HB-EGF Is a Promising Therapeutic Target for Lung Cancer with Secondary Mutation of EGFRT790M.

Advanced lung cancer is one of the most lethal malignancies. Many anticancer agents have been developed for lung cancer with epidermal growth factor receptor (EGFR) mutations, but its prognosis remains extremely poor. The development of molecularly-targeted therapies is required for patients with lung cancer with secondary mutation of the EGFR gene. In this study, in order to assess the validity of heparin-binding EGF-like growth factor (HB-EGF) as a therapeutic target for lung cancer with EGFR mutation, we examined the antitumor effects of a specific inhibitor (cross-reacting material 197; CRM197) on lung cancer cells with EGFR mutation. HB-EGF was the most predominantly expressed EGFR ligand in lung cancer cells with EGFR mutation. CRM197 induced significant cell apoptosis and marked suppression of tumorigenicity in lung cancer cells with single or double mutation of EGFR. These results suggest that HB-EGF is a rational target for the treatment of lung cancer with EGFR mutation.

Antitumour Effects of Intravenous Administration of BK-UM, a Novel Inhibitor of HB-EGF, in Ovarian Cancer Therapy.

BACKGROUND: Patients with ovarian cancer with high levels of heparin-binding epidermal growth factor-like growth factor have a poor prognosis. Here we assessed the pharmacokinetics and tumour-inhibiting effects of cross-reacting material 197, produced commercially as BK-UM, and examined the efficacy and safety of its intravenous (i.v.) administration. MATERIALS AND METHODS: BK-UM was administered to rats, and its serum levels were measured. Ovarian cancer cell lines were either intraperitoneally (i.p.) or subcutaneously administered into mice, to establish a mouse model of ovarian cancer. BK-UM was then administered i.p. or i.v., and its tumour-inhibiting effects were examined. RESULTS: Higher maximum serum concentration (Cmax) values resulted from i.v. administration, whereas longer time to maximum serum (Tmax) values resulted from i.p. administration. In the peritoneal dissemination model, i.p. administration inhibited tumour growth and increased survival rate, whereas in the subcutaneous model, i.v. administration significantly inhibited tumour growth compared to i.p. administration. CONCLUSION: Administration of BK-UM by i.v. is both efficacious and safe.

BK-UM in patients with recurrent ovarian cancer or peritoneal cancer: a first-in-human phase-I study.

BACKGROUND: BK-UM (CRM197) is a mutant form of diphtheria toxin and a specific inhibitor of heparin-binding epidermal growth factor-like growth factor (HB-EGF). We assessed the safety, pharmacokinetics, recommended dose, and efficacy of BK-UM in patients with recurrent ovarian cancer (OC) or peritoneal cancer (PC), and measured HB-EGF levels in serum and abdominal fluid after BK-UM administration. METHODS: Eleven patients with advanced or recurrent OC or PC were enrolled and treated with BK-UM via the intraperitoneal route. The dose was escalated (1.0, 2.0, 3.3, and 5.0 mg/m2) using a 3 + 3 design. RESULTS: Eight of 11 patients completed treatment. No dose-limiting toxicity (DLT) was experienced at dose levels 1 (1.0 mg/m2) and 2 (2.0 mg/m2). Grade 3 transient hypotension as an adverse event (defined as a DLT in the present study) was observed in two of four patients at dose level 3 (3.3 mg/m2). Treatment with BK-UM was associated with decreases in HB-EGF levels in serum and abdominal fluid in seven of 11 patients and five of eight patients, respectively. Clinical outcomes included a partial response in one patient, stable disease in five patients, and progressive disease in five patients. CONCLUSIONS: BK-UM was well tolerated at doses of 1.0 and 2.0 mg/m2, with evidence for clinical efficacy in patients with recurrent OC or PC. A dose of 2.0 mg/m2 BK-UM is recommended for subsequent clinical trials. TRIAL REGISTRATION: This trial was prospectively performed as an investigator-initiated clinical trial. The trial numbers are UMIN000001002 and UMIN000001001, with registration dates of 1/30/2008 and 2/4/2008, respectively. UMIN000001001 was registered as a trial for the continuous administration of BK-UM after UMIN000001002 .

