Generation and Retention of Defective RNA3 from Cucumber Mosaic Virus and Relevance of the 2b Protein to Generation of the Subviral RNA

A defective RNA3 (D3Yα) of strain Y of cucumber mosaic virus (CMV-Y) was examined on host-specific maintenance, experimental conditions, and a viral factor required for its generation in plants. D3Yα was stably maintained in cucumber but not in tomato plants for 28 days post inoculation (dpi). D3Yα was generated in Nicotiana tabacum or N. benthamiana after prolonged infection in the second and the third passages, but not in plants of N. benthamiana grown at low temperature at 28 dpi or infected with CMV-Y mutant that had the 2b gene deleted. Collectively, we suggest that generation and retention of D3Yα depends on potential host plants and experimental conditions, and that the 2b protein has a role for facilitation of generation of D3Yα.

Host-specific adaptation drove the coevolution of leek yellow stripe virus and Allium plants

Host adaptation plays a crucial role in virus evolution and is a consequence of long-term interactions between virus and host in a complex arms race between host RNA silencing and viral RNA silencing suppressor (RSS) as counterdefense. Leek yellow stripe virus (LYSV), a potyvirus causing yield loss of garlic, infects several species of Allium plants. The unexpected discovery of an interspecific hybrid of garlic, leek, and great-headed (GH) garlic motivated us to explore the host-adaptive evolution of LYSV. Here, using Bayesian phylogenetic comparative methods and a functional assay of viral RSS activity, we show that the evolutionary context of LYSV has been shaped by the host adaptation of the virus during its coevolution with Allium plants. Our phylogenetic analysis revealed that LYSV isolates from leek and their taxonomic relatives (Allium ampeloprasum complex; AAC) formed a distinct monophyletic clade separate from garlic isolates and are likely to be uniquely adapted to AAC. Our comparative studies on viral accumulation indicated that LYSV accumulated at a low level in leek, whereas LYSVs were abundant in other Allium species such as garlic and its relatives. When RSS activity of the viral P1 and HC-Pro of leek LYSV isolate was analyzed, significant synergism in RSS activity between the two proteins was observed in leek but not in other species, suggesting that viral RSS activity may be important for the viral host-specific adaptation. We thus consider that LYSV may have undergone host-specific evolution at least in leek, which must be driven by speciation of its Allium hosts. IMPORTANCE Potyviruses are the most abundant plant RNA viruses and are extremely diversified in terms of their wide host range. Due to frequent host switching during their evolution, host-specific adaptation of potyviruses may have been shaped by numerous host factors. However, any critical determinants for viral host range remain largely unknown, possibly because of the repeated gain and loss of virus infectivity of plants. Leek yellow stripe virus (LYSV) is a species of the genus Potyvirus, which has a relatively narrow host range, generally limited to hosts in the genus Allium. Our investigations on leek and leek relatives (Allium ampeloprasum complex), which must have been generated through interspecies hybridization, revealed that LYSV accumulation remained low in leek as a result of viral host adaptation in competition with host resistance such as RNA silencing. This study presents LYSV as an ideal model to study the process of host-adaptive evolution and virus-host coevolution.

POS0530 MOLECULAR SIGNATURE IN SUSTAINED CLINICAL REMISSION INDUCED BY TOCILIZUMAB IN PATIENTS WITH RHEUMATOID ARTHRITIS

Background

Clinical remission is a clinical goal in the treatment of rheumatoid arthritis (RA). Sustained, biologics-free and true remission is an unachieved goal of the “treat-to-target” approach in most patients, and the determinants for achievement are still unclear. In our recent prospective study using multiomics analysis, we proposed that a molecular signature in peripheral whole blood can be a predictor for subsequent disease activity or activities of daily living.1 We also showed that tocilizumab (TCZ) induced deep clinical remission associated with gene expression in peripheral CD4+ T cells.2

Objectives

To consolidate and expand our hypothesis, we investigated the significance of molecular signatures in sustained remission in a larger scale cohort.

Methods

To build and validate the diagnostic model, we collected 73 peripheral blood samples from 30 patients with active RA, 30 patients in clinical remission induced by TCZ and 13 healthy controls. We then collected another 23 samples at a point before TCZ was halted due to sustained clinical remission. In total, 96 samples were analyzed by a multiomics platform, which included RNA sequencing and comprehensive proteomics.

Results

We first developed an optimized partial least-squares regression (PLSR) model using data from 5,436 genes and 255 proteins extracted in our previous model.1 The odds ratio in the model clearly reflected the clinical state with high fidelity (Figure 1). In that study, TCZ induced nearly half of the patients with clinical remission into molecular remission, with an odds ratio of less than zero. To clarify the characteristics of the molecular signature at sustained clinical remission under TCZ continuation, 23 samples were applied to the model. The odds ratio was largely the same as that for clinical remission. Next, we investigated the association with disease flare after cessation of TCZ. At some points before cessation, the median odds ratio in patients who experienced disease flare after stopping TCZ tended to be higher than that in patients with sustained remission after stopping TCZ in the transcriptomics model but not in the proteomics model. Thirty-five differentially expressed genes were identified between the two groups under the conditions of a >1.5-fold change and P-value<0.05.

Figure 1.

Odds ratio in the partial least-squares regression model using transcriptomics (A) and proteomics (B) data from rheumatoid arthritis and healthy control groups

Conclusion

Our larger scale study validated the idea in our previous study that TCZ induces molecular remission. A certain substantial gap associated with prognosis after quitting TCZ may exist as a molecular signature of sustained clinical remission induced by TCZ. These multiomics data sets enable us to understand sustained clinical remission at a molecular level.

References

[1]Nat Commun. 9(1):2775, 2018, 2) Sci Rep.11(1):16691, 2021

Graphs:

Acknowledgements

We acknowledge funding by Chugai Pharmaceutical Co., Ltd.

