[THE IMPACT OF MOLECULAR PROFILING USING NEXT-GENERATION SEQUENCING IN ADVANCED LUNG CANCER].

BACKGROUND: In the last decade, important advances in understanding the lung cancer cellular signal pathways have led to the designing of targeted drugs that significantly prolong survival. Recent data shows that 64% of lung adenocarcinomas harbor at least one activating driver mutation, including treatable mutations such as RET, ERBB2 (HER-2) and ROS1 gene mutations, besides the regularly screened ALK and EGFR genes. Next-Generation Sequencing (NGS) reveals more clinically meaningful genomic alterations as compared to currently used diagnostic tests. However, the clinical impact of NGS testing merits further investigation. OBJECTIVES: To evaluate the impact of NGS-based tumor profiling on therapeutic decision making in the real life setting in advanced lung cancer patients. METHODS: The study population included 50 lung cancer patients who were treated at Davidoff Cancer Center, Rabin Medical Center in 2011-2015, and for whom a broad, hybrid capture-based NGS genomic profiling test was performed. The data was retrospectively collected from patient charts. RESULTS: 39 of 46 included patients (84.8%) had one or more driver alternations, and a targeted agent was administered according to alteration discovered in 21 of 46 cases (45.7%). 15 (37.5%) treated patients were exclusively detected by NGS. The most frequent drivers were EGFR (26.1%), KRAS (19.6%), ALK (13%), STK11 (10.9%) and RET (8.7%). Interestingly, 10 patients became EGFR and ALK positive by NGS after the previous standard local molecular testing was negative. CONCLUSIONS: Molecular testing using NGS can reveal a targetable genomic alteration in the vast majority of lung tumors. Its broad use for therapeutic decision making is essential since approximately half of the patients can benefit from customized treatment upon testing results. DISCUSSION: Although this topic needs to be further assessed in large randomized controlled trials, our positive results emphasize the importance of multiplex testing as a diagnostic test in advanced lung cancer patients. The implementation of NGS at Rabin Medical Center in the near future is highly anticipated.

Fluorescence in situ hybridization, immunohistochemistry, and next-generation sequencing for detection of EML4-ALK rearrangement in lung cancer.

BACKGROUND: The U.S. Food and Drug Administration-approved method for detecting EML4-ALK rearrangement is fluorescence in situ hybridization (FISH); however, data supporting the use of immunohistochemistry (IHC) for that purpose are accumulating. Previous studies that compared FISH and IHC considered FISH the gold standard, but none compared data with the results of next-generation sequencing (NGS) analysis. MATERIALS AND METHODS: We studied FISH and IHC (D5F3 antibody) systematically for EML4-ALK rearrangement in 51 lung adenocarcinoma patients, followed by NGS in case of discordance. RESULTS: Of 51 patients, 4 were positive with FISH (7.8%), and 8 were positive with IHC (15.7%). Three were positive with both. NGS confirmed that four of the five patients who were positive with IHC and negative with FISH were positive for ALK. Two were treated by crizotinib, with progression-free survival of 18 and 6 months. Considering NGS as the most accurate test, the sensitivity and specificity were 42.9% and 97.7%, respectively, for FISH and 100% and 97.7%, respectively, for IHC. CONCLUSION: The FISH-based method of detecting EML4-ALK rearrangement in lung cancer may miss a significant number of patients who could benefit from targeted ALK therapy. Screening for EML4-ALK rearrangement by IHC should be strongly considered, and NGS is recommended in borderline cases. Two patients who were negative with FISH and positive with IHC were treated with crizotinib and responded to therapy.

Volatile fingerprints of cancer specific genetic mutations.

