Navid Dashti; Forough Golsaz-Shirazi; Mahmood Jeddi-Tehrani; Amir-Hassan Zarnani; Mohammad Mehdi Amiri; Fazel Shokri
Abstract
Background: Since the outbreak of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), several vaccine candidates have been developed within a short period of time. Although the potency of these vaccines was evaluated individually, their comparative potency was not comprehensively ...
Read More
Background: Since the outbreak of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), several vaccine candidates have been developed within a short period of time. Although the potency of these vaccines was evaluated individually, their comparative potency was not comprehensively evaluated.Objective: To compare the immunogenicity and neutralization efficacy of four approved COVID-19 vaccines in Iran, including: PastoCovac Plus, Sinopharm, SpikoGen, and Noora in BALB/c mice.Methods: Different groups of female BALB/c mice were vaccinated with three doses of each vaccine. The serum levels of antibodies against the viral receptor binding domain (anti-RBD) and spike (anti-spike) protein as well as the vaccine formulation (anti-vaccine) were evaluated using enzyme-linked immunosorbent assay (ELISA). The neutralization efficacy of these four vaccines was assessed through four neutralization assays: conventional virus neutralization test (cVNT), pseudotype virus neutralization test (pVNT), surrogate virus neutralization test (sVNT), and inhibition flow cytometry.Results: All four vaccines induced seroconversion in vaccinated animals. All vaccines successfully induced high levels of anti-vaccine antibody; however, PastoCovac Plus and Sinopharm vaccines induced significantly higher levels of anti-RBD antibody titer compared to Noora and SpikoGen. Moreover, the results of the antibody response were corroborated by the virus neutralization tests, which revealed very weak neutralization potency by Noora and SpikoGen in all tests.Conclusion: Our results indicate significant immunogenicity and neutralization efficacy induced by PastoCovac Plus and Sinopharm, but not by Noora and SpikoGen. This suggests the need for additional comparative assessment of the potency and efficacy of these four vaccines in vaccinated subjects.
Mohammad Mehdi Amiri; Tannaz Bahadori; Tahereh Soltantoyeh; Reza Hosseini-Ghatar; Forough Golsaz-Shirazi; Mahmood Jeddi-Tehrani; Fazel Shokri
Reza Hosseini-Ghatar; Tahereh Soltantoyeh; Motahareh Bahadori; Jalal Khoshnoodi; Forough Golsaz-Shirazi; Mahmood Jeddi-Tehrani; Mohammad Mehdi Amiri; Fazel Shokri
Volume 14, Issue 3 , September 2017, , Pages 200-214
Abstract
Background: Human epidermal growth factor receptor 2 (HER2) has a crucial role in several malignancies. The extracellular domain of HER2 (HER2-ECD) has been extensively employed as an important target in passive and active immunotherapy. Isolated recombinant prokaryotic HER2-ECD subdomains were previously ...
Read More
Background: Human epidermal growth factor receptor 2 (HER2) has a crucial role in several malignancies. The extracellular domain of HER2 (HER2-ECD) has been extensively employed as an important target in passive and active immunotherapy. Isolated recombinant prokaryotic HER2-ECD subdomains were previously found to be ineffective in inducing anti-tumor antibody response. Objective: To employ recombinant eukaryotic HER2-ECD subdomains to raise anti-HER2 antibodies and determine their anti-tumor activity in vitro. Methods: Two paired subdomains of HER2-ECD (DI+II and DIII+IV), representing Pertuzumab and Trastuzumab binding domains, respectively, along with the full extracellular domain of HER2 were generated in CHO-K1 cells. Polyclonal antibodies were raised against these subdomains and characterized using ELISA, flow cytometry, and immunoblot and their anti-tumor activity was assessed by XTT assay. The cross-reactivity of these antibodies was specified along with other members of the human HER family. Results: Similar to Trastuzumab and anti-HER2-ECD antibody, anti-DI+II and DIII+IV polyclonal antibodies reacted with recombinant HER2-ECD and native HER2 expressed on tumor cells. These two polyclonal antibodies were able to inhibit the binding of Pertuzumab and Trastuzumab to HER2, respectively, and did not cross-react with other members of HER family. These antibodies were able to inhibit tumor cell growth in vitro, similar to Trastuzumab. Conclusion: The high immunogenicity of human HER2 DI+II and DIII+IV subdomains in rabbits and the tumor inhibitory activity of the purified specific antibodies imply that they might be suitable for active immunotherapy in formulation with appropriate adjuvants and in combination with other HER2 specific therapeutics.
