A resonant sextuplet of sub-Neptunes transiting the bright star HD 110067

Planets with radii between that of the Earth and Neptune (hereafter referred to as 'sub-Neptunes') are found in close-in orbits around more than half of all Sun-like stars1,2. However, their composition, formation and evolution remain poorly understood3. The study of multiplanetary systems offers an opportunity to investigate the outcomes of planet formation and evolution while controlling for initial conditions and environment. Those in resonance (with their orbital periods related by a ratio of small integers) are particularly valuable because they imply a system architecture practically unchanged since its birth. Here we present the observations of six transiting planets around the bright nearby star HD 110067. We find that the planets follow a chain of resonant orbits. A dynamical study of the innermost planet triplet allowed the prediction and later confirmation of the orbits of the rest of the planets in the system. The six planets are found to be sub-Neptunes with radii ranging from 1.94R⊕ to 2.85R⊕. Three of the planets have measured masses, yielding low bulk densities that suggest the presence of large hydrogen-dominated atmospheres.

Geriatric nutritional risk index as the prognostic factor in older patients with fragility hip fractures

This study investigated the long-term survival and incidence of secondary fractures after fragility hip fractures. The 5-year survival rate was 62%, and the mortality risk was seen in patients with GNRI < 92. The 5-year incidence of secondary fracture was 22%, which was significantly higher in patients with a BMI < 20.

BACKGROUND

Malnutrition negatively influences the postoperative survival of patients with fragility hip fractures (FHFs); however, little is known about their association over the long term.

OBJECTIVE

This study evaluated the ability of the geriatric nutritional risk index (GNRI) as a risk factor for long-term mortality after FHFs.

METHODS

This study included 623 Japanese patients with FHFs over the age of 60 years. We prospectively collected data on admission and during hospitalization and assessed the patients' conditions after discharge through a questionnaire. We examined the long-term mortality and the incidence of secondary FHFs and assessed the prognostic factors.

RESULTS

The mean observation period was 4.0 years (range 0-7 years). The average age at the time of admission was 82 years (range 60-101 years). The overall survival after FHFs (1 year, 91%; 5 years, 62%) and the incidence of secondary FHFs were high (1 year, 4%; 5 years, 22%). The multivariate Cox proportional hazard analysis revealed the risk factors for mortality as older age (hazard ratio [HR] 1.04), male sex (HR 1.96), lower GNRI score (HR 0.96), comorbidities (malignancy, HR 2.51; ischemic heart disease, HR 2.24; revised Hasegawa dementia scale ≤ 20, HR 1.64), no use of active vitamin D3 on admission (HR 0.46), and a lower Barthel index (BI) (on admission, HR 1.00; at discharge, HR 0.99). The GNRI scores were divided into four risk categories: major risk (GNRI, < 82), moderate risk (82-91), low risk (92-98), and no risk (> 98). Patients at major and moderate risks of GNRI had a significantly lower overall survival rate (p < 0.001). Lower body mass index (BMI) was also identified as a prognostic factor for secondary FHFs (HR 0.88 [p = 0.004]).

CONCLUSIONS

We showed that older age, male sex, a lower GNRI score, comorbidities, and a lower BI are risk factors for mortality following FHFs. GNRI is a novel and simple predictor of long-term survival after FHFs.

Chimeric flavivirus causes vascular leakage and bone marrow suppression in a mouse model

Previously, we demonstrated the utility of a recombinant chimeric flavivirus (DV2ChimV), which carries the premembrane (prM) and envelope (E) genes of a type 2 DENV clinical (Thai) isolate on a backbone of Japanese encephalitis virus, for evaluating the protective efficacy of antidengue envelope antibodies both in vitro and in vivo. Here, to assess the potential use of this model for pathological studies, we aimed to characterize interferon-α/β-γ-receptor double-knockout mice (IFN-α/β/γR dKO mice) infected with DV2ChimV. Vascular leakage and bone marrow suppression are unique features of severe dengue. In the current model, DV2ChimV caused vascular leakage in the liver and intestine at the moribund stage. High levels of virus were detected in the bone marrow, and strong bone marrow suppression (i.e., disappearance of megakaryocytes and erythroblastic islets) was observed. These observations suggest that the DV2ChimV-infected mouse model mimics the vascular leakage and bone marrow suppression observed in human cases.

Effects of various disaccharide adaptations on recombinant IgA1 production in CHO-K1 suspension cells

Immunoglobulin A (IgA) has been showing potential as a new therapeutic antibody. However, recombinant IgA suffers from low yield. Supplementation of the medium is an effective approach to improving the production and quality of recombinant proteins. In this study, we adapted IgA1-producing CHO-K1 suspension cells to a high concentration (150 mM) of different disaccharides, namely sucrose, maltose, lactose, and trehalose, to improve the production and quality of recombinant IgA1. The disaccharide-adapted cell lines had slower cell growth rates, but their cell viability was extended compared to the nonadapted IgA1-producing cell line. Glucose consumption was exhausted in all cell lines except for the maltose-adapted one, which still contained glucose even after the 9th day of culturing. Lactate production was higher among the disaccharide-adapted cell lines. The specific productivity of the maltose-adapted IgA1-producing line was 4.5-fold that of the nonadapted line. In addition, this specific productivity was higher than in previous productions of recombinant IgA1 with a lambda chain. Lastly, secreted IgA1 aggregated in all cell lines, which may have been caused by self-aggregation. This aggregation was also found to begin inside the cells for maltose-adapted cell line. These results suggest that a high concentration of disaccharide-supplemented induced hyperosmolarity in the IgA1-producing CHO-K1 cell lines. In addition, the maltose-adapted CHO-K1 cell line benefited from having an additional source of carbohydrate.

Shedding of rubella virus in postsymptomatic individuals; viral RNA load is a potential indicator to estimate candidate patients excreting infectious rubella virus

BACKGROUND

Since the first isolation of rubella virus (RuV) in 1962, comprehensive data regarding the quantitative evaluation of RuV shedding remain unavailable. In this study, we evaluated the shedding of viral RNA and infectious virus in patients with acute RuV infection.

STUDY DESIGN

We analyzed 767 specimens, including serum/plasma, peripheral blood mononuclear cells (PBMCs), throat swabs, and urine, obtained from 251 patients with rubella. The viral RNA load and the presence of infectious RuV were determined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and virus isolation.