We report on a new concept for profiling genetic mutations of (lung) cancer cells, based on the detection of patterns of volatile organic compounds (VOCs) emitted from cell membranes, using an array of nanomaterial-based sensors. In this in-vitro pilot study we have derived a volatile fingerprint assay for representative genetic mutations in cancer cells that are known to be associated with targeted cancer therapy. Five VOCs were associated with the studied oncogenes, using complementary chemical analysis, and were discussed in terms of possible metabolic pathways. The reported approach could lead to the development of novel methods for guiding treatments, so that patients could benefit from safer, more timely and effective interventions that improve survival and quality of life while avoiding unnecessary invasive procedures. Studying clinical samples (tissue/blood/breath) will be required as next step in order to determine whether this cell-line study can be translated into a clinically useful tool. FROM THE CLINICAL EDITOR: In this novel study, a new concept for profiling genetic mutations of (lung) cancer cells is described, based on the detection of patterns of volatile organic compounds emitted from cell membranes, using an array of nano-gold based sensors.

Characterization of a novel virus causing a lethal disease in carp and koi.

Since 1998 a lethal disease of carp and ornamental koi (Cyprinus carpio) has afflicted fisheries in North America, Europe, and Asia, causing severe economic losses to the fish farming industry. This review summarizes the isolation and identification of the disease-causing agent and describes the currently known molecular characteristics of this newly isolated virus, distinguishing it from other known large DNA viruses. In addition, we summarize the clinical and histopathological manifestations of the disease. Providing information on the immune response to this virus and evaluating the available means of diagnosis and protection should help to reduce the damage induced by this disease. This review does not discuss the economic aspects of the disease or the debate on whether the disease should be registered; both of these issues were recently reviewed in detail (O. L. M. Haenen, K. Way, S. M. Bergmann, and E. Ariel, Bull. Eur. Assoc. Fish Pathol. 24:293-307, 2004; D. Pokorova, T. Vesely, V. Piackova, S. Reschova, and J. Hulova, Vet. Med. Czech. 50:139-147, 2005).

Rare targetable drivers (RTDs) in non-small cell lung cancer (NSCLC): Outcomes with immune check-point inhibitors (ICPi).

OBJECTIVES: Efficacy of immune check-point inhibitors (ICPi) in NSCLC with rare targetable drivers (RTDs) is largely unknown. MATERIALS AND METHODS: Consecutive patients with NSCLC and RTDs (non-EGFR/ALK, n-82) were selected from the Davidoff Cancer Center database. ORR, PFS, OS with ICPi, OS since advanced disease diagnosis, TMB, MSI, and PD-L1 expression were analyzed; uni- and multivariate PFS and OS analyses were done. OS with ICPi was compared between the RTD cohort and the non-selected NSCLC cohort (n-278). RESULTS: Of 50 tumors tested, 32%, 38%, and 30% were associated with ≥50%, 1-49% and <1% PD-L1 expression, respectively. Median TMB (n-48) comprised 4 muts/Mb (0-57); TMB ≥ 10 muts/Mb was seen in 19% of tumors. Both TMB and PD-L1 expression varied across different RTDs. All the 47 tumors were MSI stable. ORR with ICPi (n-44) was 16%, median PFS was 3.2 months (95% CI, 2.6-5.0), median OS was 16.2 months (95% CI, 8.4-NR). No correlation was seen between OS with ICPi and PD-L1 expression (p > 0.4), TMB (p > 0.8), or RTD type (p > 0.3). In the multivariate analysis, ECOG PS (p-0.005), targeted agents exposure (p-0.005), and ICPi exposure (p-0.04) were the only variables which correlated with OS since advanced disease diagnosis. Median OS since advanced disease diagnosis comprised 32 months (95% CI, 19.9-44.9) and 13 months (95% CI, 6.6-15.9) for patients who were and were not exposed to ICPi, respectively (log-rank test-6.3; p-0.01). In the inter-cohort comparison, for patients matched for ECOG PS (0/1), median OS with ICPi comprised 17.5 months (95% CI, 8.1-NR) and 8.6 months (95% CI, 6.7-NR) for RTD and non-selected patients, respectively (log-rank test-2.4, p-0.1). CONCLUSION: In NSCLC with RTD, ICPi have favorable efficacy and independent impact on OS. NSCLC with RTD is associated with MSI stable status and variable levels of PD-L1 expression and TMB; their predictive value remains to be determined.