Fateme Sadri-Ardalani; Moslem Ahmadi; Azam Hemmati; Shaghayegh Emami; Samira Farid; Mohammad Mehdi Amiri; Mahmood Jeddi-Tehrani; Mahdi Shabani; Fazel Shokri
Volume 14, Issue 2 , June 2017, , Pages 99-110
Abstract
Background: In addition to passive immunotherapy using anti-HER2 monoclonal antibodies, active immunotherapy via HER2 targeting is an interesting approach to inducing specific anti-tumor immune responses. We have recently reported the immunogenicity of HER2 subdomains following DNA immunization and HER2 ...
Read More
Background: In addition to passive immunotherapy using anti-HER2 monoclonal antibodies, active immunotherapy via HER2 targeting is an interesting approach to inducing specific anti-tumor immune responses. We have recently reported the immunogenicity of HER2 subdomains following DNA immunization and HER2 protein boosting. In the present study, we evaluated the immunogenicity of different HER2 extracellular subdomains for the induction of anti-HER2 antibody response in BALB/c mice. Objective: To investigate and characterize antibody responses to human recombinant proteins of HER2 extracellular subdomains in immunized mice. Methods: Four subdomains of HER2 extracellular domain were expressed in E.coli; subsequently, purified recombinant proteins were intraperitoneally injected in BALB/c mice with Freund's adjuvant. The anti-HER2 antibody response was detected by ELISA, immunoblotting and flow cytometry. Results: All the four HER2 subdomains along with the full extracellular domain (fECD) were able to induce specific anti-HER2 antibodies. Although anti-HER2 subdomains antibodies could not react with eukaryotic recombinant fECD protein by ELISA, they were able to recognize this protein by immunoblotting under both reduced and non-reduced conditions. Furthermore, only the sera of mice immunized with fECD protein could recognize native HER2 on HER2 overexpressing tumor cells (>99%) by flow cytometry. Moreover, fECD immunized mice sera inhibited the proliferation of tumor cells by XTT assay. Conclusion: The prokaryotic recombinant proteins of HER2 extracellular subdomains are immunogenic, yet the induced specific antibodies do not react with the native HER2 protein due to the paucity of post-translation modifications and /or distortion of the native conformation of isolated HER2 extracellular subdomains which might be potentially effective for induction of cell mediated immune response against HER2.
Ramina Fatemi; Ebrahim Mirzadegan; Zohreh Vahedian; Amir Hassan Zarnani; Mahmood Jeddi-Tehrani; Farah Idali
Volume 14, Issue 2 , June 2017, , Pages 159-171
Abstract
Background: 17β-estradiol (E2) has been known to modulate immune response. Recent studies indicate that E2 at pregnancy level plays a role in regulating T cell response. Objective: To investigate the optimum dose of E2 (from 10-9 to 10-7 M) in mediating the generation of regulatory T cells (Tregs), ...
Read More
Background: 17β-estradiol (E2) has been known to modulate immune response. Recent studies indicate that E2 at pregnancy level plays a role in regulating T cell response. Objective: To investigate the optimum dose of E2 (from 10-9 to 10-7 M) in mediating the generation of regulatory T cells (Tregs), using naïve human CD4+ T cells from healthy women. Methods: Naïve peripheral T cells were purified and conditioned with soluble anti-CD28 in anti-CD3-coated plates in the presence or absence of E2. Flow cytometry was employed to assess the expression pattern of forkhead boxP3 (FOXP3) and programmed death-1 (PD-1). Proliferation and cytokine secretions were analyzed, using XTT and ELISA assays. Results: In the presence of different doses of E2, the expression levels of anti-CD3/CD28 antibody-stimulated CD25/FOXP3 and FOXP3/PD-1 in conditioned T cells (cT) were peaked at 1 ng/ml (early pregnancy level, E2(1)) (47.14% (37.3-74.9) and 32% (27.7-52.5), respectively) and a slight, but not significant, increase after declining at 36 ng/ml (late pregnancy/pharmaceutical, E2(36)) (19.4% (15.2-24.5) and 15.8% (10.6-26.8), respectively). E2(1) cT showed a significantly reduced proliferation capacity (p<0.05) and secretion of IL-10 was enhanced in supernatants of E2(1 and 36) cT (p<0.05). In contrast to decreased TNF-a and IFN-g secretions in E2(1) cT supernatants, E2(36) stimulated TNF-a and IFN-g secretions (pConclusion: Our results indicate that the differential effect of E2 on generation of Tregs is consistent with the possibility that lower levels of pregnancy E2 are most efficient in induction of Tregs.