Anti-tumor Effect of Intravenous Administration of CRM197 for Triple-negative Breast Cancer Therapy.

BACKGROUND/AIM: Heparin-binding epidermal growth factor-like growth factor (HB-EGF), which belongs to the epidermal growth factor family, is a rational therapeutic target for triple-negative breast cancer (TNBC). This study aimed to assess the anti-tumor efficacy of intravenous (i.v.) HB-EGF-specific inhibitor (CRM197) for TNBC. MATERIALS AND METHODS: NOD/SCID mice were subcutaneously injected withTNBC cells, MDA-MB-231, and, then, treated with i.v. CRM197 in either dose- or frequency-dependent manners, using an advanced cancer model and an adjuvant therapy model. Tumor volume and mouse body weight were calculated weekly. Statistical significance was assessed by the Mann-Whitney U-test. RESULTS: Mice that received i.v. CRM197 showed a significant anti-tumor effect in dose- and frequency-dependent manners in both models. However, their body weight did not differ significantly among groups. CONCLUSION: These results suggest that i.v. CRM197 is an effective treatment for TNBC.

Incidences of Herpes Zoster and Postherpetic Neuralgia in Japanese Adults Aged 50 Years and Older From a Community-based Prospective Cohort Study: The SHEZ Study.

BACKGROUND: Many cross-sectional studies have examined the incidences of herpes zoster (HZ) and postherpetic neuralgia (PHN), but prospective studies in Japanese older adults are lacking. Therefore, we conducted a community-based prospective cohort study to determine the incidence in Japanese adults aged ≥50 years. METHODS: We recruited 12 522 participants from Shozu County, Kagawa Prefecture, between December 2008 and November 2009 and followed participants for 3 years. When a subject presented with symptoms suggestive of HZ, they were examined at collaborating medical institutions and cooperated with onset and recovery surveys (eg, measurement of varicella zoster virus-specific immunity and a pain survey). The hazard ratios (HRs) of HZ and PHN according to sex and age were analyzed by Cox regression analysis with a significance level of 5%. RESULTS: The incidence of HZ was 10.9/1000 person-years (men: 8.5/1000 person-years; women: 12.8/1000 person-years) and was significantly higher in women than in men (HR 1.5; 95% confidence interval, 1.2-1.8). The incidence of PHN was 2.1/1000 person-years (men: 1.7/1000 person-years; women: 2.4/1000 person-years), with no significant sex differences. A total of 19% of HZ cases progressed to PHN; no sex-specific difference in the proportion of PHN cases was observed. CONCLUSIONS: We clarified the accurate incidences of HZ and PHN in a population of Japanese older adults. These incidences increased with age. HZ incidence was higher in women than in men, while PHN incidence did not differ markedly between the sexes.

Evaluation of varicella zoster virus-specific cell-mediated immunity by using an interferon-γ enzyme-linked immunosorbent assay.

BACKGROUND: Administration of the varicella vaccine induces both varicella-zoster virus (VZV)-specific humoral and cell-mediated immunity (CMI). OBJECTIVE: To assess VZV-CMI, we developed an interferon γ enzyme-linked immunosorbent assay (IFN-γ ELISA) that measures the quantity of total IFN-γ in culture supernatants of human peripheral blood mononuclear cells. STUDY DESIGN: We evaluated this method by comparing the pre- and post-vaccination immune response in peripheral blood mononuclear cells of 30 healthy children who were administered an initial varicella vaccination at Konan Kosei hospital. RESULTS: IFN-γ ELISA showed well-validated results; CMI was not detectable pre-immunization but became detectable post-immunization. Seroconversion was detected in 92.6% of subjects by the immune adherence hemagglutination test; however, half of the subjects did not display an increase in CMI levels. We also compared the incidence of breakthrough varicella and herpes zoster development between CMI post-positive and post-negative vaccinees at 1-2years after the last VZV vaccination. Eight subjects had a history of varicella or herpes zoster exposure post-VZV vaccination. Two of them with post-negative CMI contracted breakthrough varicella 15-16months after the last vaccination, even though they had sufficient VZV-specific antibody levels to be considered seropositive and seroprotected. Conversely, the others with post-positive CMI did not contract breakthrough varicella, despite experiencing extensive VZV exposure through casual contact with playmates and family. CONCLUSIONS: The CMI data generated by this IFN-γ ELISA may accurately reflect real-world immune status, and CMI may be closely related to immunoprotection against breakthrough varicella development.