RESULTS

Virus excretion peaked 0-2 days after rash onset and decreased over time. The median viral RNA load dropped to an undetectable level on day 3 after rash onset in serum/plasma, day 2 in PBMCs, days 10-13 in throat swabs, and days 6-7 in urine. Infectious virus could be isolated for up to day 2 after rash onset in serum/plasma, day 1 in PBMCs, days 8-9 in throat swabs, and days 4-5 in urine. The minimum viral RNA load that allowed virus isolation was 961 copies/mL in serum/plasma, 784 copies/mL in PBMCs, 650 copies/mL in throat swabs, and 304 copies/mL in urine. A higher viral RNA load indicated a higher likelihood of the presence of infectious virus.

CONCLUSION

These findings would contribute to improve algorithms for rubella surveillance and diagnosis. In addition, this study indicates that the results of RT-qPCR enable efficient rubella control by estimating candidate patients excreting infectious virus, which could help prevent viral transmission at an early stage and eliminate rubella ultimately.

Polyethyleneimine-modified resins effectively remove porcine circovirus and cellular prion protein

Polyethyleneimine (PEI) possesses various molecular weights (MWs), structures, and virus capture capacities. However, whether PEI can capture porcine circovirus (PCV) and animal cell-derived prion protein (PrP^C) that may contaminate source materials is unclear. Therefore, we conducted a feasibility study to assess the effectiveness of PEI in removing PCV and PrP^C as a model of pathogenic prions. The removal performance of PCV was evaluated by quantitative PCR using PEIs with various MWs, structures, and ion exchange capacities in Tris (pH 7.5) and acetate (pH 5.5) buffers under neutral (pH 7.5) to acidic (pH 5.5) conditions. Removal performances of PrP^C were also evaluated by western blotting using PEIs with various MWs and structures. Tris buffer did not affect the ability of PEI-modified resins to remove PCV, whereas acetate buffer affected removal performances, except those of PEI-10K-Br and PEI-70K-Br, which showed high ion-exchange capacities. PrP^C was captured by PEIs with high MWs, especially PEI-70K-Br, which was the most effective. The results of this feasibility study suggested that PEI-modified resin could remove PCV and PrP^C. PEI-70K-Br with an ion-exchange capacity of at least 0.3 meq/mL appears suitable as a PEI molecule for pathogen capture or removal of PCV or PrP^C from biological materials.

Virus Neutralization by Human Intravenous Immunoglobulin Against Influenza Virus Subtypes A/H5 and A/H7

Purpose

Highly pathogenic avian influenza viruses are a threat to human health. Although donor populations have not experienced pandemic, they have been immunized by natural infections and/or vaccinations of influenza viruses such as A/H1N1, A/H3N2, and B. Therefore, it is considered that human intravenous immunoglobulin (IVIG) derived from healthy donors does not include IgG against avian influenza viruses. However, cross-reactivity has not been evaluated yet. In this study, cross-reactivity against the avian influenza virus A/H5N1, A/H7N1, A/H7N2, A/H7N7, A/H7N9, and A/H10N9 was evaluated.

Materials and Methods

Several lots of IVIG derived from healthy donors in Japan were tested for virus neutralization using single- or multi-cycle virus neutralizing (S-VN or M-VN) assays that evaluate the infection-step associated with HA or the infection and propagation steps associated with HA and NA, respectively. In addition, anti-NA activities were evaluated by inhibiting the enzymatic activity in NAI assays.

Results

IVIG lots showed high neutralizing activities against three A/H5N1 strains in M-VN assays, whereas activities in S-VN assays were unstable. In addition, A/H7N2 was also neutralized in S-VN and M-VN assays, with higher activity in M-VN than in S-VN assays. A/H7N1 was neutralized in S-VN and M-VN assays. In contrast, weak or no activity against A/H7N7, A/H7N9, and A/H10N9 was observed in S-VN and M-VN assays. NAI assay results show that IVIG lots had inhibitory activities against N1 and N2; however, N2 activities differed depending on the strain. In contrast, no activities were observed against N7 and N9.

Conclusion

These results suggest that IVIG lots have neutralizing activity against avian influenza viruses during the virus propagation step, except for one strain, although no or weak activity was observed during the infection step.

Two Different Strains of Severe Fever with Thrombocytopenia Syndrome Virus (SFTSV) in North and South Osaka by Phylogenetic Analysis of Evolutionary Lineage: Evidence for Independent SFTSV Transmission

Severe fever with thrombocytopenia syndrome (SFTS) is a novel tick-borne infectious disease, therefore, the information on the whole genome of the SFTS virus (SFTSV) is still limited. This study demonstrates a nearly whole genome of the SFTSV identified in Osaka in 2017 and 2018 by next-generation sequencing (NGS). The evolutionary lineage of two genotypes, C5 and J1, was identified in Osaka. The first case in Osaka belongs to suspect reassortment (L:C5, M:C5, S:C4), the other is genotype J1 (L: J1, M: J1, S: J1) according to the classification by a Japanese group. C5 was identified in China, indicating that C5 identified in this study may be transmitted by birds between China and Japan. This study revealed that different SFTSV genotypes were distributed in two local areas, suggesting the separate or focal transmission patterns in Osaka.

Chimeric flavivirus enables evaluation of antibodies against dengue virus envelope protein in vitro and in vivo

In a secondary dengue virus (DENV) infection, the presence of non-neutralizing antibodies (Abs), developed during a previous infection with a different DENV serotype, is thought to worsen clinical outcomes by enhancing viral production. This phenomenon is called antibody-dependent enhancement (ADE) of infection, and it has delayed the development of therapeutic Abs and vaccines against DENV, as they must be evaluated for the potential to induce ADE. Unfortunately, limited replication of DENV clinical isolates in vitro and in experimental animals hinders this evaluation process. We have, therefore, constructed a recombinant chimeric flavivirus (DV2ChimV), which carries premembrane (prM) and envelope (E) genes of type 2 DENV (DENV-2) R05-624 clinical (Thai) isolate in a backbone of Japanese encephalitis virus (Nakayama strain). DENV E-protein is the most important viral target, not only for neutralizing Abs, but also for infection-enhancing Abs. In contrast to DENV-2 R05-624, DV2ChimV replicated efficiently in cultured mammalian cells and was lethal in interferon-α/β–γ-receptor double-knockout mice. With DV2ChimV, we were able to perform neutralization assays, in vitro and in vivo ADE assays, and in vivo protection assays. These results suggest that the chimeric virus is a powerful tool for evaluation of Abs against DENV.

