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Context.-The ability to determine ROS1 status has become mandatory for patients with lung adenocarcinoma, as many global authorities have approved crizotinib for patients with ROS1-positive lung adenocarcinoma. Objective.-To present analytical correlation of the VENTANA ROS1 (SP384) Rabbit Monoclonal Primary Antibody (ROS1 [SP384] antibody) with ROS1 fluorescence in situ hybridization (FISH). Design.-The immunohistochemistry (IHC) and FISH analytical comparison was assessed by using 122 non-small cell lung cancer samples that had both FISH (46 positive and 76 negative cases) and IHC staining results available. In addition, reverse transcription-polymerase chain reaction (RT-PCR) as well as DNA and RNA next-generation sequencing (NGS) were used to further examine the ROS1 status in cases that were discrepant between FISH and IHC, based on staining in the cytoplasm of 2+ or above in more than 30% of total tumor cells considered as IHC positive. Here, we define the consensus status as the most frequent result across the 5 different methods (IHC, FISH, RT-PCR, RNA NGS, and DNA NGS) we used to determine ROS1 status in these cases. Results.-Of the IHC scoring methods examined, staining in the cytoplasm of 2+ or above in more than 30% of total tumor cells considered as IHC positive had the highest correlation with a FISH-positive status, reaching a positive percentage agreement of 97.8% and negative percentage agreement of 89.5%. A positive percentage agreement (100%) and negative percentage agreement (92.0%) was reached by comparing ROS1 (SP384) using a cutoff for staining in the cytoplasm of 2+ or above in more than 30% of total tumor cells to the consensus status. Conclusions.-Herein, we present a standardized staining protocol for ROS1 (SP384) and data that support the high correlation between ROS1 status and ROS1 (SP384) antibody. © 2020 College of American Pathologists. All rights reserved. Boehringer Ingelheim; Bristol-Myers Squibb; Pfizer; Novartis; Roche; AbbVie; Merck KGaA Dr Huang, Mr Smith, Dr Menzl, Dr Le, Mr Liu, Dr Ordinario, Dr Manohar, Mr Lee, Mr Rajamani, Mr Truong, Dr Jing Li, Ms Choi, Dr Jingchuan Li, Dr Pati, Dr Hanlon Newell, and Mr Pate are Roche employees and receive a salary from Roche. Dr Bubendorf received research support from Roche and received honoraria related to advisory board meetings (Pfizer, Roche). Dr Buettner is a cofounder and chief scientific officer of Targos Mol. Pathol. Inc, Kassel, Germany. Dr Kerr has received honoraria for advisory work and lectures from Ventana Medical Systems, Roche, and Pfizer; these payments were outside the scope of this work. Dr Lopez-Rios received funding and honoraria from Roche, Pfizer, and Thermo Fischer. Dr Marchetti has received honoraria for advisory work and lectures from Ventana Medical Systems, Roche, and Pfizer; these payments were outside the scope of this work. Dr Marondel is an employee and receives a salary from Pfizer. Dr Nicholson serves as a consultant and receives a fee from Merck, Boehringer Ingelheim, Pfizer (also research grant), Novartis, Astra Zeneca (also payment for lecture), Bristol-Myers Squibb, Roche, and ABBVIE. Dr Pauwels received research grants from Pfizer, Roche, and Astra Zeneca and was paid for attending advisory boards of BMS, MSD Astra Zeneca, Takedo, Roche, and Boehringer. Dr Thunnissen participates in Ventana advisory board meetings. The other authors (Dr Öz, Dr Penault-Llorca, and Dr Rossi) have no relevant financial interest in the products or companies described in this article.