Disclosure of Interests

Nobuhiko Kajio: None declared, Katsuya Suzuki Speakers bureau: AbbVie, AsahiKasei, Astellas, Ayumi, Bristol-Myers Squibb, Chugai, Eisai, Eli Lilly, Gilead, Janssen, Mitsubishi Tanabe, Pfizer, Sanofi, Viatris, Consultant of: AbbVie, Asahi Kasei, Janssen, Pfizer, Grant/research support from: Chugai, Daiichi-Sankyo, Eli Lilly, Mitsubishi Tanabe, Ono, Takeda, Kotaro Matsumoto: None declared, Hiroshi Iijima: None declared, Seiji Nakamura: None declared, Yohei Ishizawa: None declared, Jun Inamo: None declared, Masaru Takeshita: None declared, Keiko Yoshimoto: None declared, Yuko Kaneko Speakers bureau: Chugai, Consultant of: Chugai, Grant/research support from: Chugai, Tsutomu Takeuchi Speakers bureau: Chugai, Consultant of: Chugai, Grant/research support from: Chugai.

POS0257 COMPARISON OF SARS-CoV-2 VACCINE RESPONSE IN PATIENTS WITH INFLAMMATORY RHEUMATIC DISEASE; mRNA-1273 VACCINE INDUCES HIGHER HUMORAL IMMUNOGENICITY THAN BNT162b2

Background

The SARS-CoV-2 messenger RNA (mRNA) vaccines BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) have benefitted all countries amid the coronavirus disease 2019 (COVID-19) crisis. Whereas both of them have shown efficacy in preventing COVID-19 illness in healthy participants, there is paucity of data about immunogenicity and safety of mRNA COVID-19 vaccines in patients with autoimmune, inflammatory rheumatic disease. Recent observational studies evaluated mainly BNT162b2, suggesting that glucocorticoids, immunosuppressive agents impair SARS-CoV-2 vaccine responses. However, difference in immune reactions and safety between BNT162b2 and mRNA-1273 have not been clarified in patients with inflammatory rheumatic diseases.

Objectives

To assess humoral and T cell immune responses and safety profiles after two doses of different mRNA vaccine against SARS-CoV-2; BNT162b2 and mRNA-1273.

Methods

We enrolled consecutive, previously uninfected patients with inflammatory rheumatic diseases receiving mRNA vaccine including BNT162b2 and mRNA-1273. Healthy participants receiving BNT162b2 were also recruited as control. Blood samples were obtained 3weeks, 2 months, 3 months, 4 months, and 6 months after second dose of vaccines. We measured titres of neutralizing antibodies against SARS-CoV-2 and calculated seroconversion rates to evaluate humoral responses. We also assessed T-cell immunity responses by using interferon releasing assay against SARS-CoV-2 in a part of the patients. Answers to questionnaires about adverse reactions were obtained from participants.

Results

A total of 974 patients with inflammatory rheumatic diseases and healthy 630 control participants were enrolled. Among them, 796 patients received BNT162b2, 178 patients received mRNA-1273, and all control participants received BNT162b2. Seroconversion rates and neutralizing antibody titres 3 weeks after vaccination were significantly higher in patients with mRNA-1273 and healthy participants with BNT162b2 compared with patients with BNT162b2; seroconversion rates, 97.2% vs 99.5% vs 83.3%, p<0.001; titers of neutralizing antibodies, 29.4±33.9 IU/mL vs 23.9±14.2 IU/mL vs 10.8±16.5 IU/mL, p<0.001, respectively. On another front, T cell reaction against SARS-CoV-2 was similar in both patients with mRNA-1273 and BNT162b2; interferon gamma levels for antigen 1, 1.2±2.1 IU/mL vs 0.8±2.5 IU/mL, p=0.23; and for antigen 2, 1.4±1.9 IU/mL vs 1.0±2.1 IU/mL, p=0.11, respectively. Regarding adverse reaction of each mRNA vaccine, the frequency of systemic adverse reactions including fever and general fatigue are also significantly higher in patients with mRNA-1273 and healthy controls than patients with BNT162b2; fever, 48.0% vs 44.9% vs 10.2%, p<0.001; general fatigue, 70.4% vs 61.8% vs 31.2%, p<0.001, respectively). In longitudinal measurement, neutralizing antibody titres in patients with BNT162b2 were decreased more rapidly than those in healthy controls; 3.3±3.2 IU/mL in patients with BNT162b2 at 4 months and 3.2±4.7 IU/mL in healthy controls with BNT162b2 at 6 months. We identified age, glucocorticoid dose (prednisolone > 7.5mg), use of immunosuppressants including methotrexate, mycophenolate, cyclophosphamide, and tacrolimus are associated with rapid attenuation of humoral responses in patients with BNT162b2.

Conclusion

Our results demonstrated a significant higher humoral immunogenicity and frequency of systemic adverse reaction of the SARS-CoV-2 mRNA-1273 (Moderna) compared with the BNT162b2 (Pfizer-BioNTech) in inflammatory rheumatic disease patients. Glucocorticoid and immunosuppressive agents impaired induction and sustention of neutralizing antibody, and earlier third booster vaccination may be required within 4 months, especially for those receiving BNT162b2.

References

[1]Steensels D, Pierlet N, Penders J et al. JAMA. 2021;326(15):1533–1535.

[2]Friedman MA, Curtis JR and Winthrop KL. Ann Rheum Dis 2021;80:1255–1265.

Disclosure of Interests

None declared

The C-terminal region of the 2a protein and 2b protein of cucumber mosaic virus are involved in the induction of shoestring-like leaf blade in tomato

Cucumber mosaic virus (CMV) has numerous strains with distinct pathological properties in nature. In this study, we focused on the distinct host-specificity of two isolates of CMV regarding induction of the shoestring-like leaf blade (SLB) in tomato (Solanum lycopersicum cv. Sekaiichi). During the initial infection stage, plants inoculated with CMV-D8 and CMV-Y developed green/yellow systemic mosaic and stunting. Late in infection, CMV-D8 caused severe systemic symptoms with SLB on the newly emerged leaves, whereas CMY-Y caused severe yellow mosaic with stunting. Accumulation of viral RNA of CMV-D8 during initial infection was higher than for CMV-Y, but their levels did not differ significantly at 5 weeks post inoculation. Pseudorecombination and recombination analyses between CMV-D8 and CMV-Y genomic RNAs showed that recombinant that contained the C-terminal region of 2a and the entire 2b protein of CMV-D8 (D2a-C/D2b) induced SLB. Changing isoleucine to valine at position 830 in the 2a ORF played an important role in formation of chronic SLB. We further elucidated that infection with CMV-D8 or the recombinant Y1Y2(D2a-C/D2b)D3, but not with CMV-Y, upregulated miRNAs and transcript levels of AGO1, which is involved in RNA silencing, and of HD-ZIP, TCP4, and PHAN, which are essential for leaf morphogenesis. The present results first demonstrated that the cooperative function of D2a-C/D2b is involved indispensably in SLB formation. In addition, we suggest that D2a-C/D2b region interferes with the miRNA pathway that is associated with RNA silencing and leaf morphogenesis, leading to the enhanced virulence of CMV-D8.