Fully Human Monoclonal Antibodies Effectively Neutralizing Botulinum Neurotoxin Serotype B

Botulinum neurotoxin (BoNT) is the most potent natural toxin known. Of the seven BoNT serotypes (A to G), types A, B, E, and F cause human botulism. Treatment of human botulism requires the development of effective toxin-neutralizing antibodies without side effects such as serum sickness and anaphylaxis. In this study, we generated fully human monoclonal antibodies (HuMAbs) against serotype B BoNT (BoNT/B1) using a murine–human chimera fusion partner cell line named SPYMEG. Of these HuMAbs, M2, which specifically binds to the light chain of BoNT/B1, showed neutralization activity in a mouse bioassay (approximately 10 i.p. LD₅₀/100 µg of antibody), and M4, which binds to the C-terminal of heavy chain, showed partial protection. The combination of two HuMAbs, M2 (1.25 µg) and M4 (1.25 µg), was able to completely neutralize BoNT/B1 (80 i.p. LD₅₀) with a potency greater than 80 i.p. LD₅₀/2.5 µg of antibodies, and was effective both prophylactically and therapeutically in the mouse model of botulism. Moreover, this combination showed broad neutralization activity against three type B subtypes, namely BoNT/B1, BoNT/B2, and BoNT/B6. These data demonstrate that the combination of M2 and M4 is promising in terms of a foundation for new human therapeutics for BoNT/B intoxication.

Quantification of a cell-mediated immune response against varicella zoster virus by assessing responder CD4high memory cell proliferation in activated whole blood cultures

BACKGROUND

Herpes zoster (HZ) is caused by reactivation of a latent varicella zoster virus (VZV). The potential to develop HZ increases with age due to waning of memory cell-mediated immunity (CMI), mainly the CD4 response. Therefore, VZV-CD4-memory T cells (CD4-M) count in blood could serve as a barometer for HZ protection. However, direct quantification of these cells is known to be difficult because they are few in number in the blood. We thus developed a method to measure the proliferation level of CD4-M cells responding to VZV antigen in whole blood culture.

METHODS

Blood samples were collected from 32 children (2-15 years old) with or without a history of varicella infection, 18 young adults (28-45 years old), and 80 elderly (50-86 years old) with a history of varicella infection. The elderly group was vaccinated, and blood samples were taken 2 months and 1 year after VZV vaccination. Then, 1 mL of blood was mixed with VZV, diluted 1/10 in medium, and cultured. CD4-M cells were identified and measured by flow cytometry.

RESULTS

There was distinct proliferation of CD3⁺CD4^highCD45RA^-RO⁺ (CD4^high-M) cells specific to VZV antigen at day 9. The majority of CD4^high-M cells had the effector memory phenotype CCR7^- and was granzyme B-positive. CD4^high-M cells were detected in blood culture from varicella-immune but not varicella-non-immune children. Meanwhile, a higher level of CD4^high-M proliferation was observed in young adults than in the elderly. The CD4^high-M proliferation level was boosted 2 months after VZV vaccination and maintained for at least 1 year in the elderly.

CONCLUSION

Quantifying VZV responder CD4^high -M cell proliferation is a convenient way to measure VZV CMI using small blood volumes. Our method can be applied to measure VZV vaccine-induced CMI in the elderly. Clinical study registry numbers: (www.clinicaltrials.jp) 173532 and 183985.

In vitro antiviral activity of spirotetronate compounds against dengue virus serotype 2

Spirotetronate compounds are polyketide secondary metabolites with diverse biological functions, such as antibacterial, antitumor and antiviral activities. Three pure spirotetronate compounds (2EPS-A, -B, -C) isolated from Actinomadura strain 2EPS showed inhibitory activity against dengue virus serotype 2 (DENV-2). 2EPS-A, -B and -C demonstrated the LC₅₀ values of 11.6, 27.5 and 12.0 μg/ml, respectively, in a test of cytotoxicity to Vero cells. The least cytotoxic, 2EPS-B, was further analyzed for its impact on viral propagation in a cell-based replication assay. At a concentration of 6.25 μg/ml, it could reduce the DENV-2 infection in Vero cells by about 94% when cells infected with DENV-2 were exposed to 2EPS-B, whereas direct treatment of DENV-2 with 2EPS-B at the same concentration prior to subsequent infection to Vero cell yielded no inhibition. 2EPS-A, -B an -C showed strong DENV-2 NS2B-NS3 protease inhibition in an in vitro assay, with IC₅₀ values of 1.94 ± 0.18, 1.47 ± 0.15 and 2.51 ± 0.21 μg/ml, respectively. Therefore, the spirotetronate compounds appear to prevent viral replication and viral assembly by inhibition of the viral protease.

Protective effects of in vivo-expressed autotransporters against Bordetella pertussis infection

Bordetella pertussis causes whooping cough, a severe and prolonged respiratory disease that results inhas high morbidity and mortality rates, particularly in developing countries. The number incidence of whooping cough cases is increasing in many countries despite high vaccine coverage. Causes for the re-emergence of the disease include the limited duration of protection conferred by the acellular pertussis vaccines (aP)s and pathogenic adaptations that involve antigenic divergence from vaccine strains. Therefore, current vaccines therefore need to be improved. In the present study, we focused on five autotransporters: namely SphB1, BatB, SphB2, Phg, and Vag8, which were previously found to be expressed by B. bronchiseptica during the course of infection in rats and examined their protective efficiencies as vaccine antigens. The passenger domains of these proteins were produced in recombinant forms and used as antigens. An intranasal murine challenge assay showed that immunization with a mixture of SphB1 and Vag8 (SV) significantly reduced bacterial load in the lower respiratory tract and a combination of aP and SV acts synergistically in effects of conferring protection against B. pertussis infection, implying that these antigens have potential as components to for improvinge th the currently available acellular pertussis vaccine.

Evaluation of the fusion partner cell line SPYMEG for obtaining human monoclonal antibodies against influenza B virus

Influenza B virus has been known to infect humans and other animals, including seals. Vaccination efficacy varies across seasons. Human monoclonal antibodies (mAbs) can be useful for developing novel vaccines, guided by epitope analysis, and can be used therapeutically. Hybridoma technology has been used to make mAbs. Here we evaluated SPYMEG as a fusion partner cell line for human mAb generation specific to influenza B hemagglutinin (HA). SPYMEG is a human/murine myeloma partner cell line that has previously been used to generate human mAbs that recognize the HA of influenza A and B viruses. Peripheral blood mononuclear cells were obtained from 16 volunteers, previously vaccinated with the 2014–2015 trivalent seasonal influenza vaccine, and were fused with SPYMEG to yield hybridomas. The resulting hybridomas were screened for antigen-specific antibody secretion and cloned by limiting dilution. We obtained 32 stable clones secreting anti-influenza B HA human IgG, although most of these clones were obtained from one volunteer (SeaV-29) who had a robust immune response. We conclude that SPYMEG is a good fusion partner cell line, although cloning by limiting dilution may lead to significant loss of hybridomas.