Motahareh Bahadori; Saeed Zarei; Amir Hassan Zarnani; Omid Zarei; Farah Idali; Reza Hadavi; Mahmood Jeddi-Tehrani
Volume 11, Issue 2 , June 2014, , Pages 97-104
Abstract
Background: Pro-inflammatory and anti-inflammatory cytokines and polymorphisms of their genes have been described to be involved in the pathogenesis of recurrent miscarriage (RM). Objective: To investigate the association between RM and five polymorphisms of cytokine genes, interleukin 10 (IL-10), (-592 ...
Read More
Background: Pro-inflammatory and anti-inflammatory cytokines and polymorphisms of their genes have been described to be involved in the pathogenesis of recurrent miscarriage (RM). Objective: To investigate the association between RM and five polymorphisms of cytokine genes, interleukin 10 (IL-10), (-592 A/C, -819 C/T, -1082 A/G), IL-6 (-174 C/G) and IL-17 (-197 G/A) in Iranian women. Method: Polymerase chain reaction -restriction fragment length polymorphism (PCR-RFLP) was performed to determine the frequencies of the IL-6, IL-10 and IL-17 gene polymorphisms in 85 women with RM compared with 104 healthy controls. Results: The frequencies of IL- 10 promoter gene polymorphisms (-592 A/C and -819 C/T) were significantly higher in RM women than those in controls (p=0.003). However, no statistically significant differences were observed in the frequencies of IL-6 (-174 C/G), IL-10 (-1082 A/G) and IL-17 (-197 G/A) polymorphisms between RM women and controls. Conclusion: These results suggest that IL-10 gene polymorphism screening might have some relevance in patients with RM, a suggestion which requires further studies.
Mahmood Shams; Mahmood Jeddi-Tehrani; Farzaneh Notash Haghighat; Ali Ahmad Bayat; Jafar Mahmoudian; Mohammad Reza Rezvani
Volume 10, Issue 4 , December 2013, , Pages 259-266
Abstract
Background: Human CD34 is a transmembrane glycoprotein which is expressed in human hematopoietic stem cells (HSCs) and the small- vessel endothelial cells of a variety of tissues. CD34 plays a critical role as a marker for diagnosis and classification of leukemia. Anti CD34 antibodies are used for isolation ...
Read More
Background: Human CD34 is a transmembrane glycoprotein which is expressed in human hematopoietic stem cells (HSCs) and the small- vessel endothelial cells of a variety of tissues. CD34 plays a critical role as a marker for diagnosis and classification of leukemia. Anti CD34 antibodies are used for isolation and purification of HSCs from bone marrow, peripheral blood and cord blood. Objective: To characterize a newly produced monoclonal antibody against a human CD34 peptide. Methods: Anti CD34 monoclonal antibody (Clone 2C10-D3) was purified from mouse ascitic fluid and hybridoma cell culture supernatants by affinity chromatography and its immune reactivity was examined by ELISA. The purified antibody was further characterized using Western blot and flow cytometry on TF1 (Human Erythroblast) cell line. Results: ELISA experiment revealed that the antibody recognized CD34 peptide. Western blot analysis on TF1 cell lysate confirmed the reactivity of the antibody with a 42 KDa protein. Blocking the antibody with a saturating concentration of specific CD34 peptide resulted in loss of its activity with TF1 lysate in Western blot. The 2C10-D3 antibody reacted with TF1 cells in flow cytometry in a similar manner to a commercial anti CD34 monoclonal antibody. Conclusions: Our data suggest that the anti CD34 monoclonal antibody (Clone 2C10-D3) is an appropriate antibody to study the CD34+ cells by flow cytometry and Western blot.