OP0128 DISTINCT FEATURES OF HLA-DR+ AND HLA-DR- PD-1HI CXCR5- T PERIPHERAL HELPER CELLS IN SEROPOSITIVE RHEUMATOID ARTHRITIS

Background:

PD-1hi CXCR5- T peripheral helper (Tph) cells are newly identified pathogenic CD4+ helper T cells in rheumatoid arthritis (RA). Since Tph cells have been emerged quite recently, the characteristics of Tph cells as a biomarker of RA are not fully understood.

Objectives:

The aim of the study is to evaluate how useful Tph cells in peripheral bloods are when compared to other immune cell subsets, and to clarify which Tph subset most accurately reflects the disease activity of RA.

Methods:

The RA patients who visited our rheumatology department between January 2000 and February 2017, and met the 2010 ACR/European League Against Rheumatism (EULAR) classification criteria were included. We first assessed correlation with 40 immune cell subsets and the disease activity of RA. Next, the proportions of these immune cells were compared between RA and healthy controls (HCs). We also investigated the immune cell subsets which reflected the time course change of the disease activity after the methotrexate (MTX) treatment. The study protocol was approved by the ethics committee at Keio University School of Medicine.

Results:

Thirty-four seropositive RA, 12 seronegative RA and 34 HCs were included. The Immune cell subsets which showed correlation with DAS28-ESR (r> 0.2 or r> -0.2) were activated CD4 T cells (r= 0.31), HLA-DR+Th1 cells (r= 0.20), HLA-DR+Th1-17 cells (r= 0.25), Tfh1-17 cells (r= -0.25), HLA-DR+Tph cells (r= 0.22), CD3+CD8+naïve T cells (r= -0.25), CD3+CD8+effector memory T cells (r= -0.26), plasma cells (r= 0.40) and CD14++CD16+intermediate monocyte (r= 0.23). The proportions of HLA-DR+Th1 cells (2.3% vs. 5.7%), HLA-DR+Th1-17 cells (0.7% vs. 2.2%), Tfh1-17 cells (1.7% vs. 2.0%), HLA-DR+Tph cells (0.02% vs. 0.1%), CD3+CD8+effector memory T cells (16.6% vs 25.7%), plasma cells (0.04% vs. 0.17%) were statistically higher in the patients with RA compared to HCs. While the proportion of Tph cells showed weak correlation with DAS28-ESR (r= 0.18), that was extremely higher in RA (0.08% vs. 0.25%). Interestingly, when assessing the correlations with the disease activity in seropositive and seronegative RA separately, the proportions of Tph cells (r= 0.52) and HLA-DR+Tph cells (r= 0.50) were highly reflected in seropositive RA, but not in seronegative RA. Regarding the disease activity after the MTX treatment, the change of proportion of Tph cells between week 0 and 52 significantly reflected the change of DAS28-ESR (r= 0.75, p= 0.025), but not HLA-DR+Tph cells because of the non-specific reduction by the MTX treatment. Rather, HLA-DR-Tph cells significantly reflected the change of DAS28-ESR while receiving the MTX treatment (r= 0.76, p= 0.021).

Conclusion:

Tph cells and HLA-DR+Tph cells highly reflected the disease activity of seropositive RA. However, after the treatment, the proportion of HLA-DR+Tph cells decreased independent from the disease activity, and that of HLA-DR-Tph cells more accurately reflected the change of the disease activity during the treatment.

References:

[1]Rao DA, et al. Pathologically expanded peripheral T helper cell subset drives B cells in rheumatoid arthritis. Nature. 2017;542:110-114.

Disclosure of Interests:

Hiroki Yamada: None declared, Takanori Sasaki: None declared, Katsuya Suzuki: None declared, Masaru Takeshita: None declared, Shuhei Tanemura Employee of: I am employed by Mitsubishi Tanabe Pharma Corporation, Noriyasu Seki Employee of: I am employed by Mitsubishi Tanabe Pharma Corporation, Hideto Tsujimoto Employee of: I am employed by Mitsubishi Tanabe Pharma Corporation, Tsutomu Takeuchi Grant/research support from: Eisai Co., Ltd, Astellas Pharma Inc., AbbVie GK, Asahi Kasei Pharma Corporation, Nippon Kayaku Co., Ltd, Takeda Pharmaceutical Company Ltd, UCB Pharma, Shionogi & Co., Ltd., Mitsubishi-Tanabe Pharma Corp., Daiichi Sankyo Co., Ltd., Chugai Pharmaceutical Co. Ltd., Consultant of: Chugai Pharmaceutical Co Ltd, Astellas Pharma Inc., Eli Lilly Japan KK, Speakers bureau: AbbVie GK, Eisai Co., Ltd, Mitsubishi-Tanabe Pharma Corporation, Chugai Pharmaceutical Co Ltd, Bristol-Myers Squibb Company, AYUMI Pharmaceutical Corp., Eisai Co., Ltd, Daiichi Sankyo Co., Ltd., Gilead Sciences, Inc., Novartis Pharma K.K., Pfizer Japan Inc., Sanofi K.K., Dainippon Sumitomo Co., Ltd.

THU0045 IDENTIFICATION OF NOVEL CENTROMERE AUTOANTIGENS IN SJÖGREN’S SYNDROME, SYSTEMIC SCLEROSIS AND PRIMARY BILIARY CHOLANGITIS

Background:

Anti-centromere antibodies (ACA) are detected in the serum of patients with various autoimmune diseases including Sjögren’s syndrome (SjS), systemic sclerosis (SSc) and primary biliary cholangitis (PBC). ACA positivity is correlated with clinical manifestations such as Raynaud’s phenomenon and sclerodactyly and these features are commonly seen across diseases. Although CENPB is thought to be the major antigen against ACA, autoimmune features of other centromere proteins have not been fully evaluated.