Cystargamide B, a cyclic lipodepsipeptide with protease inhibitory activity from Streptomyces sp

We identified a new cyclic lipodepsipeptide, cystargamide B (1), from the mycelial extract of a Kaempferia galanga rhizome-derived actinomycete strain, Streptomyces sp. PB013. The planar structure was elucidated based on high resolution fast-atom bombardment mass spectrometry (HRFABMS) spectroscopy and one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopic data. The absolute configurations of the constituent amino acids were determined using advanced Marfey's method. Cystargamide B (1) includes rare structural units: a 5-hydroxytryptophan residue and a 2,3-epoxy fatty acid side chain. Notably, cystargamide B (1) inhibited the protease activity of the NS2B/NS3 complex from dengue virus.

Construction of a high-yield dengue virus by replacing nonstructural proteins 3-4B without increasing virulence

Producing virus at high yield is critically important for development of whole virion inactivated vaccines or live attenuated vaccines. Most dengue virus (DENV) clinical isolates, however, replicate at low levels in cultured cells, which limits their use for vaccine development. The present study examined differences between low-replicating DENV clinical isolates and high-replicating laboratory strains with the aim of engineering high-yield DENV clinical isolates. Construction of a series of recombinant chimeric viruses derived from a high-replicating laboratory DENV type 4 (DENV-4) H241 strain and a clinical isolate revealed that the NS3-NS4B region of H241 conferred a replication advantage in cultured cells. Furthermore, northern blot analysis revealed that this advantage was due to more efficient synthesis of viral RNA. Importantly, replacement of the NS3-NS4B region of H241 did not increase virulence in mice, suggesting that viral production can be increased safely. This study provided information that will facilitate engineering of safe and high-yield viruses that can be used for vaccine development.

Neutralizing activities against seasonal influenza viruses in human intravenous immunoglobulin

Influenza viruses A/H1N1, A/H3N2, and B are known seasonal viruses that undergo annual mutation. Intravenous immunoglobulin (IVIG) contains anti-seasonal influenza virus globulins. Although the virus-neutralizing (VN) titer is an indicator of protective antibodies, changes in this titer over extended time periods have yet to be examined. In this study, variations in hemagglutination inhibition (HI) and VN titers against seasonal influenza viruses in IVIG lots over extended time periods were examined. In addition, the importance of monitoring the reactivity of IVIG against seasonal influenza viruses with varying antigenicity was evaluated. A/H1N1, A/H3N2, and B influenza virus strains and IVIG lots manufactured from 1999 to 2014 were examined. The HI titer was measured by standard methods. The VN titer was measured using a micro-focus method. IVIG exhibited significant HI and VN titers against all investigated strains. Our results suggest that the donor population maintains both specific and cross-reactive antibodies against seasonal influenza viruses, except in cases of pandemic viruses, despite major antigen changes. The titers against seasonal influenza vaccine strains, including past strains, were stable over short time periods but increased slowly over time.

A Broadly Reactive Human Anti-hemagglutinin Stem Monoclonal Antibody That Inhibits Influenza A Virus Particle Release

Many broadly reactive human monoclonal antibodies against the hemagglutinin (HA) stem of influenza A virus have been developed for therapeutic applications. These antibodies typically inhibit viral entry steps, especially the HA conformational change that is required for membrane fusion. To better understand the mechanisms by which such antibodies inhibit viral replication, we established broadly reactive human anti-HA stem antibodies and determined the properties of these antibodies by examining their reactivity with 18 subtypes of HA, evaluating their in vivo protective efficacy, identifying their epitopes, and characterizing their inhibitory mechanisms. Among the eight human monoclonal antibodies we generated, which recognized at least 3 subtypes of the soluble HA antigens tested, clone S9-1-10/5-1 reacted with 18 subtypes of HA and protected mice from lethal infection with H1N1pdm09, H3N2, H5N1, and H7N9 viruses. This antibody recognized the HA2 helix A in the HA stem, and inhibited virus particle release from infected cells but did not block viral entry completely. These results show that broadly reactive human anti-HA stem antibodies can exhibit protective efficacy by inhibiting virus particle release. These findings expand our knowledge of the mechanisms by which broadly reactive stem-targeting antibodies inhibit viral replication and provide valuable information for universal vaccine development.

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A broadly mouse-protective anti-HA stem antibody, S9-1-10/5-1, was isolated.

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S9-1-10/5-1 mainly inhibited virus release rather than virus entry.

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S9-1-10/5-1 tethers virions via crosslinking HA molecules between neighboring virions.

Broadly reactive human monoclonal antibodies against the influenza HA stem have received attention because of their potential utility against multiple HA subtypes. Some of these antibodies inhibit virus entry and/or protect mice via antibody-dependent cellular cytotoxicity. Here, we identified a human monoclonal antibody that suppresses virus propagation in vitro and in vivo by primarily inhibiting virus particle release. This finding provides another inhibitory mechanism of action for the anti-HA stem antibodies, indicating that the anti-HA stem antibodies could be potent anti-virals due to their pluripotency.

Neutralizing activities of human immunoglobulin derived from donors in Japan against mosquito-borne flaviviruses, Japanese encephalitis virus, West Nile virus, and dengue virus

Japanese encephalitis virus (JEV), West Nile virus (WNV), and dengue virus (DenV) are causal agents of Japanese encephalitis, West Nile fever, and dengue fever, respectively. JEV is considered to be indigenized and widespread in Japan, whereas WNV and DenV are not indigenized in Japan. Globulin products seem to reflect the status of the donor population according to antivirus neutralization activity. However, the anti-JEV, -WNV, and -DenV neutralization activities of globulin products derived from donors in Japan have not been clarified. Furthermore, potential candidates for the development of an effective immunotherapeutic drug for encephalitis caused by JEV, WNV, or DenV have also not been identified. Therefore, the aim of this study was to determine the overall status of the donor population in Japan based on globulin products by evaluating anti-JEV, -WNV, and -DenV neutralizing activities of intravenous immunoglobulin. Overall, intravenous immunoglobulin products showed stable neutralizing activity against JEV but showed no or only weak activity against WNV or DenV. These results suggest that the epidemiological level against WNV and DenV in the donor population of Japan is still low, suggesting that these viruses are not yet indigenized. In addition, JEV vaccinations and/or infections in the donor population do not induce a cross-reactive antibody against WNV.