The Clinical Impact of Comprehensive Genomic Testing of Circulating Cell-Free DNA in Advanced Lung Cancer.

INTRODUCTION: Next-generation sequencing (NGS) of cell-free circulating tumor DNA (cfDNA) enables noninvasive genomic analysis of NSCLC patients. Although plasma-detected genomic alterations (GAs) have been shown to predict targeted therapy response, evidence of durability of response is lacking or limited to small cohorts as is the impact of cfDNA NGS results on clinical decisions. METHODS: This retrospective study of stage IIIB/IV NSCLC patients between the years 2014 and 2017 in Israel used cfDNA NGS (Guardant360; Guardant Health, Inc., Redwood City, California) to identify targetable GAs. RESULTS: We consecutively tested 116 NSCLC patients, 41.4% before first-line therapy (group A), 34.5% upon progression on chemotherapy or immunotherapy (group B1), and 24.1% upon progression on EGFR tyrosine kinase inhibitors (group B2). Targetable GAs were found in 31% of group A (15 of 48 patients), 32.5% in group B1 (13 of 40 patients) and 71% in group B2 (20 of 28 patients). Treatment decision was changed to targeted therapy in 23% (11 of 48 patients), 25% (10 of 40 patients) and 32% (9 of 28 patients), respectively (total cohort 26%; 30/116). Objective response rate (Response Evaluation Criteria in Solid Tumors) was 43% (12 of 28 patients) including one complete response, partial response in 39% (11 of 28 patients), stable disease in 32% (9 of 28 patients), and progressive disease in 25% (7 of 28 patients). Disease control rate was 75% for 5 months median treatment duration. CONCLUSIONS: Comprehensive cfDNA testing impacted clinical decisions in one-quarter to one-third of initial and subsequent lines of treatment in advanced NSCLC patients. This retrospective study extends previous reports by showing that responses based on cfDNA are durable and change treatment decisions at initial presentation and at progression.

Clinical Impact of Hybrid Capture-Based Next-Generation Sequencing on Changes in Treatment Decisions in Lung Cancer.

INTRODUCTION: Targeted therapy significantly prolongs survival in lung adenocarcinoma. Current diagnostic guidelines include only EGFR and anaplastic lymphoma receptor tyrosine kinase gene (ALK) testing. Next-generation sequencing (NGS) reveals more actionable genomic alterations than do standard diagnostic methods. Data on the influence of hybrid capture (HC)-based NGS on treatment are limited, and we investigated its impact on treatment decisions and clinical outcomes. METHODS: This retrospective study included patients with advanced lung cancer on whom HC-based NGS was performed between November 2011 and October 2015. Demographic and clinicopathologic characteristics, treatments, and outcome data were collected. RESULTS: A total of 101 patients were included (median age 63 years [53% females, 45% never-smokers, and 85% with adenocarcinoma]). HC-based NGS was performed upfront and after EGFR/ALK testing yielded negative or inconclusive results in 15% and 85% of patients, respectively. In 51.5% of patients, HC-based NGS was performed before first-line therapy, and in 48.5%, it was performed after treatment failure. HC-based NGS identified clinically actionable genomic alterations in 50% of patients, most frequently in EGFR (18%), Ret proto-oncogene (RET) (9%), ALK (8%), Mesenchymal-epithelial transition factor (MET) receptor tyrosine kinase gene (6%), and erb-b2 receptor tyrosine kinase 2 gene (ERBB2) (5%). In 15 patients, it identified EGFR/ALK aberrations after negative results of prior standard testing. Treatment strategy was changed for 43 patients (42.6%). The overall response rate in these patients was 65% (complete response 14.7%, partial response 50%). Median survival was not reached. Immunotherapy was administered in 33 patients, mostly without an actionable driver, with a presenting disease control rate of 32%, and with an association with tumor mutation burden. CONCLUSIONS: HC-based NGS influenced treatment decisions in close to half of the patients with lung adenocarcinoma and was associated with an overall response rate of 65%, which may translate into a survival benefit.