Objectives:

The aim of this study is to elucidate centromere autoantigens comprehensively and clarify their association with pathogenesis of SjS, SSc and PBC.

Methods:

A centromere protein library was created by cloning 6 single proteins and 10 complexes consisting of 35 proteins belonging to human centromere region. The centromere antigens were immobilized on beads and incubated in the serum of patients with SjS (n = 86), SSc (n = 35), PBC (n = 10), patients with two or more diseases above (n = 44), and healthy volunteers (n = 68). Autoantibodies to each centromere protein were analyzed by flow cytometry.

Results:

Patients had a wide variety of antibodies against most of centromere antigens including 4 newly identified autoantigens. The hierarchical clustering of each antigen distinguished 2 antigen clusters. The reactivity of autoantibodies against a centromere protein of one cluster was mutually correlated regardless of disease types, indicating that these proteins/protein complexes might be the target of ACA. In addition, our method enabled us to detect sera reacted against multiple centromere antigens in some of the ACA-negative patients with existing methods.

Conclusion:

We identified 4 novel centromere autoantigens and our data suggested that the main target of ACA was the protein complex rather than a single specific antigen in SjS, SSc and PBC patients. Using the combination of centromere proteins may be useful to detect ACA with higher sensitivity.

References:

[1]Fritzler MJ, Rattner JB, Luft LM, Edworthy SM, Casiano CA, Peebles C, Mahler M. Historical perspectives on the discovery and elucidation of autoantibodies to centromere proteins (CENP) and the emerging importance of antibodies to CENP-F. Autoimmun Rev. 2011;10:194-200.

Disclosure of Interests:

Nobuhiko Kajio: None declared, Masaru Takeshita: None declared, Katsuya Suzuki: None declared, Tsutomu Takeuchi Grant/research support from: Eisai Co., Ltd, Astellas Pharma Inc., AbbVie GK, Asahi Kasei Pharma Corporation, Nippon Kayaku Co., Ltd, Takeda Pharmaceutical Company Ltd, UCB Pharma, Shionogi & Co., Ltd., Mitsubishi-Tanabe Pharma Corp., Daiichi Sankyo Co., Ltd., Chugai Pharmaceutical Co. Ltd., Consultant of: Chugai Pharmaceutical Co Ltd, Astellas Pharma Inc., Eli Lilly Japan KK, Speakers bureau: AbbVie GK, Eisai Co., Ltd, Mitsubishi-Tanabe Pharma Corporation, Chugai Pharmaceutical Co Ltd, Bristol-Myers Squibb Company, AYUMI Pharmaceutical Corp., Eisai Co., Ltd, Daiichi Sankyo Co., Ltd., Gilead Sciences, Inc., Novartis Pharma K.K., Pfizer Japan Inc., Sanofi K.K., Dainippon Sumitomo Co., Ltd.

The 2b protein and C-terminal region of the 2a protein indispensably facilitate systemic movement of cucumber mosaic virus in radish with supplementary function by either the 3a or the coat protein

BACKGROUND

In Raphanus sativus (Japanese radish), strain D8 of cucumber mosaic virus (CMV-D8) establishes a systemic infection and induces mild mosaic on upper, non-inoculated leaves, whereas strain Y of CMV (CMV-Y) causes only a local infection in the inoculated leaves. Here, we further analyzed the specific viral factor(s) of CMV-D8 that is (are) indispensable for systemic infection in Japanese radish.

METHODS

To identify which genomic RNA(s) is (are) involved in systemic infection in radish, we carried out a pseudorecombination analysis between CMV-D8 and CMV-Y. With recombination analyses between CMV-D8 and CMV-Y using mutant/recombinant RNA2s, chimeric and point-mutated RNA3s, we identified viral factors that are indispensable for systemic infection.

RESULTS

Viral RNA2 and RNA3 of CMV-D8 facilitated efficient virus spread into the upper, non-inoculated plant tissues of radish (cv. Tokinashi), but not those of CMV-Y. Recombinant RNA2s demonstrated that the 2b protein (2b) and the C-terminus of the 2a protein (2a) of CMV-D8 have a crucial role in systemic infection. In addition, we used chimeric and point-mutated RNA3s to that Pro17 and Pro129 in the coat protein (CP) of CMV-D8 are involved in efficient systemic infection and that Ser51 in the 3a protein (3a) of CMV-D8 has positive effects on systemic spread. The results suggested that these viral factors facilitate systemic infection of CMV-D8 in Japanese radish.

CONCLUSION

The C-terminal region of 2a, the entire region of 2b, and supplementary function of either Ser51 in 3a or Pro17/Pro 129 in CP confer systemic infectivity on CMV-D8 in radish. These results further elucidate the complex interaction of viral proteins of CMV to complete systemic infection as a host-specific manner.

Role of salicylic acid glucosyltransferase in balancing growth and defence for optimum plant fitness

Salicylic acid (SA), an essential secondary messenger for plant defence responses, plays a role in maintaining a balance (trade-off) between plant growth and resistance induction, but the detailed mechanism has not been explored. Because the SA mimic benzothiadiazole (BTH) is a more stable inducer of plant defence than SA after exogenous application, we analysed expression profiles of defence genes after BTH treatment to better understand SA-mediated immune induction. Transcript levels of the salicylic acid glucosyltransferase (SAGT) gene were significantly lower in BTH-treated Nicotiana tabacum (Nt) plants than in SA-treated Nt control plants, suggesting that SAGT may play an important role in SA-related host defence responses. Treatment with BTH followed by SA suppressed SAGT transcription, indicating that the inhibitory effect of BTH is not reversible. In addition, in BTH-treated Nt and Nicotiana benthamiana (Nb) plants, an early high accumulation of SA and SA 2-O-β-d-glucoside was only transient compared to the control. This observation agreed well with the finding that SAGT-overexpressing (OE) Nb lines contained less SA and jasmonic acid (JA) than in the Nb plants. When inoculated with a virus, the OE Nb plants showed more severe symptoms and accumulated higher levels of virus, while resistance increased in SAGT-silenced (IR) Nb plants. In addition, the IR plants restricted bacterial spread to the inoculated leaves. After the BTH treatment, OE Nb plants were slightly larger than the Nb plants. These results together indicate that SAGT has a pivotal role in the balance between plant growth and SA/JA-mediated defence for optimum plant fitness.