Genetic characterization of highly pathogenic avian influenza H5N1 viruses isolated from naturally infected pigeons in Egypt

Avian influenza viruses impose serious public health burdens with significant mortality and morbidity not only in poultry but also in humans. While poultry susceptibility to avian influenza virus infection is well characterized, pigeons have been thought to have low susceptibility to these viruses. However, recent studies reported natural pigeon infections with highly pathogenic avian influenza H5N1 viruses. In Egypt, which is one of the H5N1 endemic areas for birds, pigeons are raised in towers built on farms in backyards and on house roofs, providing a potential risk for virus transmission from pigeons to humans. In this study, we performed genetic analysis of two H5N1 virus strains that were isolated from naturally infected pigeons in Egypt. Genetic and phylogenetic analyses showed that these viruses originated from Egyptian H5N1 viruses that were circulating in chickens or ducks. Several unique mutations, not reported before in any Egyptian isolates, were detected in the internal genes (i.e., polymerase residues PB1-V3D, PB1-K363R, PA-A369V, and PA-V602I; nucleoprotein residue NP-R38K; and nonstructural protein residues NS1-D120N and NS2-F55C). Our findings suggested that pigeons are naturally infected with H5N1 virus and can be a potential reservoir for transmission to humans, and showed the importance of genetic analysis of H5N1 internal genes.

Selective Killing of HIV-Infected Cells by Liposomes Composed of dimyristoylphosphatidylcholine/phosphatidylserine/cholesterol

We have previously shown that liposomes containing fragment A of diphtheria toxin, which were prepared by the detergent-dialysis method with egg phosphatidylcholine, phosphatidylserine and cholesterol, possess a selective killing activity against human immunodeficiency virus (HIV)-1-infected cells, but not against uninfected cells (Ikuta et al., 1987). Since the liposomes were found to be unstable in human plasma in vitro, we prepared improved liposomes by the extrusion method with dimyristoylphosphatidylcholine instead of egg phosphatidylcholine. These liposomes were found to be very stable in human plasma, and also possessed the selective killing activity against HIV-1-infected cells. In addition, it was found that the fragment A in the liposomes was not necessary for the selective cell killing activity. The cell killing activity and selectivity of HIV-1-infected cells of the liposomes were remarkably affected by cholesterol content and the acyl chain length of the saturated fatty acid of phosphatidylcholines. These data suggest that membranes of liposomes can interact specifically with HIV-1-infected cells, but not with uninfected cells, resulting in the inhibition of cell proliferation.

Characterization of two anti-dengue human monoclonal antibodies prepared from PBMCs of patients with dengue illness in Thailand

The global spread of the four dengue virus (DENV) serotypes (dengue-1 to -4) has made this virus a major and growing public health concern. Generally, pre-existing neutralizing antibodies derived from primary infection play a significant role in protecting against subsequent infection with the same serotype. By contrast, these pre-existing antibodies are believed to mediate a non-protective response to subsequent heterotypic DENV infections, leading to the onset of dengue illness. In this study, two monoclonal antibodies prepared by using peripheral blood mononuclear cells (PBMCs) from patients with dengue fever were characterized. Epitope mapping revealed that amino acid residues 254-278 in domain II of the viral envelope protein E were the target region of these antibodies. A database search revealed that certain sequences in this epitope region showed high conservation among the four serotypes of DENV. These two human monoclonal antibodies could neutralize DENV-2,-4 more effectively than DENV-1,-3. The amino acid sequences could not explain this difference in neutralizing activity. However, the 3D structure results showed that amino acid 274 could be the critical residue for the difference in neutralization. These results may provide basic information for the development of a dengue vaccine.

Capture of dengue viruses using antibody-integrated graphite-encapsulated magnetic beads produced using gas plasma technology

Despite significant advances in medicine, global health is threatened by emerging infectious diseases caused by a number of viruses. Dengue virus (DENV) is a mosquito-borne virus, which can be transmitted to humans via mosquito vectors. Previously, the Ministry of Health, Labour and Welfare in Japan reported the country's first domestically acquired case of dengue fever for almost 70 years. To address this issue, it is important to develop novel technologies for the sensitive detection of DENV. The present study reported on the development of plasma-functionalized, graphite-encapsulated magnetic nanoparticles (GrMNPs) conjugated with anti-DENV antibody for DENV capture. Radiofrequency wave-excited inductively-coupled Ar and ammonia gas plasmas were used to introduce amino groups onto the surface of the GrMNPs. The GrMNPs were then conjugated with an antibody against DENV, and the antibody-integrated magnetic beads were assessed for their ability to capture DENV. Beads incubated in a cell culture medium of DENV-infected mosquito cells were separated from the supernatant by applying a magnetic field and were then washed. The adsorption of DENV serotypes 1–4 onto the beads was confirmed using reverse transcription-polymerase chain reaction, which detected the presence of DENV genomic RNA on the GrMNPs. The methodology described in the present study, which employed the plasma-functionalization of GrMNPs to enable antibody-integration, represents a significant improvement in the detection of DENV.

Capturing and concentrating adenovirus using magnetic anionic nanobeads

We recently demonstrated how various enveloped viruses can be efficiently concentrated using magnetic beads coated with an anionic polymer, poly(methyl vinyl ether-maleic anhydrate). However, the exact mechanism of interaction between the virus particles and anionic beads remains unclear. To further investigate whether these magnetic anionic beads specifically bind to the viral envelope, we examined their potential interaction with a nonenveloped virus (adenovirus). The beads were incubated with either adenovirus-infected cell culture medium or nasal aspirates from adenovirus-infected individuals and then separated from the supernatant by applying a magnetic field. After thoroughly washing the beads, adsorption of adenovirus was confirmed by a variety of techniques, including immunochromatography, polymerase chain reaction, Western blotting, and cell culture infection assays. These detection methods positively identified the hexon and penton capsid proteins of adenovirus along with the viral genome on the magnetic beads. Furthermore, various types of adenovirus including Types 5, 6, 11, 19, and 41 were captured using the magnetic bead procedure. Our bead capture method was also found to increase the sensitivity of viral detection. Adenovirus below the detectable limit for immunochromatography was efficiently concentrated using the magnetic bead procedure, allowing the virus to be successfully detected using this methodology. Moreover, these findings clearly demonstrate that a viral envelope is not required for binding to the anionic magnetic beads. Taken together, our results show that this capture procedure increases the sensitivity of detection of adenovirus and would, therefore, be a valuable tool for analyzing both clinical and experimental samples.