Forough Golsaz Shirazi; Mohammad Mehdi Amiri; Hamed Mohammadi; Ali Ahmad Bayat; Azam Roohi; Jalal Khoshnoodi; Amir Hassan Zarnani; Mahmood Jeddi-Tehrani; Gholam Ali Kardar; Fazel Shokri
Volume 10, Issue 3 , September 2013, , Pages 127-138
Abstract
Background: The antibody response to hepatitis B surface antigen (HBsAg) controls hepatitis B virus infection. The "a" determinant of HBsAg is the most important target for protective antibody response, diagnosis and immunoprophylaxis. Mutations in this area may induce immune escape mutants and affect ...
Read More
Background: The antibody response to hepatitis B surface antigen (HBsAg) controls hepatitis B virus infection. The "a" determinant of HBsAg is the most important target for protective antibody response, diagnosis and immunoprophylaxis. Mutations in this area may induce immune escape mutants and affect the performance of HBsAg assays. Objectives: To construct clinically relevant recombinant mutant forms of HBsAg and assessment of their reactivity with anti-HBs monoclonal antibodies (MAbs). Methods: Wild type (wt) and mutant (mt) HBsAg genes were constructed by site directed mutagenesis and SEOing PCR. The amplified genes were inserted into pCMV6-neo plasmid and transfected in CHO cell line. The expression of wt- and mtHBsAg was assessed by commercial ELISA assays and stable cells were established and cloned by limiting dilution. The recombinant mutants were further characterized using a panel of anti-HBs monoclonal antibodies (MAbs) and the pattern of their reactivity was assessed by ELISA. Results: Ten HBsAg mutants having single mutation within the "a" determinant including P120E, T123N, Q129H, M133L, K141E, P142S, D144A, G145R, N146S and C147S together with a wt form were successfully constructed and expressed in CHO cells. Reactivity of anti-HBs MAbs with mtHBsAgs displayed different patterns. The effect of mutations on antibody binding differed depending on the amino acid involved and its location within the ‘‘a’’ determinant. Mutation at amino acids 123 and 145 resulted in either complete loss or significant reduction of binding to all anti-HBs MAbs. Conclusion: Our panel of mtHBsAgs is a valuable tool for assessment of the antibody response to HBV escape mutants and may have substantial implications in HBV immunological diagnostics.
Samira Rajaei; Amir Hassan Zamani; Mahmood Jeddi-Tehrani; Maryam Tavakoli; Afsaneh Mohammadzadeh; Ali Dabbagh; Mahroo Mirahmadian
Volume 8, Issue 4 , December 2011, , Pages 201-208
Abstract
Background: Repeated Implantation Failure (RIF) is one of the most intricate obstacles in assisted reproduction. The cytokine and chemokine composition of uterine cavity seem to play important roles in the implantation process. Objective: To compare the cytokine profile in the endometrium of normal fertile ...
Read More
Background: Repeated Implantation Failure (RIF) is one of the most intricate obstacles in assisted reproduction. The cytokine and chemokine composition of uterine cavity seem to play important roles in the implantation process. Objective: To compare the cytokine profile in the endometrium of normal fertile women and those with repeated implantation failure. Methods: After enzymatic digestion of endometrial tissues, whole endometrial cells and endometrial stromal cells from RIF and normal fertile women were cultivated and stimulated for cytokine secretion. The levels of IL-10, TGF-β, IFN-γ, IL-6, IL-8 and IL-17 in culture supernatants of the two groups were assayed by ELISA and compared together. Results: Endometrial stromal cells and whole endometrial cells of normal fertile women produced higher levels of IL-6, IL-8 and TGF-β compared to RIF group, although this difference was statistically significant only in endometrial stromal cells (p=0.005, 0.002 and 0.001, respectively). In addition, endometrial stromal cells of normal fertile women produced lower levels of IL-10 in comparison with RIF group (p=0.005). Conclusion: Disturbances in cytokine production at the feto-maternal interface could be a cause of implantation failure. A pro-inflammatory cytokine milieu seems to be pivotal for successful implantation.
