa) to mature gH (118 kDa). Subsequent analyses indicated that gL (18 kDa) was a more completely processed gL (19 kDa). Screening of the culture media revealed that gH and gL were secreted, but only if coexpressed and complexed together. The secreted form of gL was 18 kDa while that of gH was 114 kDa. The fact that secreted gH was smaller than intracytoplasmic gH suggested a proteolytic processing event prior to secretion. The 19 kDa form of gL was never secreted. These findings support a VZV gL recycling pathway between the endoplasmic reticulum and the cis-Golgi apparatus.

Zoster sine herpete with bilateral ocular involvement

PURPOSE

To report a case of zoster sine herpete with bilateral ocular involvement.

METHOD

Case report.

RESULTS

A 65-year-old man showed bilateral iridocyclitis with sectoral iris atrophy and elevated intraocular pressure unresponsive to steroid treatment. No cutaneous eruption was manifest on the forehead. A target region of varicella-zoster virus DNA sequence was amplified from the aqueous sample from the left eye by polymerase chain reaction. Bilateral iridocyclitis resolved promptly after initiation of systemic and topical acyclovir treatment. Secondary glaucoma was well controlled by bilateral trabeculectomy.

CONCLUSIONS

Zoster sine herpete should be considered and polymerase chain reaction performed on an aqueous sample to detect varicella-zoster virus DNA for rapid diagnosis whenever anterior uveitis accompanies the characteristic iris atrophy, even in the case of bilateral involvement.

Anterior uveitis with sectoral iris atrophy in the absence of keratitis: a distinct clinical entity among herpetic eye diseases

OBJECTIVE

To determine the cause and describe the clinical features of unilateral anterior uveitis with sectoral atrophy of the iris in the absence of associated keratitis.

DESIGN

Retrospective, observational case series.

PARTICIPANTS

Thirty-one patients with unilateral anterior uveitis with sectoral iris atrophy and without (previous) keratitis.

METHODS

The patients were selected from our database of 592 patients with anterior uveitis.

MAIN OUTCOME MEASURES

We reviewed the clinical data on the 31 patients and the results of diagnostic anterior chamber fluid analysis for 24 of the 31 patients. Specifically, production of local antibodies against herpes simplex virus (HSV) and varicella zoster virus (VZV) was determined and the polymerase chain reaction was performed to demonstrate the DNA of HSV, VZV, and cytomegalovirus (CMV) in the aqueous samples.

RESULTS

Main clinical characteristics of anterior uveitis with iris atrophy included unilateral involvement with a prolonged course and recurrent exacerbations in all cases. Elevated intraocular pressure during intraocular inflammation occurred in 90% of patients (28 of 31). Visual outcome was favorable because 29 of 31 patients (94%) retained a visual acuity of 20/32 or more. The causal agent was identified as HSV in 83% (20 of 24) and VZV in 13% (3 of 24) and was inconclusive in one case. The patients with HSV uveitis were younger than those with VZV uveitis (mean age at onset 34 and 65 years, respectively; P = 0.0056).

CONCLUSIONS

Unilateral anterior uveitis with sectoral atrophy of the iris without associated (previous) keratitis is a distinct entity among herpetic eye diseases. Recurrent unilateral anterior uveitis with iris atrophy and/or elevated intraocular pressure has most likely been caused by HSV.

Characterization of acyclovir susceptibility and genetic stability of varicella-zoster viruses isolated during acyclovir therapy

We have characterized the susceptibility and genetic stability of varicella-zoster viruses (VZV) isolated from skin lesions of three patients with herpes zoster and six patients with varicella treated with conventional short-term acyclovir (ACV) administration. The susceptibilities to ACV of the serial isolates from the patients were examined, and there was no significant difference in the susceptibility to ACV among the isolates before and during the ACV treatment, indicating that conventional short-term ACV treatment did not generate ACV-resistant VZV infections. Polymerase chain reaction (PCR) analyses of these as well as seven thymidine kinase-deficient VZV strains derived from in vitro ACV treatment were carried out to examine their genomic stability. Five regions containing tandem direct reiterations (R1-R5) were amplified by PCR and compared, and the region containing the Pst I-site was also examined. PCR analyses demonstrated that the R1, R5 and the Pst I-sites were stable and useful in epidemiological studies even after ACV treatment. The R2, R3 and R4 sites were far less stable in these experimental conditions. In this paper we discuss the results of the PCR analyses with regard to the dynamics of VZV population in patients with VZV infection treated with conventional short-term ACV administration.