Background and objective: Detection of genomic rearrangements like ALK fusions are mandatory in non-small cell lung cancer (NSCLC) as those alterations can be targeted by an increasing number of drugs. Fluorescence in-situ hybridization (FISH) is the gold standard but multiplexed technologies allow the analysis of several targets simultaneously. We have evaluated a novel RT-PCR based assay for the detection of ALK, ROS1 and RET rearrangement in NSCLC patients in this research study. Materials and Methods: FFPE tissue sections from 309 patients with late stage NSCLC were screened for ALK and ROS1 status using immunohistochemistry (IHC) and confirmed with FISH. Total nucleic acids were extracted from tissue sections using the Maxwell RSC RNA FFPE kit (Promega). Fusions were detected by RT-PCR using a prototype ALK/RET/ROS1 Fusion Panel assay (Roche). A subset of discordant cases were further analyzed by RNA sequencing using the QIAseq Targeted RNAscan Lung Cancer Panel (Qiagen). Results: All 309 samples were tested by RT-PCR with a 0% invalid rate. ALK fusions were detected in 39 samples: 29 were ALK FISH+, 5 were ALK FISH not contributive, 3 were ALK FISH- (less than 15% tumor cells presenting a gene fusion), and 2 were ALK IHC- and not tested by FISH. ROS1 fusions were detected in 12 samples: 9 were ROS1 FISH+, 1 was ROS1 FISH-, and 2 were ROS1 IHC- and not tested by FISH. RET fusions were detected in 3 samples. The remaining 255 samples were RT-PCR-: 5 were ALK FISH+ containing fusions not covered by the RT-PCR assay, 1 was ALK FISH+ containing ALK polysomy, 1 was ROS1 FISH+ containing a fusion not covered by the RT-PCR assay, 1 was ROS1 FISH+ containing ROS1 amplification, 1 was ROS1 FISH+ but ROS1 RNAseq-, and 246 samples were IHC- or IHC+/FISH-. The overall concordance rate between RT-PCR and FISH for ALK and ROS1 gene rearrangements was 91.9%. Although the RT-PCR assay did not detect 5 ALK and 1 ROS1 fusions due to design limitations, it did identify the presence of fusions in 9 tumors that were undetected by FISH (8 ALK and 1 ROS1). Conclusion: Using limited amount of biological material, RT-PCR was able to detect a substantial majority of ALK and ROS1 fusions identified by FISH, as well as fusions that were missed by the initial IHC/FISH screening. This study demonstrates RT-PCR as a feasible approach to detecting fusions in NSCLC. Citation Format: Marc G. Denis, Audrey Vallée, Christine Sagan, Guillaume Herbreteau, Sandrine Charpentier, Jaya Rajamani, Michael Lee, Ellen Ordinario. Detection of ALK, ROS1 and RET fusion transcripts in FFPE samples of non-small cell lung cancer patients using a novel RT-PCR based assay [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1271.

International audience; Background: Detection of genomic rearrangements, like anaplastic lymphoma kinase (ALK) fusions, is a pivotal requirement in non-small cell lung cancer (NSCLC) for the initiation of a targeted treatment. While tissue testing remains the gold standard, detection of these alterations using liquid biopsies is an unmet need. To enable the detection of ALK rearrangements from circulating-free RNA (cfRNA) from NSCLC patients, we have evaluated a novel reverse transcription PCR (RT-PCR) based assay.Methods: Sixty-six patients with advanced stage NSCLC were included in the study. ALK status was determined by immunohistochemistry (IHC) and/or FISH on tissue sections. For the detection of ALK rearrangements from 2ml plasma collected in EDTA or Streck BCT DNA tubes, cfRNA was extracted using a prototype cfRNA sample preparation method and tested by a novel multiplex ALK/RET RT-PCR assay (Roche).Results: Of the forty-two patients with an ALK rearrangement, 30 (71%) were included at baseline. In 10 of the baseline patients, an ALK rearrangement was detected by RT-PCR [baseline sensitivity 33.33% (95% CI: 17.29–52.81%)]. All 24 negative ALK IHC/FISH-negative patients were negative using the RT-PCR based assay (specificity =100%).Conclusions: The prototype Roche ALK/RET RT-PCR assay was able to detect ALK fusion transcripts in the plasma of NSCLC patients at baseline as well as at disease progression with limited sensitivity but high specificity. Consequently, this assay could potentially be considered to select patients for an ALK-targeting therapy when tissue samples are lacking.

The ability to determineTo present analytical correlation of the VENTANA ROS1 (SP384) Rabbit Monoclonal Primary Antibody (ROS1 [SP384] antibody) withThe immunohistochemistry (IHC) and FISH analytical comparison was assessed by using 122 non-small cell lung cancer samples that had both FISH (46 positive and 76 negative cases) and IHC staining results available. In addition, reverse transcription-polymerase chain reaction (RT-PCR) as well as DNA and RNA next-generation sequencing (NGS) were used to further examine the ROS1 status in cases that were discrepant between FISH and IHC, based on staining in the cytoplasm of 2+ or above in more than 30% of total tumor cells considered as IHC positive. Here, we define the consensus status as the most frequent result across the 5 different methods (IHC, FISH, RT-PCR, RNA NGS, and DNA NGS) we used to determine ROS1 status in these cases.Of the IHC scoring methods examined, staining in the cytoplasm of 2+ or above in more than 30% of total tumor cells considered as IHC positive had the highest correlation with a FISH-positive status, reaching a positive percentage agreement of 97.8% and negative percentage agreement of 89.5%. A positive percentage agreement (100%) and negative percentage agreement (92.0%) was reached by comparing ROS1 (SP384) using a cutoff for staining in the cytoplasm of 2+ or above in more than 30% of total tumor cells to the consensus status.Herein, we present a standardized staining protocol for ROS1 (SP384) and data that support the high correlation between ROS1 status and ROS1 (SP384) antibody.