Sorour Shojaeian; Amir Hassan Zamani; Mahmood Jeddi-Tehrani; Forouzandeh Fereidooni; Ebrahim Torkabadi; Mohammad Mehdi Akhondi; Akram Sadat Tabatabaei-Panah; Abdolamir Allameh
Volume 6, Issue 4 , December 2009, , Pages 174-185
Abstract
Background: Monoclonal antibodies (mAbs) are essential tools for many molecular im-munology investigations, epitope mapping and molecular modelling, clinical laboratory di-agnostic tests and immunotherapy. Humoral immune response of immunized animals largely depends on the nature of antigen and the immunization ...
Read More
Background: Monoclonal antibodies (mAbs) are essential tools for many molecular im-munology investigations, epitope mapping and molecular modelling, clinical laboratory di-agnostic tests and immunotherapy. Humoral immune response of immunized animals largely depends on the nature of antigen and the immunization technique. Polysaccharides and heavily-glycosylated proteins are very elusive targets incapable of mounting long-lasting, high affinity antibody responses. Carcinoma antigen 125 (CA 125), a well known tumor marker of ovarian cancer, is a mucin type antigen consisting of repetitive units of heavily glycosylated moieties which render production of mAbs very difficult. Objective: To evaluate the efficacy of heterologous antigen preparations as a way of mouse immuniza-tion in the production of anti-CA 125 mAb. Methods: Two different protocols of immuni-zation were used for priming of NMRI mice. In the first method, mice conventionally im-munized by three intraperitoneal injections of purified CA 125 and boosted by the antigen three days before fusion. In the second approach, mice were primed by three intraperitoneal injections of living CA 125 positive cells of OVCAR-3 cell line, and boosted by intrave-nous injection of the purified extracellular domain of CA 125. Production of mAb was per-formed by standard hybridoma technology and mAbs were characterized by different im-munoassays. Results: The first method failed to produce stable clones despite six time fu-sion. A total of ten stable clones, however, were produced in the second approach. Some of the clones were characterized and found to have excellent immunoreactivity when tested by ELISA assay, western blotting, intracellular and surface immunofluorescent staining of OVCAR-3 cell line and immunohistochemical staining of ovarian cancer tissues. Conclusion: Altogether the results of the present study clearly showed that heterologous antigen preparation is the method of choice for immunization when production of mono-clonal antibody against highly glycosylated poorly immunogenic antigens is concerned.
Mohammad Hojjat Farasangi; Mahmood Jeddi-Tehrani; Seyed Mohsen Razavi; Ramazan Ali Sharifian; Ahmad Shamsian Khoramabadi; Hojatollah Rabbani; Fazel Shokri
Volume 5, Issue 1 , March 2008, , Pages 25-35
Abstract
Background: Patients with B-cell chronic lymphocytic leukemia (B-CLL) have hetero-geneous clinical courses, thus several biological parameters need to be added to the cur-rent clinical staging systems to predict disease outcome. Recent immunophenotypic stud-ies performed mainly in Western populations ...
Read More
Background: Patients with B-cell chronic lymphocytic leukemia (B-CLL) have hetero-geneous clinical courses, thus several biological parameters need to be added to the cur-rent clinical staging systems to predict disease outcome. Recent immunophenotypic stud-ies performed mainly in Western populations have demonstrated the prognostic value of CD38 and ZAP-70 expression in B-CLL. Objectives: To investigate the expression pat-tern of a variety of membrane antigens on leukemic cells from Iranian patients with CLL and to find out if there are any differences in the expression of these markers between in-dolent and progressive groups. Methods: In the present study, peripheral blood samples from 87 Iranian patients with B-CLL were analysed by flow cytometry. Results: In all cases, the neoplastic cells displayed B-CLL phenotype (CD5+/CD19+/sIg+). The vast ma-jority of the cases expressed CD23, but failed to stain for CD3 or CD14. The leukemic cells of most patients expressed CD27 (84/87, 95.4%) and CD45RO (74/87, 83.9%) molecules, suggesting a memory B-cell phenotype. Comparison between the indolent (n=42) and progressive (n=37) patients revealed significantly higher frequency and inten-sity of CD38 expression in progressive group (40.5%) compared to indolent (11.9%) pa-tients (p<0.05). None of the other membrane antigens were differentially expressed in these two groups of patients. Conclusion: Our results obtained in an Asian ethnic popula-tion confirm and extend previous findings obtained from Western populations regarding the association of CD38 expression and disease progression in B-CLL.