Rapid phenotypic characterization method for herpes simplex virus and Varicella-Zoster virus thymidine kinases to screen for acyclovir-resistant viral infection

A rapid phenotypic screening method for herpes simplex virus (HSV) and varicella-zoster virus (VZV) thymidine kinase (TK) genes was developed for monitoring acyclovir-resistant viruses. This method determines the biochemical phenotype of the TK polypeptide, which is synthesized in vitro from viral DNA using a procedure as follows. The TK gene of each sample virus strain is amplified and isolated under the control of a T7 promoter by PCR. The PCR products are transcribed with T7 RNA polymerase and translated in a rabbit reticulocyte lysate. Using this method, enzymatic characteristics and the size of the TK polypeptides encoding HSV and VZV DNA were defined in less than 2 days without virus isolation. The assay should be a powerful tool in monitoring drug-resistant viruses, especially in cases in which virus isolation is difficult.

A rapid phenotypic assay for detection of acyclovir-resistant varicella-zoster virus with mutations in the thymidine kinase open reading frame

Susceptibility assays by cell culture methods are time-consuming and are particularly difficult to perform with varicella-zoster virus (VZV). To overcome this limitation, we have adapted a functional test of the viral thymidine kinase (TK) in TK-deficient (tdk mutant) bacteria to detect ACV-resistant VZV in clinical samples. After PCR amplification, the complete viral TK open reading frame (ORF) is purified from PCR primers, digested with two restriction enzymes, and ligated in an oriented fashion into a bacterial expression vector. The ligation products are then used to transform tdk mutant bacteria. After transformation, an aliquot of the bacteria is plated onto a plate with minimal medium containing (i) ampicillin to select for plasmids carrying the viral TK ORF and (ii) isopropyl beta-D-thiogalactopyranoside (IPTG) to induce its expression. An identical aliquot of bacteria is also plated onto a medium containing, in addition to the components described above, 5-fluorodeoxyuridine (FUdR). Compared to the number of transformants on FUdR-free medium, the number of colonies carrying TK derived from susceptible strains was reduced by 86%, on average, in the presence of FUdR. In contrast, the number of transformants carrying TK from resistant strains with a mutant TK were reduced by only 4%, on average, on FUdR-containing plates. We have assessed the validity of this assay with cell culture isolates and several clinical samples including two cerebrospinal fluid samples from which no virus could be isolated. This colony reduction assay allowed the correct identification of the TK phenotype of each VZV isolate tested and can be completed within 3 days of receipt of the sample.

Comparison of virus isolation and various polymerase chain reaction methods in the diagnosis of mucocutaneous herpesvirus infection

We compared two polymerase chain reaction (PCR) assays (simple and multiplex) and viral isolation to detect herpes simplex virus 1 (HSV-1) and varicella-zoster virus (VZV) in 15 clinical specimens from 13 patients with mucocutaneous herpetic infections. HSV-1 or VZV DNA was detected in 13 specimens by simple PCRs (HSV-1 or VZV PCR) and in 12 specimens by multiplex PCR. On the other hand, viral isolation was positive for 9 specimens only. The PCR protocols used in this study are not only more sensitive and faster than the traditional viral isolation and conventional PCR protocols but also can distinguish rapidly HSV-1 from VZV. We propose the PCRs described here for rapid and precise identification of etiological agents of mucocutaneous herpetic infections.

[The relationship between gene function and virulence in alpha-herpesviruses]

Virulent alpha-herpesvirus genes, though not essential for virus replication in cell culture, play important roles in virus replication in vivo. In this paper, I classify the virulent genes and discuss the relationship between gene function and virulence. The products of the virulent genes of herpes simplex virus, described in this paper, are enzymes (thymidine kinase, ribonucleotide reductase, deoxyuridine triphosphatase, DNA polymerase, and two protein kinases), glycoproteins (gC, gE), immediate early gene product (ICP47) and gamma 34.5. To identify the virulent genes of varicellazoster virus, mutation in the Oka vaccine strain was studied. The low levels of gV expression and mutation found in the immediate early gene were predicted as the cause of the attenuation of the Oka vaccine strain.