Background and objective: Detection of genomic rearrangements like ALK fusions are of great interest in non-small cell lung cancer (NSCLC) as those alterations can be targeted by an increasing number of drugs. To overcome tissue limitations, detection of these alterations from liquid biopsies is an unmet need, despite the development of novel NGS-based tests. To allow the detection of ALK rearrangements from circulating-free RNA (cfRNA) from NSCLC patients, we have evaluated a novel RT-PCR based assay and compared the results to tissue-based testing using immunohistochemistry (IHC) or fluorescence in-situ hybridization (FISH). Materials and Methods: Sixty-five patients with late stage NSCLC were included in the study. ALK status was assessed on tissue section using immunohistochemistry and/or FISH. cfRNA was extracted from 2 ml of plasma from EDTA or Streck BCT DNA tubes using a prototype cfRNA Sample Preparation method (Roche Molecular Systems, Pleasanton, CA). For the detection of ALK-rearrangements from plasma, a prototype ALK/RET/ROS1 Fusion Panel assay (Roche) was used. Results: The analytical sensitivity of the assay was evaluated by testing plasma from healthy individuals spiked with RNA extracted from FFPE tissue section of an ALK positive tumor. Positive results were obtained with samples spiked with as little as 3 ng RNA. Of the forty-five ALK-fusion positive patients, 11 patients were already under anti-ALK therapy and in none of the patients an ALK fusion could be detected. However, of five samples tested at progression, two (40%) were tested positive. For the 29 ALK-fusion positive samples which were included at baseline prior to therapy, 11 samples have been tested positive for ALK fusions (38%). All 20 negative controls were negative using the PCR based assay. Consequently, the key test parameters for samples tested at baseline were: sensitivity = 37.93% [95% CI 20.69% - 57.74%]; specificity = 100.00% [95% 83.16% - 100.00%]; positive predictive value = 100%; negative predictive value weighted for a prevalence of ALK fusions of 4% in metastatic NSCLC patients = 97.48% [95% CI 96.68 - 98.09]. Conclusion: The prototype cobas ALK/RET/ROS1 Fusion Panel assay was able to detect ALK fusion transcripts in the plasma of NSCLC patients at baseline as well as at disease progression. Limited sensitivity could be explained by biological factors influencing nucleic acid shedding by tumours, as well as the presence of fusions not covered by the assay. However, the assay demonstrated high specificity. These data demonstrate that this assay could potentially be used to select patients for an anti-ALK therapy when tissue samples are not available. Citation Format: Simon Heeke, Marius Ilié, Maryline Allegra, Audrey Vallée, Carole Salacroup, Virginie Tanga, Véronique Hofman, Jaya Rajamani, Michael Lee, Ellen Ordinario, Marc G. Denis, Paul Hofman. Detection of ALK fusion transcripts in plasma of non-small cell lung cancer patients using a novel RT-PCR based assay [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5299.

e21695 Background: Detection of genomic rearrangements like ALK and ROS1 fusions are mandatory in non-small cell lung cancer (NSCLC) as those alterations can be targeted by an increasing number of drugs. Fluorescence in-situ hybridization (FISH) has been so far the gold standard but multiplexed technologies would allow analysis of many potential targets simultaneously. We have evaluated a novel RT-PCR based assay and a targeted RNA sequencing solution for the detection of ALK and ROS1 rearrangement in NSCLC patients. Methods: 41 patients with late stage NSCLC were included in the study. ALK and ROS1 status were screened on FFPE tissue sections using immunohistochemistry and confirmed with FISH. Total nucleic acids were extracted from tissue sections using the Maxwell RSC RNA FFPE kit (Promega). Detection of rearrangements was performed by RT-PCR using the prototype ALK/RET/ROS1 Fusion Panel assay (Roche), which detects 7 ALK fusion variants, 13 ROS1 variants and 6 RET variants. For RNA sequencing, the libraries were prepared with the QIAseq Targeted RNAscan Lung Cancer Panel (Qiagen). Sequencing was performed on a MiSeq instrument (Illumina). Results: We tested 16 ALK FISH+ tumors, 4 ROS1 FISH+ tumors, and 21 samples that were either IHC- or IHC+/FISH-. The RT-PCR assay detected 15 of the 16 ALK FISH+ tumors, and 3 of the 4 ROS1 FISH+ tumors. In the 21 IHC- or IHC+/FISH- samples, 1 additional ROS1 fusion and 1 RET fusion were detected. The remaining 19 assays samples were negative. 2 fusions were missed by RT-PCR because the assay design does not cover these rearrangements (KLC1-ALK and CTNND1-ROS1). With targeted RNA sequencing, we were able to detect 14 of the 16 ALK FISH+ tumors and all 4 of the ROS1 FISH+ tumors. We also identified 1 additional ROS1 fusion and 1 RET fusion in the 21 IHC- or IHC+/FISH- samples. 17 patients were negative and 2 tests were not contributive. Overall, using FISH as a reference, the sensitivity of both assays was 90% (18/20). Conclusions: Using limited amount of biological material, both RT-PCR and targeted RNA sequencing were able in one assay to detect the overwhelming majority of ALK and ROS1 fusions identified with FISH. These approaches also allowed us to detect gene rearrangements that were missed by the initial IHC/FISH screening. The RT-PCR assay requires less RNA (as little as 3 ng) and has a much faster turn-around time. The RNA sequencing approach allowed us to identify the fusion partners, but it requires much more RNA and is rather difficult to implement in routine practice.