Saeed Zarei; Mahmood Jeddi-Tehrani; Mohammad Mehdi Akhondi; Hojjat Zeraati; Tahere Kheirkhah; Morteza Ghazanfari; Fazel Shokri
Volume 4, Issue 2 , June 2007, , Pages 101-109
Abstract
Background: Immunization against diphtheria, tetanus and pertussis has been applied in Iran since 1950. WHO suggests periodical evaluation of effectiveness of the triple diphtheria-tetanus-whole cell pertussis (DTwP) vaccine, worldwide. Objectives: To determine the immunogenicity of locally manufactured ...
Read More
Background: Immunization against diphtheria, tetanus and pertussis has been applied in Iran since 1950. WHO suggests periodical evaluation of effectiveness of the triple diphtheria-tetanus-whole cell pertussis (DTwP) vaccine, worldwide. Objectives: To determine the immunogenicity of locally manufactured DTwP vaccine administered to preschool children in a number of health centers of Tehran in 2006. Methods: In this prospective study, 350 children aged 4-6 years were injected with DTwP vaccine manu-factured by Razi Institute of Iran. Blood samples were collected before and 2-4 weeks after the vaccination. The immunogenicity of the vaccine was assayed by measurement of specific antibodies using enzyme-linked immunosorbent assay (ELISA) technique. Results: Of the 337 children who were vaccinated, 99.4% and 100% had protective anti-diphtheria and anti-tetanus antibody titers, respectively. The vaccine response and seroconversion for pertussis was achieved in 70.3% of the subjects. The geometric mean titers (GMT) of the antibodies produced against diphtheria, tetanus and pertussis by DTwP vaccine were 7.76, 9.37 IU/ml and 30.20 EU/ml after booster vaccine dose, respectively. Conclusions: Comparison of the results obtained from this study with those of previous studies performed in other countries reveals that immunogenicity of diphtheria and tetanus components is similar to other vaccines, but the immunogenicity of pertussis vaccine was less efficient. The lower immunogenicity of DTwP against pertussis may be related to the bacterial strain used or the formulation protocol adopted for the vaccine preparation.
Hossein Asgarian Omran; Mahdi Shabani; Tahereh Shahrestani; Abdolfattah Sarafnejad; Jalal Khoshnoodi; Parvaneh Vossough; Mohammad Faranoush; Ramzan A. Sharifian; Mahmood Jeddi-Tehrani; Hodjatallah Rabbani; Fazel Shokri
Volume 4, Issue 1 , March 2007, , Pages 15-25
Abstract
Background: Immunophenotypic characterization of the leukemic cells has been widely used as a tool for diagnosis, classification, stratification and prognosis of leukaemia. Objective: To investigate the immunophenotypic subtype profiles of Iranian patients with acute lymphoblastic leukemia (ALL) and ...
Read More
Background: Immunophenotypic characterization of the leukemic cells has been widely used as a tool for diagnosis, classification, stratification and prognosis of leukaemia. Objective: To investigate the immunophenotypic subtype profiles of Iranian patients with acute lymphoblastic leukemia (ALL) and its association to disease outcome. Methods: In this study, a total of 60 Iranian patients with ALL were immunophenotyped by flow cytometry using a panel of monoclonal antibodies specific for CD2, CD3, CD5, CD10, CD13, CD14, CD19, CD20, CD33, CD34, CD45, HLA-DR and TdT molecules. Results: The samples were initially categorized into T-ALL (n=9), B-ALL (n=50) and mixed lineage (n=1) based on the expression patterns of CD3 and CD19 molecules. B-ALL patients could further be classified into four subtypes, including Pro-B (n=7, 11.7%), Pre-B I (n=28, 46.7%), Pre-B II (n=13, 21.7%) and immature/mature B cells (n=2, 3.3%) on the basis of expression of CD10, CD19, CD20, HLA-DR and TdT. Clinical manifestations and laboratory findings of the patients did not reveal association with immunophenotypic sub-types of ALL, with the exception of mediastinal mass and WBC count at the time of diag-nosis which were found to be significantly higher in patients with T-ALL compared with B-ALL (p=0.001 and 0.014), respectively. Conclusion: Our results indicate that overall the immunophenotypic profile of Iranian ALL patients is similar to previous reports and it might be used for monitoring of minimal residual disease and prognosis.