VZV skin-test reaction, but not antibody, is an important predictive factor for postherpetic neuralgia.

BACKGROUND: The decline of cell-mediated immunity (CMI) is thought to be related to the risk of postherpetic neuralgia (PHN) as well as herpes zoster (HZ). However, the relationship between immunological condition and the incidence of PHN is still unclear. OBJECTIVE: We conducted a large-scale prospective cohort study to clarify the relationship between immunological factors for varicella-zoster virus (VZV) and the incidence of PHN. METHODS: We carried out a cohort study on VZV immunity in a population living on an island cluster, Shozu County in Japan, and examined the people who developed HZ during a follow-up period of 3 years, with a focus on the relationship between cell-mediated and humoral immunity and the incidence of PHN. A total of 12,522 people over the age of 50 were enrolled in this study, and 401 registrants were diagnosed with HZ, including 79 PHN cases. We evaluated anatomical location and severity of skin lesion, acute pain severity, presence or absence of abnormal sensations, CMI assessed by VZV skin test, and VZV-specific antibody titer measured by serological tests. RESULTS: The incidence of PHN was significantly associated with a weak response to the VZV skin test, as well as facial or lumbosacral localization of skin rash, severe skin lesion, severe acute pain, and presence of abnormal sensations, but not related to VZV-specific antibody titer. CONCLUSION: The incidence of PHN is significantly associated with the decline of VZV-specific CMI, but not related to VZV-specific humoral immunity.

The efficacy of inactivated West Nile vaccine (WN-VAX) in mice and monkeys.

BACKGROUND: West Nile virus (WNV) belonging to the genus Flavivirus of the family Flaviviridae causes nervous system disorder in humans, horses and birds. Licensed WNV vaccines are available for use in horses but not for humans. We previously developed an inactivated West Nile virus vaccine (WN-VAX) using a seed virus from West Nile virus (WNV NY99) that was originally isolated in New York City in 1999. In this study, we report the immunogenicity of WN-VAX in both mice and non-human primates. FINDINGS: The WN-VAX immunized mice showed protection against lethal infection with WNV NY99. The challenge test performed on mice passively immunized with serum from other mice that were previously immunized with WN-VAX confirmed that the neutralizing antibody titers of more than 1log10 protected the passively immunized mice from WNV lethal infection. Furthermore, monkeys (Macaca fascicularis) immunized three times with 2.5 µg, 5 µg or 10 µg/dose of WN-VAX exhibited neutralizing antibodies in their sera with titers of more than 2log10 after the second immunization. CONCLUSIONS: The WN-VAX was protective in mice both by active and passive immunizations and was immunogenic in monkeys. These results suggest that the vaccine developed in this study may be a potential WNV vaccine candidate for human use.

Contribution of transcription factor, SP1, to the promotion of HB-EGF expression in defense mechanism against the treatment of irinotecan in ovarian clear cell carcinoma.