The varicella-zoster virus (VZV) ORF61 protein is necessary for normal replication in vitro and virulence in human skin xenografts in the severe combined immunodeficiency mouse model in vivo . These experiments identify a hydrophobic domain that mediates ORF61 self-interaction. While not needed to inhibit host cell defenses, disruption of this domain (residues 250 to 320) severely impairs VZV growth, transactivation of the immediate early 63 and glycoprotein E genes, and the pathogenesis of VZV skin infection in vivo .

Varicella-zoster virus (VZV) is a human α-herpesvirus that causes varicella (chickenpox) during primary infection and zoster (shingles) upon reactivation. Like other viruses, VZV must subvert the intrinsic antiviral defenses of differentiated human cells to produce progeny virions. Accordingly, VZV inhibits the activation of the cellular transcription factors IFN regulatory factor 3 (IRF3) and signal transducers and activators of transcription 1 (STAT1), thereby downregulating antiviral factors, including IFNs. Conversely, in this study, we found that VZV triggers STAT3 phosphorylation in cells infected in vitro and in human skin xenografts in SCID mice in vivo and that STAT3 activation induces the anti-apoptotic protein survivin. Small-molecule inhibitors of STAT3 phosphorylation and survivin restrict VZV replication in vitro, and VZV infection of skin xenografts in vivo is markedly impaired by the administration of the phospho-STAT3 inhibitor S3I-201. STAT3 and survivin are required for malignant transformation caused by γ-herpesviruses, such as Kaposi's sarcoma virus. We show that STAT3 activation is also critical for VZV, a nononcogenic herpesvirus, via a survivin-dependent mechanism. Furthermore, STAT3 activation is critical for the life cycle of the virus because VZV skin infection is necessary for viral transmission and persistence in the human population. Therefore, we conclude that takeover of this major cell-signaling pathway is necessary, independent of cell transformation, for herpesvirus pathogenesis and that STAT3 activation and up-regulation of survivin is a common mechanism important for the pathogenesis of lytic as well as tumorigenic herpesviruses.

Varicella-zoster virus (VZV) is the alphaherpesvirus that causes chicken pox (varicella) and shingles (zoster). The two VZV glycoproteins gE and gI form a heterodimer that mediates efficient cell-to-cell spread. Deletion of gI yields a small-plaque-phenotype virus, ΔgI virus, which is avirulent in human skin using the xenograft model of VZV pathogenesis. In the present study, 10 mutant viruses were generated to determine which residues were required for the typical function of gI. Three phosphorylation sites in the cytoplasmic domain of gI were not required for VZV virulence in vivo . Two deletion mutants mapped a gE binding region in gI to residues 105 to 125. A glycosylation site, N116, in this region did not affect virulence. Substitution of four cysteine residues highly conserved in the Alphaherpesvirinae established that C95 is required for gE/gI heterodimer formation. The C95A and Δ105–125 (with residues 105 to 125 deleted) viruses had small-plaque phenotypes with reduced replication kinetics in vitro similar to those of the ΔgI virus. The Δ105–125 virus was avirulent for human skin in vivo . In contrast, the C95A mutant replicated in vivo but with significantly reduced kinetics compared to those of the wild-type virus. In addition to abolished gE/gI heterodimer formation, gI from the C95A or the Δ105–125 mutant was not recognized by monoclonal antibodies that detect the canonical conformation of gI, demonstrating structural disruption of gI in these viruses. This alteration prevented gI incorporation into virus particles. Thus, residues C95 and 105 to 125 are critical for gI structure required for gE/gI heterodimer formation, virion incorporation, and ultimately, effective viral spread in human skin.