Novel Polymerase Gene Mutations for Human Adaptation in Clinical Isolates of Avian H5N1 Influenza Viruses

A major determinant in the change of the avian influenza virus host range to humans is the E627K substitution in the PB2 polymerase protein. However, the polymerase activity of avian influenza viruses with a single PB2-E627K mutation is still lower than that of seasonal human influenza viruses, implying that avian viruses require polymerase mutations in addition to PB2-627K for human adaptation. Here, we used a database search of H5N1 clade 2.2.1 virus sequences with the PB2-627K mutation to identify other polymerase adaptation mutations that have been selected in infected patients. Several of the mutations identified acted cooperatively with PB2-627K to increase viral growth in human airway epithelial cells and mouse lungs. These mutations were in multiple domains of the polymerase complex other than the PB2-627 domain, highlighting a complicated avian-to-human adaptation pathway of avian influenza viruses. Thus, H5N1 viruses could rapidly acquire multiple polymerase mutations that function cooperatively with PB2-627K in infected patients for optimal human adaptation.

Avian influenza (AI) virus H5N1 subtype strains have been sporadically transmitted to humans with high mortality (>60%), presenting a serious global health threat. In particular, 63% of recent human H5N1 infection cases worldwide have been reported in Egypt, which is now regarded as a hot spot for H5N1 virus evolution. H5N1 clade 2.2.1 viruses are unique to Egypt and probably have the greatest evolutionary potential for adaptation from avian to human hosts. Here, using a comprehensive database approach, we identified various novel polymerase mutations in clade 2.2.1 virus strains, isolated from patients, that enabled enhanced viral replication in both human airway epithelial cells and mouse lungs. Interestingly, the mutations identified acted cooperatively with the PB2-E627K mutation, the most well-known human adaptation mutation, to produce a further increase in viral replication in human hosts. These results provide the first broad-spectrum data on the polymerase characteristics of AI viruses that have been selected in infected patients, and also give new insight into the human adaptation mechanisms of AI viruses.

Antibody with an engineered Fc region as a therapeutic agent against dengue virus infection

Antibody-dependent enhancement (ADE) of dengue virus (DENV) infectivity is thought to play a crucial role in severe dengue disease. It occurs when pre-existing sub-neutralizing anti-DENV antibody (Ab) produced from a primary infection encounters a DENV serotype different from that of the initial infection and forms immune complexes, which enable the efficient infection of Fcγ receptor-bearing cells. However, the exact role played by Abs during a secondary infection of patients remains unknown. We previously obtained a broadly cross-reactive neutralizing IgG1 human monoclonal anti-DENV envelope (E) Ab (HuMAb) D23-1G7C2-IgG1 from a DENV-infected patient; however, D23-1G7C2-IgG1 had ADE activity. With the aim of being able to reduce the ADE activity, we exchanged the Fc region of D23-1G7C2 to generate Abs bearing each of the three other IgG subclasses (IgG2-4). In addition, N297A, a mutation known to reduce the affinity of the IgG1 Fc region for Fcγ receptors, was introduced into D23-1G7C2-IgG1. Swapping D23-1G7C2-IgG1 to IgG2 or IgG4 subclasses reduced ADE activity in FcγRI and FcγRII-bearing THP-1 cells. By contrast, in FcγRII-bearing K562 cells, the change to IgG2 increased ADE activity. Introducing the N297A mutation into D23-1G7C2-IgG1 resulted in a marked reduction in ADE activity in both cell types. Compared to D23-1G7C2-IgG1, D23-1G7C2-IgG1-N297A was less protective in IFN-α/β/γ receptor knockout mice infected with a lethal dose of recombinant chimeric DENV, carrying prME of DENV-2 in Japanese encephalitis virus (80% vs. 40% survival, respectively). These observations provide valuable information regarding the use of recombinant Abs as therapeutics.

Avian Influenza Virus Infection of Immortalized Human Respiratory Epithelial Cells Depends upon a Delicate Balance between Hemagglutinin Acid Stability and Endosomal pH

The highly pathogenic avian influenza (AI) virus, H5N1, is a serious threat to public health worldwide. Both the currently circulating H5N1 and previously circulating AI viruses recognize avian-type receptors; however, only the H5N1 is highly infectious and virulent in humans. The mechanism(s) underlying this difference in infectivity remains unclear. The aim of this study was to clarify the mechanisms responsible for the difference in infectivity between the current and previously circulating strains. Primary human small airway epithelial cells (SAECs) were transformed with the SV40 large T-antigen to establish a series of clones (SAEC-Ts). These clones were then used to test the infectivity of AI strains. Human SAEC-Ts could be broadly categorized into two different types based on their susceptibility (high or low) to the viruses. SAEC-T clones were poorly susceptible to previously circulating AI but were completely susceptible to the currently circulating H5N1. The hemagglutinin (HA) of the current H5N1 virus showed greater membrane fusion activity at higher pH levels than that of previous AI viruses, resulting in broader cell tropism. Moreover, the endosomal pH was lower in high susceptibility SAEC-T clones than that in low susceptibility SAEC-T clones. Taken together, the results of this study suggest that the infectivity of AI viruses, including H5N1, depends upon a delicate balance between the acid sensitivity of the viral HA and the pH within the endosomes of the target cell. Thus, one of the mechanisms underlying H5N1 pathogenesis in humans relies on its ability to fuse efficiently with the endosomes in human airway epithelial cells.

Sequence variation of dengue type 2 virus isolated from clinical cases in Thailand

Dengue fever (DF) and dengue hemorrhagic fever (DHF) are caused by mosquito-borne dengue virus (DENV) infection leading to death in tropical and subtropical countries. In Thailand, all 4 serotypes of DENV are circulating. The most severe cases of DF and DHF are primarily introduced by secondary infections. Epidemiological studies have demonstrated that approximately 20% of the primary infection cases were caused by DENV-1 and -3, while the cases of DENV-2 or -4 accounted for less than 3%. For this reason, DENV-2 and -4 from primary infections have not been well studied. In this study, the sequence diversity of the envelope gene of 8 DENV-2 clinical isolates from primary/secondary infections was analyzed. DENV-2 from primary infections were highly heterogeneous in individual patients, whereas those from secondary infections were homogeneous. Phylogenetic analysis demonstrated that the heterogeneous population of DENV-2 from primary infections was composed of closely related quasispecies. Homogenous DENV-2 could be derived from selection of a particular viral population in secondary infections. The degree of sequence diversity of DENV-2 varied, and thus quasispecies may be involved in the progression of DENV infection.