Analysis of Symptom Development in Relation to Quantity of Rice stripe virus in Rice (Oryza sativa) to Simplify Evaluation of Resistance

Rice stripe virus (RSV) is one of the most devastating pathogens of rice (Oryza sativa) in rice-growing regions of East Asia. We analyzed the increase in RSV accumulation in infected rice plants over time and evaluated the association between disease severity and RSV accumulation with the aim of establishing an experimental system for accurate and efficient evaluation of RSV resistance in rice. As an index of RSV accumulation in plants, relative concentration of RNA corresponding to the coat protein gene region was measured using reverse-transcription quantitative polymerase chain reaction. Actin and elongation factor 1a were used as the host reference genes. RSV concentrations tended to increase with time from 7 to 28 days after inoculation, and a strong positive correlation was observed between the log RSV concentrations in the midsections of the uppermost leaves and in the stems at the first leaf sheath position. We analyzed RSV concentrations at these two locations 21 days after inoculation with RSV and assessed severity of disease symptoms based on a commonly used scale (Washio's six-grade scale) rated as A (most severe), B, Bt, C, Cr, or D (mild symptoms). RSV concentrations at both locations were high in plants graded A, B, or Bt, with no significant difference in concentration of RSV among the three grades, but concentrations were significantly higher in the three grades compared with that in the plants in grade D. RSV concentrations were highly variable among plants in grades C and Cr. On the basis of these data, we propose a new formula to estimate the range of disease severities with greater ease and practical value. The values calculated by the new formula corresponded well to those based on Washio's six-grade scale.

New insights into the photoswitching mechanisms of normal dithienylethenes

The photoswitching and competitive processes of the referent photochromic diarylethene derivative 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene (DTE) and a novel bridged analog DTE-m5 have been investigated by state-of-the-art TD-DFT calculations and ultrafast spectroscopy supported by advanced chemometric data treatments. Focusing on DTE, the overall deactivation pathway of both antiparallel (AP) and parallel (P) conformers of the open form (OF) (1 : 1 in solution) has been resolved and rationalized starting from the Franck-Condon (FC) region to the ground state recovery. For the photo-excited P conformer, after ultrafast relaxation (∼200 fs) towards the S₁ relaxed state, an expected ISC occurred (55 ps) to produce a triplet state, ³P, the latter relaxing within 2.5 μs. Concerning the AP conformer, the photocyclization reaction is reported to proceed immediately (100 fs) starting from the FC region while the relaxed singlet state is populated in parallel. For the first time, we discovered that the latter state evolves through an unexpected ISC process (1 ps) giving rise to a second triplet state,³AP. For DTE-m5, by slightly constraining the molecule with the bridge, this triplet becomes reactive and participates in the formation of 10% of closed form (CF) probably through an adiabatic mechanism. Concerning the photoreversion, in accordance with the literature, we report on a two-step process, a 190 fs vibrational relaxation followed by a 6 ps ring-opening reaction. For the overall species at the singlet or triplet manifold, the use of advanced MCR-ALS allows us to obtain specific spectral signatures. This study is therefore a new step within the comprehension of DTE photochemistry.

Interaction between Cucumber mosaic virus 2b protein and plant catalase induces a specific necrosis in association with proteasome activity

Cucumber mosaic virus (CMV) can induce a specific necrosis on Arabidopsis through the interaction between the CMV 2b protein and host catalase, in which the ubiquitin-proteasome pathway may be involved. We previously reported that the CMV 2b protein, the viral RNA silencing suppressor, interacted with the H₂O₂ scavenger catalase (CAT3), leading to necrosis on CMV-inoculated Arabidopsis leaves. We here confirmed that CMV could more abundantly accumulate in the CAT3-knockout mutant (cat3), and that CAT3 makes host plants a little more tolerant to CMV. We also found that the necrosis severity is not simply explained by a high level of H₂O₂ given by the lack of CAT3, because the recombinant CMV, CMV-N, induced much milder necrosis in cat3 than in the wild type, suggesting some specific mechanism for the necrosis induction. To further characterize the 2b-inducing necrosis in relation to its binding to CAT3, we conducted the agroinfiltration experiments to overexpress CAT3 and 2b in N. benthamiana leaves. The accumulation levels of CAT3 were higher when co-expressed with the CMV-N 2b (N2b) than with CMV-Y 2b (Y2b). We infer that N2b made a more stable complex with CAT3 than Y2b did, and the longevity of the 2b-CAT3 complex seemed to be important to induce necrosis. By immunoprecipitation (IP) with an anti-ubiquitin antibody followed by the detection with anti-CAT3 antibodies, we detected a higher molecular-weight smear and several breakdown products of CAT3 among the IP-proteins. In addition, the proteasome inhibitor MG132 treatment could actually increase the accumulation levels of CAT3. This study suggests that the host proteasome pathway is, at least partially, responsible for the degradation of CAT3, which is manifested in CMV-infected tissues.

A single amino acid at N-terminal region of the 2b protein of cucumber mosaic virus strain m1 has a pivotal role in virus attenuation

Host responses to infection by a mild strain of cucumber mosaic virus, termed CMV-m1, were re-examined in several plant species in comparison with those by a severe strain CMV-Y. Mild systemic symptoms were developed on the six plant species inoculated with CMV-m1. Virus titer in the Nicotiana benthamiana plants infected with CMV-m1 was significantly lower than those infected with CMV-Y, although infection by CMV-m1 interfered with further infection by CMV-Y in the plants. Subsequently, the attenuated virulence of CMV-m1 was analyzed by reassortment and recombination analyses between CMV-m1 and CMV-Y RNAs. The results suggested that the 2b protein of CMV-m1 (m1-2b) is involved in the formation of mild symptoms in N. benthamiana. Furthermore, site-directed mutagenesis demonstrated that Thr18 of m1-2b is responsible for formation of mild symptoms. Local RNA silencing suppressor activity of m1-2b was a little lower than that of severe strain CMV-Y. We discuss the relationship between attenuation of CMV-m1 and the features of m1-2b.