MxA is an antiviral protein induced by interferon (IFN)-α/β that is known to inhibit the replication of many RNA viruses. In these experiments, the 76-kDa MxA protein expressed in IFN-α-treated cells was shown to have antiviral activity against herpes simplex virus-1 (HSV-1), a human DNA virus. However, MxA was expressed as a 56-kDa protein in HSV-1-infected cells in the absence of IFN-α. This previously unrecognized MxA isoform was produced from an alternatively spliced MxA transcript that had a deletion of Exons 14–16 and a frame shift altering the C-terminus. The variant MxA (varMxA) isoform was associated with HSV-1 regulatory proteins and virions in nuclear replication compartments. varMxA expression enhanced HSV-1 infection as shown by a reduction in infectious virus titers from cells in which MxA had been inhibited by RNA interference and by an increase in HSV-1 titers when the 56-kDa varMxA was expressed constitutively. Thus, the human MxA gene encodes two MxA isoforms, which are expressed differentially depending on whether the stimulus is IFN-α or HSV-1. These findings show that alternative splicing of cellular mRNA can result in expression of a novel isoform of a host defense gene that supports instead of restricting viral infection.

Varicella-zoster virus (VZV) causes varicella and establishes latency in sensory nerve ganglia, but the characteristics of VZV latency are not well defined. Immunohistochemical detection of the VZV immediate-early 63 (IE63) protein in ganglion neurons has been described, but there are significant discrepancies in estimates of the frequency of IE63-positive neurons, varying from a rare event to abundant expression. We examined IE63 expression in cadaver ganglia using a high-potency rabbit anti-IE63 antibody and corresponding preimmune serum. Using standard immunohistochemical techniques, we evaluated 10 ganglia that contained VZV DNA from seven individuals. These experiments showed that neuronal pigments were a confounding variable; however, by examining sections coded to prevent investigator bias and applying statistical analysis, we determined that IE63 protein, if present, is in a very small proportion of neurons (

Varicella-zoster virus (VZV) open reading frame 61 (ORF61) encodes a protein that transactivates viral and cellular promoters in transient-transfection assays and is the ortholog of herpes simplex virus ICP0. In this report, we mapped the ORF61 promoter and investigated its regulation by viral and cellular proteins in transient-expression experiments and by mutagenesis of the VZV genome (parent Oka strain). The 5′ boundary of the minimal ORF61 promoter required for IE62 transactivation was mapped to position −95 relative to the mRNA start site, and three noncanonical GT-rich Sp1-binding sites were documented to occur within the region comprising positions −95 to −45. Contributions of the three Sp1-binding-site motifs, designated Sp1a, Sp1b, and Sp1c, to ORF61 expression and viral replication were varied despite their similar sequences. Two sites, Sp1a and Sp1c, functioned synergistically. When both sites were mutated in the pOka genome to produce pOka-61proΔSp1ac, the mutant virus expressed significantly less ORF61 protein. Using this mutant to investigate ORF61 functions resulted in reductions in the expression levels of IE proteins, viral kinases ORF47 and ORF66, and the major glycoprotein gE, with the most impact on gE. Virion morphogenesis appeared to be intact despite minimal ORF61 expression. Pretreating melanoma cells with sodium butyrate enhanced titers of pOka-61proΔSp1ac but not pOka, suggesting that ORF61 has a role in histone deacetylase inhibition. Growth of pOka-61proΔSp1ac was impaired in SCIDhu skin xenografts, indicating that the regulation of the ORF61 promoter by Sp1 family proteins is important for ORF61 expression in vivo and that ORF61 contributes to VZV virulence at skin sites of replication.

Varicella-zoster virus (VZV) glycoprotein E (gE) is the most abundant glycoprotein in infected cells and, in contrast to those of other alphaherpesviruses, is essential for viral replication. The gE ectodomain contains a unique N-terminal region required for viral replication, cell-cell spread, and secondary envelopment; this region also binds to the insulin-degrading enzyme (IDE), a proposed VZV receptor. To identify new functional domains of the gE ectodomain, the effect of mutagenesis of the first cysteine-rich region of the gE ectodomain (amino acids 208 to 236) was assessed using VZV cosmids. Deletion of this region was compatible with VZV replication in vitro, but cell-cell spread of the rOka-ΔCys mutant was reduced significantly. Deletion of the cysteine-rich region abolished the binding of the mutant gE to gI but not to IDE. Preventing gE binding to gI altered the pattern of gE expression at the plasma membrane of infected cells and the posttranslational maturation of gI and its incorporation into viral particles. In contrast, deletion of the first cysteine-rich region did not affect viral entry into human tonsil T cells in vitro or into melanoma cells infected with cell-free VZV. These experiments demonstrate that gE/gI heterodimer formation is essential for efficient cell-cell spread and incorporation of gI into viral particles but that it is dispensable for infectious varicella-zoster virion formation and entry into target cells. Blocking gE binding to gI resulted in severe impairment of VZV infection of human skin xenografts in SCIDhu mice in vivo, documenting the importance of cell fusion mediated by this complex for VZV virulence in skin.