A novel immunochromatographic system for easy-to-use detection of group 1 avian influenza viruses with acquired human-type receptor binding specificity

A switch of viral hemagglutinin receptor binding specificity from bird-type α2,3- to human-type α2,6-linked sialic acid is necessary for an avian influenza virus to become a pandemic virus. In this study, an easy-to-use strip test to detect receptor binding specificity of influenza virus was developed. A biotinylated anti-hemagglutinin antibody that bound a broad range of group 1 influenza A viruses and latex-conjugated α2,3 (blue) and α2,6 (red) sialylglycopolymers were used in an immunochromatographic strip test, with avidin and lectin immobilized on a nitrocellulose membrane at test and control lines, respectively. Accumulation of a sialylglycopolymer–virus–antibody complex at the test line was visualized by eye. The strip test could be completed in 30 min and did not require special equipment or skills, thereby avoiding some disadvantages of current methods for analyzing receptor binding specificity of influenza virus. The strip test could detect the receptor binding specificity of a wide range of influenza viruses, as well as small increases in the binding affinity of variant H5N1 viruses to α2,6 sialylglycans at viral titers >128 hemagglutination units. The strip test results were in agreement with those of ELISA virus binding assays, with correlations >0.95. In conclusion, the immunochromatographic strip test developed in this study should be useful for monitoring potential changes in the receptor binding specificity of group 1 influenza A viruses in the field.

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A novel immunochromatographic strip test system was developed.

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The strip test was developed to detect influenza virus receptor binding specificity.

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The strip test was applicable to a broad range of group 1 influenza A viruses.

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The strip detected faint increases in human-type specificity of variant H5N1 viruses.

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The system could be applied for easy monitoring the viral pandemic potential.

A human monoclonal antibody derived from a vaccinated volunteer recognizes heterosubtypically a novel epitope on the hemagglutinin globular head of H1 and H9 influenza A viruses

Most neutralizing antibodies elicited during influenza virus infection or by vaccination have a narrow spectrum because they usually target variable epitopes in the globular head region of hemagglutinin (HA). In this study, we describe a human monoclonal antibody (HuMAb), 5D7, that was prepared from the peripheral blood lymphocytes of a vaccinated volunteer using the fusion method. The HuMAb heterosubtypically neutralizes group 1 influenza A viruses, including seasonal H1N1, 2009 pandemic H1N1 (H1N1pdm) and avian H9N2, with a strong hemagglutinin inhibition activity. Selection of an escape mutant showed that the HuMAb targets a novel conformational epitope that is located in the HA head region but is distinct from the receptor binding site. Furthermore, Phe114Ile substitution in the epitope made the HA unrecognizable by the HuMAb. Amino acid residues in the predicted epitope region are also highly conserved in the HAs of H1N1 and H9N2. The HuMAb reported here may be a potential candidate for the development of therapeutic/prophylactic antibodies against H1 and H9 influenza viruses.

Chikungunya virus was isolated in Thailand, 2010

Chikungunya fever (CHIKF) is an acute febrile illness caused by a mosquito-borne alphavirus, chikungunya virus (CHIKV). This disease re-emerged in Kenya in 2004, and spread to the countries in and around the Indian Ocean. The re-emerging epidemics rapidly spread to regions like India and Southeast Asia, and it was subsequently identified in Europe in 2007, probably as a result of importation of chikungunya cases. On the one hand, chikungunya is one of the neglected diseases and has only attracted strong attention during large outbreaks. In 2008–2009, there was a major outbreak of chikungunya fever in Thailand, resulting in the highest number of infections in any country in the region. However, no update of CHIKV circulating in Thailand has been published since 2009. In this study, we examined the viral growth kinetics and sequences of the structural genes derived from CHIKV clinical isolates obtained from the serum specimens of CHIKF-suspected patients in Central Thailand in 2010. We identified the CHIKV harboring two mutations E1-A226V and E2-I211T, indicating that the East, Central, and South African lineage of CHIKV was continuously circulating as an indigenous population in Thailand.

Monoclonal antibody targeting chikungunya virus envelope 1 protein inhibits virus release

Chikungunya virus (CHIKV) causes an acute clinical illness characterized by sudden high fever, intense joint pain, and skin rash. Recent outbreaks of chikungunya disease in Africa and Asia are a major public health concern; however, there is currently no effective licensed vaccine or specific treatment. This study reported the development of a mouse monoclonal antibody (MAb), CK47, which recognizes domain III within the viral envelope 1 protein and inhibited the viral release process, thereby preventing the production of progeny virus. The MAb had no effect on virus entry and replication processes. Thus, CK47 may be a useful tool for studying the mechanisms underlying CHIKV release and may show potential as a therapeutic agent.

A highly conserved region between amino acids 221 and 266 of dengue virus non-structural protein 1 is a major epitope region in infected patients

The immune response to dengue virus (DENV) infection generates high levels of antibodies (Abs) against the DENV non-structural protein 1 (NS1), particularly in cases of secondary infection. Therefore, anti-NS1 Abs may play a role in severe dengue infections, possibly by interacting (directly or indirectly) with host factors or regulating virus production. If it does play a role, NS1 may contain epitopes that mimic those epitopes of host molecules. Previous attempts to map immunogenic regions within DENV-NS1 were undertaken using mouse monoclonal Abs (MAbs). The aim of this study was to characterize the epitope regions of nine anti-NS1 human monoclonal Abs (HuMAbs) derived from six patients secondarily infected with DENV-2. These anti-NS1 HuMAbs were cross-reactive with DENV-1, -2, and -3 but not DENV-4. All HuMAbs bound a common epitope region located between amino acids 221 and 266 of NS1. This study is the first report to map a DENV-NS1 epitope region using anti-DENV MAbs derived from patients.

Impact of amino acid substitutions in the V2 and C2 regions of human immunodeficiency virus type 1 CRF01_AE envelope glycoprotein gp120 on viral neutralization susceptibility to broadly neutralizing antibodies specific for the CD4 binding site

Background

The CD4 binding site (CD4bs) of envelope glycoprotein (Env) gp120 is a functionally conserved, important target of anti-human immunodeficiency virus type 1 (HIV-1) neutralizing antibodies. Two neutralizing human monoclonal antibodies, IgG1 b12 (b12) and VRC01, are broadly reactive neutralizing antibodies which recognize conformational epitopes that overlap the CD4bs of Env gp120; however, many CRF01_AE viruses are resistant to neutralization mediated by these antibodies. We examined the mechanism underlying the b12 resistance of the viruses using CRF01_AE Env (AE-Env)-recombinant viruses in this study.