Detection of Lung Cancer and EGFR Mutation by Electronic Nose System.

INTRODUCTION: Early detection of lung cancer (LC) has been well established as a significant key point in patient survival and prognosis. New highly sensitive nanoarray sensors for exhaled volatile organic compounds that have been developed and coupled with powerful statistical programs may be used when diseases such as LC are suspected. Detection of genetic aberration mutation by nanoarray sensors is the next target. METHODS: Breath samples were taken from patients who were evaluated for suspicious pulmonary lesions. Patients were classified as those with benign nodules, as patients with LC with or without the EGFR mutation, and according to their smoking status. Breath prints were recognized by nanomaterial-based sensor array, and pattern recognition methods were used. RESULTS: A total of 119 patients participated in this study, 30 patients with benign nodules and 89 patients with LC (16 with early disease and 73 with advanced disease). Patients with LC who harbored the EGFR mutation (n = 19) could be discriminated from those with wild-type EGFR (n = 34) with an accuracy of 83%, sensitivity of 79%, and specificity of 85%. Discrimination of early LC from benign nodules had 87% accuracy and positive and negative predictive values of 87.7 and 87.5% respectively. Moderate discrimination (accuracy of 76%) was found between LC of heavy smokers and that of never-smokers or distant past light smokers. CONCLUSIONS: Breath analysis could discriminate patients with LC who harbor the EGFR mutation from those with wild-type EGFR and those with benign pulmonary nodules from those patients with early LC. A positive breath print for the EGFR mutation may be used in treatment decisions if tissue sampling does not provide adequate material for definitive mutation analysis.

Cancer metabolism: the volatile signature of glycolysis-in vitro model in lung cancer cells.

Discovering the volatile signature of cancer cells is an emerging approach in cancer research, as it may contribute to a fast and simple diagnosis of tumors in vivo and in vitro. One of the main contributors to such a volatile signature is hyperglycolysis, which characterizes the cancerous cell. The metabolic perturbation in cancer cells is known as the Warburg effect; glycolysis is preferred over oxidative phosphorylation (OXPHOS), even in the presence of oxygen. The precise mitochondrial alterations that underlie the increased dependence of cancer cells on aerobic glycolysis for energy generation have remained a mystery. We aimed to profile the volatile signature of the glycolysis activity in lung cancer cells. For that an in vitro model, using lung cancer cell line cultures (A549, H2030, H358, H322), was developed. The volatile signature was measured by proton transfer reaction mass spectrometry under normal conditions and glycolysis inhibition. Glycolysis inhibition and mitochondrial activity were also assessed by mitochondrial respiration capacity measurements. Cells were divided into two groups upon their glycolytic profile (PET positive and PET negative). Glycolysis blockade had a unique characteristic that was shared by all cells. Furthermore, each group had a characteristic volatile signature that enabled us to discriminate between those sub-groups of cells. In conclusion, lung cancer cells may have different subpopulations of cells upon low and high mitochondrial capacity. In both groups, glycolysis blockade induced a unique volatile signature.

RET Fusion Lung Carcinoma: Response to Therapy and Clinical Features in a Case Series of 14 Patients.