Varicella-zoster virus (VZV) is a host specific human pathogen that has been studied using human xenografts in SCID mice. Live whole-animal imaging is an emerging technique to measure protein expression in vivo using luminescence. Currently, it has only been possible to determine VZV protein expression in xenografts postmortem. Therefore, to measure immediate early (IE63) and late (glycoprotein E [gE]) protein expression in vivo viruses expressing IE63 or gE as luciferase fusion proteins were generated. Viable recombinant viruses pOka-63-luciferase and pOka-63/70-luciferase, which had luciferase genes fused to ORF63 and its duplicate ORF70, or pOka-gE-CBR were recovered that expressed IE63 or gE as fusion proteins and generated luminescent plaques. In contrast to pOka-63/70-luciferase viruses, the luciferase gene was rapidly lost in vitro when fused to a single copy of ORF63 or ORF68. IE63 expression was successfully measured in human skin and dorsal root ganglia xenografts infected with the genomically stable pOka-63/70-luciferase viruses. The progress of VZV infection in dorsal root ganglia xenografts was delayed in valacyclovir treated mice but followed a similar trend in untreated mice when the antiviral was withdrawn 28 days post-inoculation. Thus, IE63-luciferase fusion proteins were effective for investigating VZV infection and antiviral activity in human xenografts.

The assembly of herpesvirus capsids is a complex process involving interactions of multiple proteins in the cytoplasm and in the nucleus. Based on comparative genome analyses, varicella-zoster virus (VZV) open reading frame 23 (ORF23) encodes a conserved capsid protein, referred to as VP26 (UL35) in other alphaherpesviruses. Mutagenesis using a VZV bacterial artificial chromosome system showed that ORF23 was dispensable for replication in vitro. However, the absence of ORF23 disrupted capsid assembly in a melanoma cell line. Expression of ORF23 as a red fluorescent protein (RFP) fusion protein appeared to have a dominant negative effect on replication that was rescued by ORF23 expression from a nonnative site in the VZV genome. In contrast to its VP26 homolog, ORF23 has an intrinsic nuclear localization capacity that was mapped to an SRSRVV motif at residues 229 to 234 in the extreme C terminus of ORF23. In addition, coexpression with ORF23 resulted in nuclear import of the major capsid protein, ORF40. VZV ORF33.5 also translocated ORF40, which may provide a redundant mechanism in vitro but appears insufficient to overcome the dominant negative effect of the monomeric RFP-ORF23 (mRFP23) fusion protein. ORF23 was required for VZV infection of human skin xenografts, indicating that ORF33.5 does not compensate for lack of ORF23 in vivo. These observations suggest a model of VZV capsid assembly in which nuclear transport of the major capsid protein and associated proteins requires ORF23 during VZV replication in the human host. If so, ORF23 expression could be a target for a novel antiviral drug against VZV.

Varicella-zoster virus (VZV) glycoprotein E (gE) is essential for viral replication and is involved in cell-to-cell spread, secondary envelopment, and entry. We created a set of mutations in the gE promoter to investigate the role of viral and cellular transcriptional factors in regulation of the gE promoter. Deletion or point mutation of the two Sp1 sites in the gE promoter abolished Sp1 binding and IE62-mediated transactivation of the gE promoter in vitro. Incorporation of the deletion or the point mutations disrupting both of the Sp1 binding sites into the VZV genome was not compatible with viral replication. A point mutation altering the atypical Sp1 binding site was lethal, while altering the second site impaired VZV replication significantly, indicating functional differences between the two Sp1 binding sites. Deletions in the gE promoter that abolished putative binding sites for cellular transcriptional factors other than Sp1, identified by bioinformatics analysis, were inserted in the VZV genome. Replication of the viruses with mutations of the gE promoter did not differ from control recombinants in melanoma cells or primary human tonsil T cells in vitro. These deletions did not affect infection of human skin xenografts in SCIDhu mice. These results indicate that Sp1 is required for IE62-mediated transactivation of the gE promoter and that this transcriptional factor appears to be the only cellular factor essential for regulation of the gE promoter.

Expansion of GAA repeats in the intron of the frataxin gene is involved in the autosomal recessive Friedreich's ataxia (FRDA). The GAA repeats arise from a stretch of adenine residues of an Alu element. These repeats have a size ranging from 7- 38 in the normal population, and expand to thousands in the affected individuals. The mechanism of origin of GAA repeats, their polymorphism and stability are not well understood. In this study, we have carried out an extensive analysis of GAA repeats at several loci in the humans. This analysis indicates the association of a majority of GAA repeats with the 3' end of an "A" stretch present in the Alu repeats. Further, the prevalence of GAA repeats correlates with the evolutionary age of Alu subfamilies as well as with their relative frequency in the genome. Our study on GAA repeat polymorphism at some loci in the normal population reveals that the length of the GAA repeats is determined by the relative length of the flanking A stretch. Based on these observations, a possible mechanism for origin of GAA repeats and modulatory effects of flanking sequences on repeat instability mediated by DNA triplex is proposed.