Ovarian clear cell carcinoma (OCCC) is a worst histological subtype than other ovarian malignant tumor. Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a promising target for ovarian cancer therapy. The aims of this study were to validate the efficacy of HB-EGF-targeted therapy for OCCC and to identify the transcription factor that contributed to the induction of HB-EGF by SN38 treatment in OCCC cells. HB-EGF was highly expressed in OCCC cells, and an increase of HB-EGF was induced by SN38 which had only antitumor effect among conventional anticancer agents on OCCC. A specific inhibitor of HB-EGF, a cross-reacting material 197 (CRM197), led to a synergistic increase in the number of apoptotic OCCC cells with the treatment of SN38. The luciferase assay with 5'-deletion promoter constructs identified a GC-rich element between -125 and -178 (the distal transcription start site was denoted +1) as a cis-regulatory region, and the treatment of SN38 induced luciferase activity in this region. An in silico and chromatin immunoprecipitation analysis estimated that SP1 bound to the cis-regulatory region of HB-EGF in OCCC cells. Real-time PCR and cell viability assays showed that the transfection of a small interfering RNA targeting SP1 suppressed the expression of HB-EGF induced by SN38, resulting in the enhanced sensitivity of SN38. Taken together, these results indicate that induction of HB-EGF expression contributed to defense mechanism against treatment of SN38 through the transcriptional activity of SP1 in OCCC cells.

Pre-clinical study of BK-UM, a novel inhibitor of HB-EGF, for ovarian cancer therapy.

BACKGROUND/AIM: Heparin-binding epidermal growth factor-like growth factor (HB-EGF), a member of the epidermal growth factor family, is a target for ovarian cancer therapy. The present study investigated the administration schedule of BK-UM, an anticancer agent targeting HB-EGF. MATERIALS AND METHODS: The ovarian cancer cell line, RMG-I, was injected subcutaneously into five-week-old female nude mice. The BK-UM was administered intraperitoneally, using three administration schedules with different doses. The tumor volume was calculated every week. Statistical significance was assessed using the Mann-Whitney U-test. RESULTS: At doses >0.1 mg/kg, BK-UM displayed significant antitumor effects, although the antitumor effects and body weights of mice did not significantly differ by dose or by three different administration schedules. At a dose <0.1 mg/kg, however, BK-UM had little inhibitory effect on tumor growth. CONCLUSION: Daily administration of BK-UM, which has a potentially dose-dependent antitumor effect, may be the optimal schedule for clinical application.

An inverse correlation of VZV skin-test reaction, but not antibody, with severity of herpes zoster skin symptoms and zoster-associated pain.

BACKGROUND: Cell-mediated immunity (CMI) has been considered to be related to the development of herpes zoster (HZ). However, there have been no large-scale prospective studies on the relationship between VZV-specific CMI and severity of HZ. OBJECTIVE: We carried out a large-scale prospective cohort study to clarify the relationship between immunological factors for varicella-zoster virus (VZV) and the clinical severity of HZ. METHODS: We carried out a cohort study on VZV immunity in a population living on an island cluster, Shozu County in Japan, and examined the people who developed HZ during a median follow-up period of 2 years, with a focus on the relationship between cell-mediated and humoral immunity and the severity of skin lesions and zoster-associated pain. A total of 12,522 people over the age of 50 were enrolled in this study, and 258 registrants were diagnosed as HZ. CMI was measured by VZV skin test, and humoral immunity was assessed with serological tests (neutralization test, immunoadherence hemagglutination test, and gpELISA test) for VZV-specific antibodies. RESULTS: CMI to VZV assessed by VZV skin test showed a significant inverse relationship to the severity of HZ skin lesions, and also to the severity of acute and subacute pain. Furthermore, weak response to the VZV skin test was associated with a high risk of post-herpetic neuralgia. In contrast, VZV-specific antibody titer was not associated with the severity of skin lesions and zoster-associated pain. CONCLUSION: VZV-specific CMI, but not humoral immunity, may play a key role in controlling the severity of HZ skin lesions and zoster-associated pain.

Intranasal immunization with a formalin-inactivated human influenza A virus whole-virion vaccine alone and intranasal immunization with a split-virion vaccine with mucosal adjuvants show similar levels of cross-protection.