Genetic and serological characterization of chrysanthemum stem necrosis virus, a member of the genus Tospovirus

Chrysanthemum stem necrosis virus (CSNV) is a member of a tentative tospovirus species. In this study, the complete genomic sequence of the Japanese CSNV isolate TcCh07A was determined. The L RNA is 8960 nt long and encodes the 331.0-kDa RNA-dependent RNA polymerase. The M RNA is 4828 nt long and encodes the 34.1-kDa movement protein (NSm) and the 127.7-kDa glycoprotein precursor (Gn/Gc). The S RNA is 2949 nt long and encodes the 52.4-kDa silencing suppressor protein (NSs) and the 29.3-kDa nucleocapsid (N) protein. The N protein of CSNV-TcCh07A was purified from virus-infected plant tissues and used for production of a rabbit polyclonal antiserum (RAs) and a monoclonal antibody (MAb). Results of serological tests by indirect ELISA and western blotting using the prepared RAs and MAb and a previously produced RAs against the N protein of tomato spotted wilt virus (TSWV) indicated that CSNV-TcCh07A, TSWV, tomato chlorotic spot virus, groundnut ringspot virus, alstroemeria necrotic streak virus and impatiens necrotic spot virus are serologically related.

Induction of antiviral responses by acibenzolar-s-methyl against cucurbit chlorotic yellows virus in Melon

Cucurbit chlorotic yellows virus (CCYV) (family Closteroviridae, genus Crinivirus) is an emerging virus which causes severe diseases on melon (Cucumis melo) plants. CCYV-infected melon plants display yellowing, mottling, chlorosis, or chlorotic spots on leaves. To develop a new control strategy, the potential for 1,2,3-benzothiadiazole-7-thiocarboxylic acid-S-methyl-ester (ASM) to suppress CCYV infection was evaluated. ASM treatment on melon plants greatly increased the expression levels of pathogenesis-related 1a gene, a marker gene for systemic acquired resistance. ASM treatment on melon plants before inoculation of CCYV suppressed systemic symptoms and decreased CCYV accumulation. ASM treatment on melon even after inoculation of CCYV reduced disease severity and accumulation levels of CCYV. The results show the potential for ASM treatment on attenuation of the CCYV disease symptoms.

RCY1-mediated resistance to Cucumber mosaic virus is regulated by LRR domain-mediated interaction with CMV(Y) following degradation of RCY1

RCY1, which encodes a coiled coil nucleotide-binding site leucine-rich repeat (LRR) class R protein, confers the hypersensitive response (HR) to a yellow strain of Cucumber mosaic virus (CMV[Y]) in Arabidopsis thaliana. Nicotiana benthamiana transformed with hemagglutinin (HA) epitope-tagged RCY1 (RCY1-HA) also exhibited a defense response accompanied by HR cell death and induction of defense-related gene expression in response to CMV(Y). Following transient expression of RCY1-HA by agroinfiltration, the defense reaction was induced in N. benthamiana leaves infected with CMV(Y) but not in virulent CMV(B2)-infected N. benthamiana leaves transiently expressing RCY1-HA or CMV(Y)-infected N. benthamiana leaves transiently expressing HA-tagged RPP8 (RPP8-HA), which is allelic to RCY1. This result suggests that Arabidopsis RCY1-conferred resistance to CMV(Y) could be reproduced in N. benthamiana leaves in a gene-for-gene manner. Expression of a series of chimeric constructs between RCY1-HA and RPP8-HA in CMV(Y)-infected N. benthamiana indicated that induction of defense responses to CMV(Y) is regulated by the LRR domain of RCY1. Interestingly, in CMV(Y)-infected N. benthamiana manifesting the defense response, the levels of both RCY1 and chimeric proteins harboring the RCY1 LRR domain were significantly reduced. Taken together, these data indicate that the RCY1-conferred resistance response to CMV(Y) is regulated by an LRR domain-mediated interaction with CMV(Y) and seems to be tightly associated with the degradation of RCY1 in response to CMV(Y).

Infection dynamics in viral spread and interference under the synergism between Cucumber mosaic virus and Turnip mosaic virus

Mixed infection of Cucumber mosaic virus (CMV) and Turnip mosaic virus (TuMV) induced more severe symptoms on Nicotiana benthamiana than single infection. To dissect the relationships between spatial infection patterns and the 2b protein (2b) of CMV in single or mixed infections, the CMV vectors expressing enhanced green fluorescent or Discosoma sp. red fluorescent proteins (EGFP [EG] or DsRed2 [Ds], respectively were constructed from the same wild-type CMV-Y and used for inoculation onto N. benthamiana. CMV2-A1 vector (C2-A1 [A1]) has a functional 2b while CMV-H1 vector (C2-H1 [H1]) is 2b deficient. As we expected from the 2b function as an RNA silencing suppressor (RSS), in a single infection, A1Ds retained a high level of accumulation at initial infection sites and showed extensive fluorescence in upper, noninoculated leaves, whereas H1Ds disappeared rapidly at initial infection sites and could not spread efficiently in upper, noninoculated leaf tissues. In various mixed infections, we found two phenomena providing novel insights into the relationships among RSS, viral synergism, and interference. First, H1Ds could not spread efficiently from vasculature into nonvascular tissues with or without TuMV, suggesting that RNA silencing was not involved in CMV unloading from vasculature. These results indicated that 2b could promote CMV to unload from vasculature into nonvascular tissues, and that this 2b function might be independent of its RSS activity. Second, we detected spatial interference (local interference) between A1Ds and A1EG in mixed infection with TuMV, between A1Ds (or H1Ds) and TuMV, and between H1Ds and H1EG. This observation suggested that local interference between two viruses was established even in the synergism between CMV and TuMV and, again, RNA silencing did not seem to contribute greatly to this phenomenon.

Role of transcription factors in small intestinal ischemia-reperfusion injury and tolerance induced by ischemic preconditioning

BACKGROUND

Small intestinal ischemia-reperfusion (I/R) injury, a clinically important condition, induces severe organ damage. Ischemic preconditioning (IPC) produces tolerance to long-term I/R by inducing a short-term I/R. Herein, we have examined the reduction in the extent of injury by IPC.