Enveloped viruses require membrane fusion for cell entry and replication. For herpesviruses, this event is governed by the multiprotein core complex of conserved glycoproteins (g)B and gH/gL. The recent crystal structures of gH/gL from herpes simplex virus 2, pseudorabies virus, and Epstein–Barr virus revealed distinct domains that, surprisingly, do not resemble known viral fusogens. Varicella-zoster virus (VZV) causes chicken pox and shingles. VZV is an α-herpesvirus closely related to herpes simplex virus 2, enabling prediction of the VZV gH structure by homology modeling. We have defined specific roles for each gH domain in VZV replication and pathogenesis using structure-based site-directed mutagenesis of gH. The distal tip of domain (D)I was important for skin tropism, entry, and fusion. DII helices and a conserved disulfide bond were essential for gH structure and VZV replication. An essential 724 CXXC 727 motif was critical for DIII structural stability and membrane fusion. This assignment of domain-dependent mechanisms to VZV gH links elements of the glycoprotein structure to function in herpesvirus replication and virulence.

Varicella-zoster virus (VZV) is a neurotropic alphaherpesvirus. VZV infection of human dorsal root ganglion (DRG) xenografts in immunodeficient mice models the infection of sensory ganglia. We examined DRG infection with recombinant VZV (recombinant Oka [rOka]) and the following gE mutants: gEΔ27-90, gEΔCys, gE-AYRV, and gE-SSTT. gEΔ27-90, which lacks the gE domain that interacts with a putative receptor insulin-degrading enzyme (IDE), replicated as extensively as rOka, producing infectious virions and significant cytopathic effects within 14 days of inoculation. Since neural cells express IDE, the gE/IDE interaction was dispensable for VZV neurotropism. In contrast, gEΔCys, which lacks gE/gI heterodimer formation, was significantly impaired at early times postinfection; viral genome copy numbers increased slowly, and infectious virus production was not detected until day 28. Delayed replication was associated with impaired cell-cell spread in ganglia, similar to the phenotype of a gI deletion mutant (rOkaΔgI). However, at later time points, infection of satellite cells and other supportive nonneuronal cells resulted in extensive DRG tissue damage and cell loss such that cytopathic changes observed at day 70 were more severe than those for rOka-infected DRG. The replication of gE-AYRV, which is impaired for trans -Golgi network (TGN) localization, and the replication of gE-SSTT, which contains mutations in an acidic cluster, were equivalent to that of rOka, causing significant cytopathic effects and infectious virus production by day 14; genome copy numbers were equivalent to those of rOka. These experiments suggest that the gE interaction with cellular IDE, gE targeting to TGN sites of virion envelopment, and phosphorylation at SSTT are dispensable for VZV DRG infection, whereas the gE/gI interaction is critical for VZV neurovirulence.

Varicella-zoster virus (VZV) is an alphaherpesvirus that infects skin, lymphocytes, and sensory ganglia. VZV glycoprotein E (gE) has a unique N-terminal region (aa1-188), which is required for replication and includes domains involved in secondary envelopment, efficient cell-cell spread, and skin infection in vivo. The nonconserved N-terminal region also mediates binding to the insulin-degrading enzyme (IDE), which is proposed to be a VZV receptor. Using viral mutagenesis to make the recombinant rOka-ΔP27-G90, we showed that amino acids in this region are required for gE/IDE binding in infected cells; this deletion reduced cell-cell spread in vitro and skin infection in vivo. However, a gE point mutation, linker insertions, and partial deletions in the aa27-90 region, and deletion of a large portion of the unique N-terminal region, aa52-187, had similar or more severe effects on VZV replication in vitro and in vivo without disrupting the gE/IDE interaction. VZV replication in T cells in vivo was not impaired by deletion of gE aa27-90, suggesting that these gE residues are not essential for VZV T cell tropism. However, the rOka-ΔY51-P187 mutant failed to replicate in T cell xenografts as well as skin in vivo. VZV tropism for T cells and skin, which is necessary for its life cycle in the human host, requires this nonconserved region of the N-terminal region of VZV gE.