[Diagnosis of Ramsey Hunt syndrome is both simple and difficult. The viral attack is more extensive than expected earlier]

In Ramsay Hunt's syndrome (herpes zoster of the head and neck in combination with facial palsy), the vesicles often appear on the external ear (herpes zoster oticus) but they can also be found on the exterior of the neck. Serologically verified cases without vesicles occur (zoster sine herpeticum). Complications from the eighth cranial nerve (hearing loss and vertigo) are common. MR and PCR studies show a more extensive viral attack than was earlier believed to be the case. Due to the risk of remaining cranial nerve dysfunctions, as exemplified in a case report, antiviral treatment is indicated, in severe cases combined with corticosteroids. The potential value of varicella vaccination to reduce zoster complications is discussed.

High prevalence of herpes simplex virus type 2 in acute retinal necrosis syndrome associated with herpes simplex virus in Japan

PURPOSE

To determine the type of herpes simplex virus in acute retinal necrosis syndrome associated with herpes simplex virus.

METHODS

Herpes simplex virus type 1, herpes simplex virus type 2, varicella-zoster virus, Epstein-Barr virus, and cytomegalovirus were examined by polymerase chain reaction in intraocular specimens from 16 patients with acute retinal necrosis syndrome. Anti-herpes simplex virus type 1 and anti-herpes simplex virus type 2 type-specific antibodies in serum from the patients were detected by enzyme immunoassay.

RESULTS

Of 16 patients with acute retinal necrosis syndrome, seven were polymerase chain reaction positive for herpes simplex virus type 2 and nine were positive for varicella-zoster virus. Anti-herpes simplex virus type 2 antibody was positive and anti-herpes simplex virus type 1 antibody was negative in the sera of the seven patients with herpes simplex virus type 2 DNA-positive acute retinal necrosis syndrome. In contrast, anti-herpes simplex virus type 2 antibody was absent in all nine varicella-zoster virus DNA-positive acute retinal necrosis syndrome patients.

CONCLUSION

Herpes simplex virus type 2 has been demonstrated to be the major causative agent in acute retinal necrosis syndrome associated with herpes simplex virus by molecular biological and serological methods. Negative preexisting anti-herpes simplex virus type 1 antibody may play an important role in acute retinal necrosis syndrome associated with herpes simplex virus type 2.

Novel immunogenicity of Oka varicella vaccine vector expressing hepatitis B surface antigen

Recombinant Oka (ROka) varicella vaccine expressing hepatitis B surface antigen (HBsAg) and subunit HBsAg vaccine (SHV) were used as primary and booster HBsAg vaccines in 3 combinations (SHV-SHV, SHV-ROka, and ROka-SHV) in guinea pigs. Immune responses to HBsAg and varicella-zoster virus gE:gI were evaluated. The 3 combinations induced similar levels of the lymphocyte proliferation response to HBsAg. Of the 3 combinations, SHV-SHV induced the strongest antibody response to an "a" loop of HBsAg and to the whole HBsAg. Its ratio of antibody titer to this loop versus HBsAg was significantly higher than that in SHV-ROka, suggesting the supplementary recognition of the conformational epitope of HBsAg in SHV-ROka. SHV-ROka induced delayed-type hypersensitivity (DTH) to the HBsAg and gE:gI produced in infected cells. Thus, ROka induced DTH to HBsAg and enhanced recognition of the conformational epitope. ROka varicella vaccine may serve as a novel vaccine vector to induce a Th1-type immune response.

Nucleotide sequences that distinguish Oka vaccine from parental Oka and other varicella-zoster virus isolates

The sequences of approximately 34 kb from the 3' end of the varicella-zoster virus (VZV) Oka vaccine strain and the previously sequenced Dumas strain were compared. Sequence differences were noted in the coding sequences of several VZV open reading frames (ORFs), including ORFs 48, 51, 52, 55, 56, 58, 59, 60, 62, 64, and 68. Tests based on differences in the ORF62 gene and in the ORF64 poly-A region successfully distinguished the Oka vaccine strain from its wild-type parent and from other Japanese and US clinical isolates. These changes remained stable after passage of the virus in humans.