The antigenicity of seasonal human influenza virus changes continuously; thus, a cross-protective influenza vaccine design needs to be established. Intranasal immunization with an influenza split-virion (SV) vaccine and a mucosal adjuvant induces cross-protection; however, no mucosal adjuvant has been assessed clinically. Formalin-inactivated intact human and avian viruses alone (without adjuvant) induce cross-protection against the highly pathogenic H5N1 avian influenza virus. However, it is unknown whether seasonal human influenza formalin-inactivated whole-virion (WV) vaccine alone induces cross-protection against strains within a subtype or in a different subtype of human influenza virus. Furthermore, there are few reports comparing the cross-protective efficacy of the WV vaccine and SV vaccine-mucosal adjuvant mixtures. Here, we found that the intranasal human influenza WV vaccine alone induced both the innate immune response and acquired immune response, resulting in cross-protection against drift variants within a subtype of human influenza virus. The cross-protective efficacy conferred by the WV vaccine in intranasally immunized mice was almost the same as that conferred by a mixture of SV vaccine and adjuvants. The level of cross-protective efficacy was correlated with the cross-reactive neutralizing antibody titer in the nasal wash and bronchoalveolar fluids. However, neither the SV vaccine with adjuvant nor the WV vaccine induced cross-reactive virus-specific cytotoxic T-lymphocyte activity. These results suggest that the intranasal human WV vaccine injection alone is effective against variants within a virus subtype, mainly through a humoral immune response, and that the cross-protection elicited by the WV vaccine and the SV vaccine plus mucosal adjuvants is similar.

The Shozu Herpes Zoster (SHEZ) study: rationale, design, and description of a prospective cohort study.

BACKGROUND: The incidence and risk factors for herpes zoster have been studied in cross-sectional and cohort studies, although most such studies have been conducted in Western countries. Evidence from Asian populations is limited, and no cohort study has been conducted in Asia. We are conducting a 3-year prospective cohort study in Shozu County in Kagawa Prefecture, Japan to determine the incidence and predictive and immunologic factors for herpes zoster among Japanese. METHODS: The participants are followed for 3 years, and a telephone survey is conducted every 4 weeks. The participants were assigned to 1 of 3 studies. Participants in study A gave information on past history of herpes zoster and completed health questionnaires. Study B participants additionally underwent varicella-zoster virus (VZV) skin testing, and study C participants additionally underwent blood testing. If the participants develop herpes zoster, we evaluate clinical symptoms, measure cell-mediated immunity and humoral immunity using venous blood sampling, photograph skin areas with rash, conduct virus identification testing by polymerase chain reaction (PCR) and virus isolation from crust sampling, and evaluate postherpetic pain. RESULTS: We recruited 12 522 participants aged 50 years or older in Shozu County from December 2009 through November 2010. The participation rate was 65.7% of the target population. CONCLUSIONS: The present study is likely to provide valuable data on the incidence and predictive and immunologic factors for herpes zoster in a defined community-based population of Japanese.

Superior immunogenicity of a freeze-dried, cell culture-derived Japanese encephalitis vaccine (inactivated).

Japanese encephalitis is an infectious disease caused by the Japanese encephalitis virus, which is widespread throughout Asia. The worldwide incidence is 50,000 cases per year. There is no specific treatment available, but inactivated mouse brain-derived vaccine was used from the 1950s to prevent infection. However, quality control of mouse brain-derived vaccines is difficult, and therefore a new freeze-dried, cell culture-derived Japanese encephalitis vaccine (inactivated) (JEBIK V; development code: BK-VJE) was developed. In this paper, we report an analysis of neutralizing antibody titers in vaccinated subjects enrolled in clinical study of BK-VJE at various doses, and study of BK-VJE with the mouse brain-derived vaccine as a control. The results show that BK-VJE has superior immunogenicity compared to mouse brain-derived vaccine.

Characterization of neutralizing antibodies in adults after intranasal vaccination with an inactivated influenza vaccine.