METHODS

Small intestinal I/R injury was induced in rats by clamping the superior mesenteric artery (SMA) for 30 minutes followed by reperfusion for various 30 minutes. The IPC + I/R group underwent a short-term I/R (IPC) prior to long-term I/R. Nuclear factor-κB (NF-κB) activity was analyzed by an electrophoretic mobility shift assay and cytokine mRNA levels, by reverse transcription-polymerase chain reaction. Apoptosis-related genes were analyzed by Western blotting and immunohistochemistry, and apoptotic cells, by TUNEL staining.

RESULTS

The animals were subjected to 30 minutes of ischemia followed by 30 minutes of reperfusion. NF-κB activity increased in the I/R group and decreased in the IPC + I/R group. The IPC + I/R group showed decreased cytokine in mRNA levels. Expression of the proapoptotic gene caspase-3 was increased in the I/R and decreased in the IPC + I/R group. Expression of the antiapoptotic gene Bcl-xL was increased in the IPC + I/R group. The number of apoptotic cells was increased in the I/R and decreased in the IPC + I/R group.

CONCLUSION

Small intestinal I/R injury was reduced by IPC produced by clamping the SMA; thus, IPC may have potential clinical applications in the future.

The influence of RNA-dependent RNA polymerase 1 on potato virus Y infection and on other antiviral response genes

The gene encoding RNA-dependent RNA polymerase 1 (RDR1) is involved in basal resistance to several viruses. Expression of the RDR1 gene also is induced in resistance to Tobacco mosaic virus (TMV) mediated by the N gene in tobacco (Nicotiana tabacum cv. Samsun NN) in an incompatible hypersensitive response, as well as in a compatible response against Potato virus Y (PVY). Reducing the accumulation of NtRDR1 transcripts by RNA inhibition mediated by transgenic expression of a double-stranded RNA hairpin corresponding to part of the RDR1 gene resulted in little or no induction of accumulation of RDR1 transcripts after infection by PVY. Plants with lower accumulation of RDR1 transcripts showed much higher accumulation levels of PVY. Reduced accumulation of NtRDR1 transcripts also resulted in lower or no induced expression of three other antiviral, defense-related genes after infection by PVY. These genes encoded a mitochondrial alternative oxidase, an inhibitor of virus replication (IVR), and a transcription factor, ERF5, all involved in resistance to infection by TMV, as well as RDR6, involved in RNA silencing. The extent of the effect on the induced NtIVR and NtERF5 genes correlated with the extent of suppression of the NtRDR1 gene.

Impact of a defective RNA 3 from cucumber mosaic virus on helper virus infection dynamics

D RNA 3Yalpha (D3Yalpha), a defective (D) RNA 3 derived from the Y strain of cucumber mosaic virus (CMV-Y), was further characterized in combination with different helper viruses in the genus Cucumovirus. Interestingly, Nicotiana benthamiana plants inoculated with CMV-D8 and D3Yalpha developed systemic symptoms which were different from those induced by CMV-D8. To elucidate the potential effects of D RNA 3 on virus infection on the basis of the original combination of CMV-Y and D3Yalpha, a point mutation was made in the coat protein gene, which determined symptoms, of either CMV-Y RNA 3 (Y3) or D3Yalpha. Symptoms induced on N. benthamiana and N. tabacum plants, and semi-quantitative RT-PCR revealed that the ratio of RNA 3 to D RNA 3 was associated with the differences of symptoms in the leaf tissues. Furthermore, analysis of in situ hybridization suggested that there were spatial effects between coat proteins of Y3 and D3Yalpha in the infected leaves.

Characterization of a defective RNA derived from RNA 3 of the Y strain of cucumber mosaic virus

A defective (D) RNA 3 naturally generated from the Y strain of cucumber mosaic virus (CMV-Y) was characterized using a biologically active cDNA clone. Sequencing of the clone revealed that the D RNA 3, named D RNA 3Yalpha, was derived from CMV-Y RNA 3 and contained a 10 nt deletion in the 5' untranslated region and a 162 nt deletion within the 3a open reading frame. Co-inoculation of D RNA 3Yalpha with CMV-Y derived from in vitro transcripts facilitated propagation of CMV-Y containing D RNA 3Yalpha in Nicotiana benthamiana or Nicotiana tabacum plants. CMV-Y, however, did not produce deletion mutants upon serial mechanical passages in the plants.

Prevalence of hepatitis C virus infection in cases of B-cell lymphoma in Japan

AIMS

To determine the prevalence of hepatitis C virus (HCV) infection in B-cell lymphoma in Japan. HCV infection and type II (monoclonal IgM) cryoglobulinaemia (CG) may be involved in the pathogenesis of low-grade B-cell lymphoma (ML) in southern Europe.

METHODS AND RESULTS

Forty-five (11.3%) of 400 B-cell ML cases were HCV antibody (Ab) positive, which was significantly (P < 0.01) higher than the blood donors (2.5%). Among them, 28 diffuse large B-cell lymphoma (DLBCL) cases were included. In the primary sites, 10 (47.6%) of 21 splenic DLBCL and seven (23.3%) of 30 gastric DLBCL were HCV Ab positive, which were significantly (P < 0.05) higher than the myeloma cases (4.9%). HCV infection was rarely (4.2%) detected in 24 lymphoplasmacytic and salivary gland low-grade B-cell ML cases. Type II CG was detected in one myeloma case (3.5%) of 29 HCV+ B-cell ML. By real-time polymerase chain reaction, HCV RNA was detected in fresh tumour tissues of all 11 B-cell ML cases examined. Lymphoma cells were positive for the envelope HCV non-structural (NS)3 and envelope (E2) proteins in six of eight examined B-cell ML cases.

CONCLUSIONS

The rare incidence of type II CG is characteristic of Japanese HCV+ ML patients and may influence the low incidence of low-grade B-cell ML. HCV infection may play a role in lymphomagenesis of splenic and gastric DLBCL.

The wide distribution of endornaviruses, large double-stranded RNA replicons with plasmid-like properties

The International Committee on Taxonomy of Viruses (ICTV) recently accepted Endornavirus as a new genus of plant dsRNA virus. We have determined the partial nucleotide sequences of the RNA-dependent RNA polymerase regions from the large dsRNAs (about 14 kbp) isolated from barley (Hordeum vulgare), kidney bean (Phaseolus vulgaris), melon (Cucumis melo), bottle gourd (Lagenaria siceraria), Malabar spinach (Basella alba), seagrass (Zostera marina), and the fungus Helicobasidium mompa. Phylogenetic analyses of these seven dsRNAs indicate that these dsRNAs are new members of the genus Endornavirus that are widely distributed over the plant and fungal kingdoms.