Glycoprotein B (gB), the most conserved protein in the family Herpesviridae , is essential for the fusion of viral and cellular membranes. Information about varicella-zoster virus (VZV) gB is limited, but homology modeling showed that the structure of VZV gB was similar to that of herpes simplex virus (HSV) gB, including the putative fusion loops. In contrast to HSV gB, VZV gB had a furin recognition motif ([R]-X-[KR]-R-|-X, where | indicates the position at which the polypeptide is cleaved) at residues 491 to 494, thought to be required for gB cleavage into two polypeptides. To investigate their contribution, the putative primary fusion loop or the furin recognition motif was mutated in expression constructs and in the context of the VZV genome. Substitutions in the primary loop, W180G and Y185G, plus the deletion mutation Δ 491 RSRR 494 and point mutation 491 GSGG 494 in the furin recognition motif did not affect gB expression or cellular localization in transfected cells. Infectious VZV was recovered from parental Oka (pOka)-bacterial artificial chromosomes that had either the Δ 491 RSRR 494 or 491 GSGG 494 mutation but not the point mutations W180G and Y185G, demonstrating that residues in the primary loop of gB were essential but gB cleavage was not required for VZV replication in vitro. Virion morphology, protein localization, plaque size, and replication were unaffected for the pOka-gBΔ 491 RSRR 494 or pOka-gB 491 GSGG 494 virus compared to pOka in vitro. However, deletion of the furin recognition motif caused attenuation of VZV replication in human skin xenografts in vivo. This is the first evidence that cleavage of a herpesvirus fusion protein contributes to viral pathogenesis in vivo, as seen for fusion proteins in other virus families.

Promyelocytic leukemia protein (PML) has antiviral functions and many viruses encode gene products that disrupt PML nuclear bodies (PML NBs). However, evidence of the relevance of PML NB modification for viral pathogenesis is limited and little is known about viral gene functions required for PML NB disruption in infected cells in vivo. Varicella-zoster virus (VZV) is a human alphaherpesvirus that causes cutaneous lesions during primary and recurrent infection. Here we show that VZV disrupts PML NBs in infected cells in human skin xenografts in SCID mice and that the disruption is achieved by open reading frame 61 (ORF61) protein via its SUMO-interacting motifs (SIMs). Three conserved SIMs mediated ORF61 binding to SUMO1 and were required for ORF61 association with and disruption of PML NBs. Mutation of the ORF61 SIMs in the VZV genome showed that these motifs were necessary for PML NB dispersal in VZV-infected cells in vitro. In vivo, PML NBs were highly abundant, especially in basal layer cells of uninfected skin, whereas their frequency was significantly decreased in VZV-infected cells. In contrast, mutation of the ORF61 SIMs reduced ORF61 association with PML NBs, most PML NBs remained intact and importantly, viral replication in skin was severely impaired. The ORF61 SIM mutant virus failed to cause the typical VZV lesions that penetrate across the basement membrane into the dermis and viral spread in the epidermis was limited. These experiments indicate that VZV pathogenesis in skin depends upon the ORF61-mediated disruption of PML NBs and that the ORF61 SUMO-binding function is necessary for this effect. More broadly, our study elucidates the importance of PML NBs for the innate control of a viral pathogen during infection of differentiated cells within their tissue microenvironment in vivo and the requirement for a viral protein with SUMO-binding capacity to counteract this intrinsic barrier., Author Summary PML nuclear bodies (PML NBs) are spherical nuclear structures that are present in most human and animal cells. These bodies contribute to anti-viral defense and therefore many viruses have developed strategies to disrupt them. This interaction has been demonstrated for a number of viruses in cultured cells but little is known about these processes in differentiated cells within human tissues. Varicella-zoster virus (VZV) is a human alphaherpesvirus that causes chicken pox and shingle lesions in skin. Here we show that VZV disrupts PML NBs in epidermal and dermal cells in skin tissues implanted subcutaneously in immunodeficient mice. We found that PML NB dispersal is mediated by VZV ORF61 protein and is required for VZV cell to cell spread and lesion formation in skin. The ability of ORF61 to disrupt PML NBs depends on its capacity to bind to SUMO1 protein, which is conjugated to PML and other proteins within PML NBs. To our knowledge, our study provides the first evidence of PML NB modification through the SUMO-binding function of a viral protein, VZV ORF61, and the importance of this molecular mechanism for virus-induced PML NB disruption in differentiated cells infected within their tissue microenvironment in vivo.

The deletion of ORF11 severely impaired VZV infection of human skin xenografts. Here, we investigate the characteristics and functions of the ORF11 gene product. ORF11 is expressed as a 118kDa polypeptide in VZV-infected cells; the protein is present in the nucleus and cytoplasm and is incorporated into VZ virions. Although ORF11 had little effect in transactivating VZV gene promoters in transfection assays, deleting ORF11 from the virus was associated with reduced expression of immediate early proteins IE4, IE62 and IE63, and the major glycoprotein, gE. ORF11 was identified as an RNA binding protein and its RNA binding domain was defined. However, disrupting the ORF11 RNA binding domain did not affect skin infection, indicating that RNA binding capacity, conserved among the alphahepesviruses homologues, is not essential while the contribution of ORF11 to the expression of the IE proteins and gE may be required for VZV pathogenesis in skin in vivo.