The levels and properties of neutralizing antibodies in nasal wash and serum collected from five healthy adults were examined after intranasal administration of an A/Uruguay/716/2007 (H3N2) split vaccine (45 µg hemagglutinin (HA) per dose; five doses, with an interval of 3 weeks between each dose). Prior to the assays, nasal wash samples were concentrated so that the total amount of antibodies was equivalent to about 1/10 of that found in the natural nasal mucus. Vaccination induced virus-specific neutralizing antibody responses, which increased with the number of vaccine doses given. Neutralizing antibodies were produced more efficiently in the nasal passages than in the serum: A ≥4-fold increase in nasal neutralization titres was observed after the second vaccination in four out of five subjects, whereas a rise in serum neutralization titres was observed only after the fifth vaccination. Nasal and serum neutralizing antibodies were mainly found in the polymeric IgA and monomeric IgG fractions, respectively, after gel filtration. Taken together, these results suggest that intranasal administration of an inactivated split vaccine induces high levels of nasal neutralizing antibodies (primarily polymeric IgA) and low levels of serum neutralizing antibodies (primarily monomeric IgG).

Poly-γ-glutamic acid nanoparticles and aluminum adjuvant used as an adjuvant with a single dose of Japanese encephalitis virus-like particles provide effective protection from Japanese encephalitis virus.

To maintain immunity against Japanese encephalitis virus (JEV), a formalin-inactivated Japanese encephalitis (JE) vaccine should be administered several times. The repeated vaccination is not helpful in the case of a sudden outbreak of JEV or when urgent travel to a high-JEV-risk region is required; however, there are few single-injection JE vaccine options. In the present study, we investigated the efficacy of a single dose of a new effective JE virus-like particle preparation containing the JE envelope protein (JE-VLP). Although single administration with JE-VLP protected less than 50% of mice against lethal JEV infection, adding poly(γ-glutamic acid) nanoparticles (γ-PGA-NPs) or aluminum adjuvant (alum) to JE-VLP significantly protected more than 90% of the mice. A single injection of JE-VLP with either γ-PGA-NPs or alum induced a significantly greater anti-JEV neutralizing antibody titer than JE-VLP alone. The enhanced titers were maintained for more than 6 months, resulting in long-lasting protection of 90% of the immunized mice. Although the vaccine design needs further modification to reach 100% protection, a single dose of JE-VLP with γ-PGA-NPs may be a useful step in developing a next-generation vaccine to stop a JE outbreak or to immunize travelers or military personnel.

Antitumor effects of CRM197, a specific inhibitor of HB-EGF, in T-cell acute lymphoblastic leukemia.

The therapeutic outcome for T-cell acute lymphoblastic leukemia (T-ALL) remains poor; thus, novel, targeted therapies are urgently needed. Recently, we showed that heparin-binding epidermal growth factor-like growth factor (HB-EGF), a member of the EGF family, is a promising target for the treatment of various types of cancer. The aim of the present study was to investigate whether HB-EGF is a therapeutic target for T-ALL, and to further elucidate the antitumor effects of a specific inhibitor of HB-EGF, cross-reacting material 197 (CRM197). We elucidated the expression of HB-EGF in T-ALL cell lines, and evaluated the effect of CRM197 on these cells alone or in combination with anticancer agent. The expression of EGFR and EGFR ligands was determined by flow cytometry, RT-PCR and real-time quantitative PCR. Induction of apoptosis was assessed by TUNEL assay. HB-EGF was strongly expressed by T-ALL cell lines, and the expression of both HB-EGF and EGFR was enhanced by doxorubicin. CRM197 induced apoptosis, and furthermore, the combination of CRM197 plus doxorubicin enhanced cytotoxicity in a T-ALL cell line. These results suggest that HB-EGF is a promising therapeutic target for T-ALL.

Assessment of HB-EGF levels in peritoneal fluid and serum of ovarian cancer patients using ELISA.