BACKGROUND: RET (rearranged during transfection) fusions have been reported in 1% to 2% of lung adenocarcinoma (LADC) cases. In contrast, KIF5B-RET and CCDC6-RET fusion genes have been identified in 70% to 90% and 10% to 25% of tumors, respectively. The natural history and management of RET-rearranged LADC are still being delineated. MATERIALS AND METHODS: We present a series of 14 patients with RET-rearranged LADC. The response to therapy was assessed by the clinical response and an avatar model in 2 cases. Patients underwent chemotherapy, targeted therapy, and immunotherapy. RESULTS: A total of 14 patients (8 women; 10 never smokers; 4 light smokers; mean age, 57 years) were included. KIF5B-RET and CCDC6-RET variants were diagnosed in 10 and 4 cases, respectively. Eight patients had an early disseminated manifestation, seven with KIF5B-RET rearranged tumor. The features of this subset included bilateral miliary lung metastases, bone metastases, and unusual early visceral abdominal involvement. One such patient demonstrated an early and durable complete response to cabozantinib for 7 months. Another 2 patients treated with cabozantinib experienced a partial response, with rapid significant clinical improvement. Four patients with tumors harboring CCDC6-RET and KIF5B-RET fusions showed pronounced and durable responses to platinum-based chemotherapy that lasted for 8 to 15 months. Two patients' tumors showed programmed cell death ligand 1-positive staining but did not respond to pembrolizumab. The median overall survival was 22.8 months. CONCLUSION: RET-rearranged LADC in our series tended to occur as bilateral disease with early visceral involvement, especially with KIF5B fusion. Treatment with cabozantinib achieved responses, including 1 complete response. However, further studies are required in this group of patients.

Cyprinid herpes virus-3 (CyHV-3) bears genes of genetically distant large DNA viruses.

A large DNA virus, designated koi herpes virus (KHV), carp interstitial nephritis gill necrosis virus (CNGV) and Cyprinid herpes virus-3 (CyHV-3), causes massive mortality of carp. Morphologically, the virus resembles herpes viruses, but it contains a genome of ca 295 kbp, larger than that of any Herpesviridae member. Interestingly, three CyHV-3 genes, thymidylate monophosphate kinase (TmpK), ribonucleotide reductase and thymidine kinase, which are involved in deoxynucleotide tri-phosphate synthesis, resemble those of pox viruses. In addition to the TmpK gene, which is nonexistent in the genome of herpes viruses, CyHV-3 contains a B22R-like gene, exclusively expressed by pox viruses. These results raise questions on the phylogenic origin of CyHV-3.

Exhaled Breath Analysis for Monitoring Response to Treatment in Advanced Lung Cancer.

INTRODUCTION: The Response Evaluation Criteria in Solid Tumors (RECIST) serve as the accepted standard to monitor treatment efficacy in lung cancer. However, the time intervals between consecutive computerized tomography scans might be too long to allow early identification of treatment failure. This study examines the use of breath sampling to monitor responses to anticancer treatments in patients with advanced lung cancer. METHODS: A total of 143 breath samples were collected from 39 patients with advanced lung cancer. The exhaled breath signature, determined by gas chromatography/mass spectrometry and a nanomaterial-based array of sensors, was correlated with the response to therapy assessed by RECIST: complete response, partial response, stable disease, or progressive disease. RESULTS: Gas chromatography/mass spectrometry analysis identified three volatile organic compounds as significantly indicating disease control (PR/stable disease), with one of them also significantly discriminating PR/stable disease from progressive disease. The nanoarray had the ability to monitor changes in tumor response across therapy, also indicating any lack of further response to therapy. When one-sensor analysis was used, 59% of the follow-up samples were identified correctly. There was 85% success in monitoring disease control (stable disease/partial response). CONCLUSION: Breath analysis, using mainly the nanoarray, may serve as a surrogate marker for the response to systemic therapy in lung cancer. As a monitoring tool, it can provide the oncologist with a quick bedside method of identifying a lack of response to an anticancer treatment. This may allow quicker recognition than does the current RECIST analysis. Early recognition of treatment failure could improve patient care.

Cancerous glucose metabolism in lung cancer-evidence from exhaled breath analysis.