High prevalence of varicella-zoster virus reactivation in herpes simplex virus-seronegative patients with acute peripheral facial palsy

Varicella-zoster virus (VZV) and herpes simplex virus (HSV) are considered to be the major causes of acute peripheral facial palsy (APFP). One hundred and forty-two patients with APFP were analyzed by serological assays and polymerase chain reaction analysis. Ramsay Hunt syndrome was diagnosed in 21 patients. Of the remaining 121 patients clinically diagnosed with Bell's palsy, VZV reactivation without zoster (zoster sine herpete) was detected in 35 patients (29%). The prevalence of antibodies to HSV among patients with Bell's palsy was significantly higher than the prevalence among those with VZV reactivation (Ramsay Hunt syndrome or zoster sine herpete). In contrast, a high incidence (88%) of VZV reactivation among HSV-seronegative patients with APFP was observed. Our data indicate that VZV is one of the major etiologic agents of clinically diagnosed Bell's palsy and that VZV reactivation causes APFP in most patients who lack antibodies to HSV.

Nuclear accumulation of IE62, the varicella-zoster virus (VZV) major transcriptional regulatory protein, is inhibited by phosphorylation mediated by the VZV open reading frame 66 protein kinase

IE62, the major transcriptional activator protein encoded by varicella-zoster virus (VZV), locates to the nucleus when expressed in transfected cells. We show here that cytoplasmic forms of IE62 accumulate in transfected and VZV-infected cells as the result of the protein kinase activity associated with VZV open reading frame 66 (ORF66). Expression of the ORF66 protein kinase but not the VZV ORF47 protein kinase impaired the ability of coexpressed IE62 to transactivate promoter-reporter constructs. IE62 that was coexpressed with the ORF66 protein accumulated predominantly in the cytoplasm, whereas the normal nuclear localization of other proteins was not affected by the ORF66 protein. In cells infected with VZV, IE62 accumulated in the cytoplasm at late times of infection, whereas in cells infected with a VZV recombinant unable to express ORF66 protein (ROka66S), IE62 was completely nuclear. Point mutations introduced into the predicted serine/threonine catalytic domain and ATP binding domain of ORF66 abrogated its ability to influence IE62 nuclear localization, indicating that the protein kinase activity was required. The region of IE62 that was targeted by ORF66 was mapped to amino acids 602 to 733. IE62 peptides containing this region were specifically phosphorylated in cells coexpressing the ORF66 protein kinase and in cells infected with wild-type VZV but were not phosphorylated in cells infected with ROka66S. We conclude that the ORF66 protein kinase phosphorylates IE62 to induce its cytoplasmic accumulation, most likely by inhibiting IE62 nuclear import.

Viral causes of the acute retinal necrosis syndrome

PURPOSE

The primary goal of this study was to determine the viral cause of the acute retinal necrosis syndrome in 28 patients (30 eyes). A secondary goal was to investigate possible associations between viral cause and patient age, and viral cause and central nervous system disease.

METHODS

A retrospective case series in which we reviewed the laboratory results and clinical histories of 28 patients (30 eyes) diagnosed with acute retinal necrosis syndrome, from whom vitreous or aqueous specimens were received, for diagnostic evaluation using previously described polymerase chain reaction-based assays.

RESULTS

Varicella-zoster virus, herpes simplex virus, and cytomegalovirus (CMV) DNA were detected in aqueous and/or vitreous specimens from 27 of 28 patients (29 of 30 eyes with a clinical history of acute retinal necrosis syndrome). No sample was positive for DNA from more than one virus. Varicella-zoster virus DNA was detected in 13 patients (15 eyes). Median age was 57 years. Herpes simplex virus type 1 DNA was detected in seven patients (seven eyes). Median age was 47 years. Six of these patients had a history of herpes simplex virus encephalitis. Herpes simplex virus type 2 DNA was detected in six patients (six eyes). Median age was 20 years. Three of these patients had a likely history of meningitis. Cytomegalovirus DNA was detected in one patient who was immunosuppressed iatrogenically. No viral DNA was detected in one patient from whom a sample was taken after 6 weeks of acyclovir therapy.

CONCLUSIONS

The data suggest that varicella-zoster virus or herpes simplex virus type 1 cause acute retinal necrosis syndrome in patients older than 25 years, whereas herpes simplex virus type 2 causes acute retinal necrosis in patients younger than 25 years. A history of central nervous system infection in a patient with acute retinal necrosis syndrome suggests that herpes simplex virus is likely to be the viral cause.