BACKGROUND: Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a rational target for ovarian cancer therapy. The aim of this study was to examine HB-EGF levels in the peritoneal fluid and serum of ovarian cancer (OVCA) patients. PATIENTS AND METHODS: Samples were collected from six healthy women, 21 OVCA patients, and 21 ovarian cyst patients. HB-EGF levels were measured using a sandwich ELISA kit and calculated using a parallel line assay. RESULTS: No significant difference between the slopes of the standard and sample curves was observed at an anti-HB-EGF antibody concentration of 1.6 µg/ml. HB-EGF levels in the peritoneal fluid and serum of OVCA patients were significantly higher than those in patients with ovarian cysts or controls. Serum HB-EGF levels were also significantly correlated with levels in peritoneal fluid in OVCA patients. CONCLUSION: We developed an assay for the exact measurement of HB-EGF levels in peritoneal fluid and serum.

Anti-influenza activity of marchantins, macrocyclic bisbibenzyls contained in liverworts.

The H1N1 influenza A virus of swine-origin caused pandemics throughout the world in 2009 and the highly pathogenic H5N1 avian influenza virus has also caused epidemics in Southeast Asia in recent years. The threat of influenza A thus remains a serious global health issue and novel drugs that target these viruses are highly desirable. Influenza A possesses an endonuclease within its RNA polymerase which comprises PA, PB1 and PB2 subunits. To identify potential new anti-influenza compounds in our current study, we screened 33 different types of phytochemicals using a PA endonuclease inhibition assay in vitro and an anti-influenza A virus assay. The marchantins are macrocyclic bisbibenzyls found in liverworts, and plagiochin A and perrottetin F are marchantin-related phytochemicals. We found from our screen that marchantin A, B, E, plagiochin A and perrottetin F inhibit influenza PA endonuclease activity in vitro. These compounds have a 3,4-dihydroxyphenethyl group in common, indicating the importance of this moiety for the inhibition of PA endonuclease. Docking simulations of marchantin E with PA endonuclease suggest a putative "fitting and chelating model" as the mechanism underlying PA endonuclease inhibition. The docking amino acids are well conserved between influenza A and B. In a cultured cell system, marchantin E was further found to inhibit the growth of both H3N2 and H1N1 influenza A viruses, and marchantin A, E and perrotein F showed inhibitory properties towards the growth of influenza B. These marchantins also decreased the viral infectivity titer, with marchantin E showing the strongest activity in this assay. We additionally identified a chemical group that is conserved among different anti-influenza chemicals including marchantins, green tea catechins and dihydroxy phenethylphenylphthalimides. Our present results indicate that marchantins are candidate anti-influenza drugs and demonstrate the utility of the PA endonuclease assay in the screening of phytochemicals for anti-influenza characteristics.

Purification and concentration of non-infectious West Nile virus-like particles and infectious virions using a pseudo-affinity Cellufine Sulfate column.

Affinity column chromatography is a promising method for the purification of flavivirus particles that can supplement or potentially replace diafiltration and sucrose density centrifugation. In this study, the purification of West Nile Virus (WNV) antigens via Cellufine Sulfate column chromatography was examined. Virus-like particles (VLPs) produced by the expression of the prM and E genes were separated from most of the contaminant proteins with 0.2-0.4M NaCl, but still retained their spherical forms and immunogenicity in mice. The column, with a 1 mL bed-volume, concentrated WN-VLPs a minimum of 15 fold from culture supernatants. A heparin analogue, suramin, competitively eluted WN-VLPs, but sulphated polysaccharides, such as heparin, heparin sulfate and dextran sulfate, did not. Furthermore, 2.4 × 109 plaque forming units of WNV and 196 µg of the viral antigens were recovered from 60 mL of infected culture medium at high yields (93% and 96%, respectively). These results indicate that, in addition to conventional methods, Cellufine Sulfate column chromatography is an effective preparation technique for WNV particulate antigens that does not impair the antigen virological characteristics.