Cancer cells prefer hyperglycolysis versus oxidative phosphorylation, even in the presence of oxygen. This phenomenon is used through the FDG-PET scans, and may affect the exhaled volatile signature. This study investigates the volatile signature in lung cancer (LC) before and after an oral glucose tolerance test (OGTT) to determine if tumor cells' hyperglycolysis would affect the volatile signature. Blood glucose levels and exhaled breath samples were analyzed before the OGTT, and 90 min after, in both LC patients and controls. The volatile signature was measured by proton transfer reaction mass spectrometry (PTR-MS). Twenty-two LC patients (age 66.6 ± 12.7) with adenocarcinoma (n = 14), squamous (n = 6), small cell carcinoma (n = 2), and twenty-one controls (age 54.4 ± 13.7; 10 non-smokers and 11 smokers) were included. All LC patients showed a hyperglycolytic state in their FDG-PET scans. Both baseline and post OGTT volatile signatures discriminate between the groups. The OGTT has a minimal effect in LC (a decrease in m/z 54 by 39%, p v = 0.0499); whereas in the control group, five masses (m/z 64, 87,88, 142 and 161) changed by -13%, -49%, -40% and -29% and 46% respectively. To conclude, OGTT has a minimal effect on the VOC signature in LC patients, where a hyperglycolytic state already exists. In contrast, in the control group the OGTT has a profound effect in which induced hyperglycolysis significantly changed the VOC pattern. We hypothesized that a ceiling effect in cancerous patients is responsible for this discrepancy.

Mitochondrial induction as a potential radio-sensitizer in lung cancer cells - a short report.

INTRODUCTION: Lung cancer is the leading cause of cancer death. Radiation therapy plays a key role in its treatment. Ionizing radiation induces cell death through chromosomal aberrations, which trigger mitotic catastrophe and apoptosis. However, many lung cancer patients show resistance to radiation. Dichloroacetate (DCA) is a small molecule that can promote mitochondrial activation by increasing the influx of pyruvate. Here, we tested whether DCA may increase the sensitivity of non-small cell lung cancer (NSCLC) cells to radiation through this mechanism. METHODS: Two representative NSCLC cell lines (A549 and H1299) were tested for their sensitivity to radiation with and without pre-exposure to DCA. The treatment efficacy was evaluated using a clonogenic survival assay. An extracellular flux analyzer was used to assess the effect of DCA on cellular oxygen consumption as a surrogate marker for mitochondrial activity. RESULTS: We found that DCA increases the oxygen consumption rate in both A549 and H1299 cells by 60% (p = 0.0037) and 20% (p = 0.0039), respectively. Pre-exposure to DCA one hour before radiation increased the cytotoxic death rate 4-fold in A549 cells (55 to 13%, p = 0.004) and 2-fold in H1299 cells (35 to 17%, p = 0.28) respectively, compared to radiation alone. CONCLUSION: Mitochondrial induction by DCA may serve as a radio-sensitizer in non-small cell lung cancer.

Insulin-like growth factor-1 receptor (IGF-1R) as a biomarker for resistance to the tyrosine kinase inhibitor gefitinib in non-small cell lung cancer.

BACKGROUND: The insulin-like growth factor-1 receptor (IGF-1R) pathway is known to play a role in the acquisition of resistance to epidermal growth factor receptor (EGFR)-specific tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC). However, its exact role in TKI resistance has so far remained unclear. Here, we interrogated the hypothesis that the IGF-1R may serve as a biomarker for, and may play a role in, intrinsic resistance to the EGFR-specific TKI gefitinib in NSCLC. METHODS: Total-IGF-1R and phosphorylated (p)-IGF-1R expression levels were related to gefitinib sensitivity in 23 NSCLC cell lines. This sensitivity was re-evaluated after knocking down IGF-1R expression and after IGF-1R up-regulation through exogenous IGF-1 expression. The utility of IGF-1R expression as a predictive biomarker was also evaluated by immunohistochemistry (IHC) in 98 primary NSCLC samples from patients treated with gefitinib. RESULTS: Seventeen of the cell lines tested were resistant to gefitinib, whereas 3 cell lines were sensitive. The three remaining cell lines showed intermediate values. Thirteen resistant cell lines were found to be positive for total-IGF-1R expression, while all the sensitive cell lines were negative, resulting in a positive predictive value (PPV) of 81% for total-IGF-1R to predict resistance. Seven resistant cell lines exhibited high p-IGF-1R levels, whereas all 3 sensitive cell lines were negative for p-IGF-1R, resulting in a PPV of 100% for p-IGF-1R to predict resistance. Neither a knock-down of IGF-1R expression nor an activation of the IGF1-R pathway through exogenous IGF-1 expression affected gefitinib sensitivity. In primary NSCLC tissues, IGF-1R expression was found to be significantly higher in patients with progressive disease, i.e., showing gefitinib resistance, as compared to those with a complete or partial response. CONCLUSIONS: IGF-1R acts as a predictor for resistance to gefitinib in NSCLC cell lines and NSCLC patients, but does not seem to play a role in the intrinsic resistance to this drug. High total-IGF-1R and p-IGR-1R levels may predict such a resistance. Since the underlying mechanism does not appear to be related to proliferation induction, alternative pathways should be explored.