Identification of Ki23819, a highly potent inhibitor of kinase activity of mutant FLT3 receptor tyrosine kinase

Constitutively active internal tandem duplication (ITD) in the juxtamembrane domain of Fms-like tyrosine kinase 3 (FLT3), a type III receptor tyrosine kinase, is the most common molecular defect associated with acute myeloid leukemia. Its presence confers a poor outcome in patients with acute myeloid leukemia who receive conventional chemotherapy. FLT3-ITD has therefore been considered to be an attractive molecular target for a novel therapeutic modality. We describe here the identification and characterization of Ki23819 as a novel FLT3 inhibitor. Ki23819 suppressed proliferation and induced apoptosis of FLT3-ITD-expressing human leukemia cell lines. The growth-inhibitory effect of Ki23819 on MV4-11 cells was superior to that of SU11248, another FLT3 inhibitor (IC(50)<1 vs 3-10 nM). Ki23819 inhibited the autophosphorylation of FLT3-ITD more efficiently than that of wild-type FLT3. FLT3-ITD-dependent activation of the downstream signaling proteins ERK and STAT5 was also inhibited within similar concentration ranges. Thus, Ki23819 is a potent in vitro inhibitor of FLT3.

Multiple organ failure caused by end-stage liver disease successfully treated with living donor liver transplantation using perioperative percutaneous cardiopulmonary support: a case report

A 54-year-old female diagnosed with primary biliary cirrhosis (PBC) 10 years earlier was referred for a living donor liver transplant (LDLT). During her workup, she developed pulmonary edema and respiratory failure due to aspiration pneumonia, which required artificial ventilation. The PaO2/FiO2 (P/F) ratio at that time was 60. Although continuous hemodiafiltration (CHDF) and plasma exchange (PE) were initiated, improvement in the P/F ratio was limited to 133. As transplantation was the only approach to save this patient, we performed LDLT using a right lobe graft aided by percutaneous cardiopulmonary support (PCPS). The graft weight was 650 g and the graft weight/recipient weight ratio was 1.6%. During LDLT, the patient's cardiopulmonary function was stable with PCPS, and the surgical procedure was completed without complications. Following the surgery, she continued to have high-end inspiratory pressure and progressed to the chronic phase of adult respiratory distress syndrome (ARDS). We treated her with low-dose steroid therapy and she improved gradually. The patient was weaned off mechanical ventilation and was discharged approximately 25 weeks after LDLT. In the condition of cardiac or respiratory failure, cadaveric liver transplantation using plasmapheresis is contraindicated because of the associated high mortality rate. Our case suggests that if infections are controlled, a patient with multiple organ failure (MOF) due to end-stage liver disease might be successfully treated with LDLT aided by plasmapheresis and PCPS.

Solid serous cystadenoma of the pancreas: MR imaging with pathologic correlation

We report a case of solid type serous cystadenoma of the pancreas. Computed tomographic and magnetic resonance (MR) images showed a hypervascular solid tumor that was difficult to differentiate from endocrine tumor of the pancreas. However, the tumor showed marked hyperintensity similar to that of hepatic cyst on MR cholangiopancreatography, indicating not a solid but rather a cystic nature. MR cholangiopancreatography (heavily T2-weighted image) is quite useful for clearly differentiating solid from cystic tumors.

Spatial analysis for exclusive interactions between subgroups I and II of Cucumber mosaic virus in cowpea

The dynamics of virus interference in Cucumber mosaic virus (CMV) infection in cowpea were investigated by tissue-blotting and in situ hybridization. Using co-inoculation assays, we discovered that spatial competition between CMV-LE (subgroup I) and CMV-m2 (subgroup II) occurred in the inoculated leaves. Interestingly, competitive interactions between the two viruses also could be observed in the non-inoculated upper leaf tissues of the plants. Furthermore, the pattern of exclusive distribution was observed between challenge and protecting viruses in the serially inoculated leaves. Taken together, it is suggested that the dynamics of competitive interactions between the two subgroups could be characterized by exclusive infection and multiplication of the individual viruses in cowpea plants.

Competition between wild-type virus and a reassortant from subgroups I and II of CMV and activation of antiviral responses in cowpea

To investigate the interactions between RNA3 and RNA4 from subgroups I and II in mixed infections, accumulation of CMV RNA were analyzed. In the mixed inoculation assays with CMV-LE (LE, subgroup I) and a reassortant LLm consisting of RNA1 and RNA2 from LE, and RNA3 from CMV-m2 (m2, subgroup II), LE RNA3 and RNA4 could systemically spread in the plants, whereas those of m2 could not. Furthermore, accumulation of virus short RNA and a cowpea-encoded RNA-directed RNA polymerase gene (VuRdRP1) mRNA were found in the plants, suggesting that VIGS and/or distinct antiviral responses (was) were activated by infection with CMV.

Reverse seroconversion of hepatitis B virus after hematopoietic stem cell transplantation

Hepatitis B virus (HBV) reactivation in patients previously positive for hepatitis B surface antibody (HBsAb), so-called reverse seroconversion, has been considered to be a rare complication after hematopoietic stem cell transplantation (HSCT). We experienced two patients who developed reverse seroconversion among nine who were HBsAb positive and Hepatitis B core antibody (HBcAb) positive before HSCT; one after autologous bone marrow transplantation (BMT) and another after allogeneic peripheral blood stem cell transplantation (PBSCT). We reviewed the literature and considered that reverse seroconversion of HBV after HSCT is not uncommon among HBsAb positive recipients. The use of corticosteroids, the lack of HBsAb in donor, and a decrease in serum HBsAb and HBcAb levels may predict reverse seroconversion after HSCT.

Carcinoma of the colon metastatic to the lower gingiva

A case of carcinoma of the colon that metastasized to the lower gingiva is described. The patient who had carcinoma of the colon developed a proliferating lesion at the site of a recent tooth extraction. A few days later, the primary site of the malignancy appeared. The clinical features in such cases were reviewed in studies by others, most of which were of oral and dental surgery. Thus, because of our case, gastroenterologists should consider the possibility of gingival metastasis from malignant disease such as colorectal cancer.