Down-regulation of the cyprinid herpesvirus-3 annotated genes in cultured cells maintained at restrictive high temperature.

Cyprinid herpesvirus-3 (CyHV-3) is a member of the Alloherpesviridae, in the order Herpesvirales. It causes a fatal disease in carp and koi fish. The disease is seasonal and is active when water temperatures ranges from 18 to 28 °C. Little is known about how and where the virus is preserved between the permissive seasons. The hallmark of the herpesviruses is their ability to become latent, persisting in the host in an apparently inactive state for varying periods of time. Hence, it could be expected that CyHV-3 enter a latent period. CyHV-3 has so far been shown to persist in fish maintained under restrictive temperatures, while shifting the fish to permissive conditions reactivates the virus. Previously, we demonstrated that cultured cells infected with CyHV-3 at 22 °C and subsequently transferred to a restrictive temperature of 30 °C preserve the virus for 30 days. The present report shows that cultured carp cells maintained and exposed to CyHV-3 at 30 °C are abortively infected; that is, autonomous viral DNA synthesis is hampered and the viral genome is not multiplied. Under these conditions, 91 of the 156 viral annotated ORFs were initially transcribed. These transcripts were down-regulated and gradually shut off over 18 days post-infection, while two viral transcripts encoded by ORFs 114 and 115 were preserved in the infected cells for 18 days p.i. These experiments, carried out in cultured cells, suggest that fish could be infected at a high non-permissive temperature and harbor the viral genome without producing viral particles.

Coordinated and sequential transcription of the cyprinid herpesvirus-3 annotated genes.

Cyprinid herpesvirus-3 (CyHV-3) is the cause of a fatal disease in carp and koi fish. The disease is seasonal and appears when water temperatures range from 18 to 28°C. CyHV-3 is a member of the Alloherpesviridae, a family in the Herpesvirales order that encompasses mammalian, avian and reptilian viruses. CyHV-3 is a large double-stranded DNA (dsDNA) herpesvirus with a genome of approximately 295kbp, divergent from other mammalian, avian and reptilian herpesviruses, but bearing several genes similar to cyprinid herpesvirus-1 (CyHV-1), CyHV-2, anguillid herpesvirus-1 (AngHV-1), ictalurid herpesvirus-1 (IcHV-1) and ranid herpes virus-1 (RaHV-1). Here we show that viral DNA synthesis commences 4-8h post-infection (p.i.), and is completely inhibited by pre-treatment with cytosine ß-d-arabinofuranoside (Ara-C). Transcription of CyHV-3 genes initiates after infection as early as 1-2h p.i., and precedes viral DNA synthesis. All 156 annotated open reading frames (ORFs) of the CyHV-3 genome are transcribed into RNAs, most of which can be classified into immediate early (IE or α), early (E or ß) and late (L or γ) classes, similar to all other herpesviruses. Several ORFs belonging to these groups are clustered along the viral genome.