Results

Our results showed that an amino acid substitution at position 185 in the V2 region of gp120 played a crucial role in regulating the b12 susceptibility of AE-Env-recombinant viruses by cooperating with 2 previously reported potential N-linked glycosylation (PNLG) sites at positions 186 (N186) and 197 (N197) in the V2 and C2 regions of Env gp120. The amino acid residue at position 185 and 2 PNLG sites were responsible for the b12 resistance of 21 of 23 (>91%) AE-Env clones tested. Namely, the introduction of aspartic acid at position 185 (D185) conferred b12 susceptibility of 12 resistant AE-Env clones in the absence of N186 and/or N197, while the introduction of glycine at position 185 (G185) reduced the b12 susceptibility of 9 susceptible AE-Env clones in the absence of N186 and/or N197. In addition, these amino acid mutations altered the VRC01 susceptibility of many AE-Env clones.

Conclusions

We propose that the V2 and C2 regions of AE-Env gp120 contain the major determinants of viral resistance to CD4bs antibodies. CRF01_AE is a major circulating recombinant form of HIV-1 prevalent in Southeast Asia. Our data may provide important information to understand the molecular mechanism regulating the neutralization susceptibility of CRF01_AE viruses to CD4bs antibodies.

Low levels of antibody-dependent enhancement in vitro using viruses and plasma from dengue patients

Background

The majority of dengue patients infected with any serotype of dengue virus (DENV) are asymptomatic, but the remainder may develop a wide spectrum of clinical symptoms, ranging from mild dengue fever (DF) to severe dengue hemorrhagic fever (DHF). Severe cases occur more often in patients who experience a secondary infection with a different virus serotype. A phenomenon called antibody-dependent enhancement (ADE) has been proposed to explain the onset of these severe cases, but the exact mechanism of ADE remains unclear.

Methodology/Principal Finding

Virus neutralization and ADE assays were performed using ultracentrifugation supernatants of acute-phase sera from patients with secondary infections or human monoclonal antibodies (HuMAbs) as anti-DENV antibodies. Virus sources included infectious serum-derived viruses from the ultracentrifugation precipitates, laboratory-culture adapted DENV, or recombinant DENVs derived from patient sera. In contrast to the high levels of ADE observed with laboratory virus strains, low ADE was observed with autologous patient-derived viruses, when patient sera were used to provide the antibody component in the ADE assays. Similar results were obtained using samples from DF and DHF patients. Recombinant-viruses derived from DHF patients showed only minor differences in neutralization and ADE activity in the presence of HuMAbs or plasma derived from the same DHF patient.

Conclusion/Significance

Serum or plasma taken from patients during the acute phase of a secondary infection showed high levels of ADE, but no neutralization activity, when assayed in the presence of laboratory-adapted virus strains. By contrast, serum or plasma from the same patient showed high levels of neutralization activity but failed to induce significant ADE when the assays were performed with autologous virus. These results demonstrate the significance of the virus source when measuring ADE. They also suggest that repeated passage of DENV in cell culture has endowed it with the capacity to induce high levels of ADE.

Molecular characterization of Clostridium botulinum isolates from foodborne outbreaks in Thailand, 2010

Background

Thailand has had several foodborne outbreaks of botulism, one of the biggest being in 2006 when laboratory investigations identified the etiologic agent as Clostridium botulinum type A. Identification of the etiologic agent from outbreak samples is laborious using conventional microbiological methods and the neurotoxin mouse bioassay. Advances in molecular techniques have added enormous information regarding the etiology of outbreaks and characterization of isolates. We applied these methods in three outbreaks of botulism in Thailand in 2010.

Methodology/Principal Findings

A total of 19 cases were involved (seven each in Lampang and Saraburi and five in Maehongson provinces). The first outbreak in Lampang province in April 2010 was associated with C. botulinum type F, which was detected by conventional methods. Outbreaks in Saraburi and Maehongson provinces occurred in May and December were due to C. botulinum type A1(B) and B that were identified by conventional methods and molecular techniques, respectively. The result of phylogenetic sequence analysis showed that C. botulinum type A1(B) strain Saraburi 2010 was close to strain Iwate 2007. Molecular analysis of the third outbreak in Maehongson province showed C. botulinum type B8, which was different from B1–B7 subtype. The nontoxic component genes of strain Maehongson 2010 revealed that ha33, ha17 and botR genes were close to strain Okra (B1) while ha70 and ntnh genes were close to strain 111 (B2).

Conclusion/Significance

This study demonstrates the utility of molecular genotyping of C. botulinum and how it contributes to our understanding the epidemiology and variation of boNT gene. Thus, the recent botulism outbreaks in Thailand were induced by various C. botulinum types.

Preparation of Monoclonal Antibodies Cross-Reactive with Orthopoxviruses and Their Application for Direct Immunofluorescence Test

Variola virus (smallpox virus), vaccinia virus (VV), cowpox virus (CPV) and ectromelia virus (EV) belong to the genus Orthopoxvirus of the family Poxviridae. To establish the possible diagnosis for smallpox infection, monoclonal antibodies (MAbs) against VV and CPV were produced. The cross-reactivity of seven MAbs with cells infected with various strains of the orthopoxviruses (CPV, VV and EV) was confirmed by an immunofluorescence (IF) test and other immunological analyses. Four and three MAbs reacted with the common antigen of all poxviruses (probably NP antigen) and the antigen involved in neutralization, respectively. We developed the IF test using these MAbs. The direct IF test required only 45 min to perform. Smallpox infection is now eradicated, but it is important to prepare for the diagnosis of smallpox in an emergency. The direct IF assay using MAbs cross-reactive with orthopoxviruses is rapid, simple, specific, applicable for multiple samples, and will make it possible to screen for and detect orthopoxviruses that include variola virus with tissue impression smears from skin lesions in most laboratories or institutes.

Immunization of rabbits with synthetic peptides derived from a highly conserved β-sheet epitope region underneath the receptor binding site of influenza A virus

BACKGROUND

There is increasing concern about the speed with which health care providers can administer prophylaxis and treatment in an influenza pandemic. Generally, it takes several months to manufacture an influenza vaccine by propagation of the virus in chicken eggs or cultured cells. Newer, faster protocols for the production of vaccines that induce broad-spectrum immunity are therefore highly desirable. We previously developed human monoclonal antibody B-1 that shows broadly neutralizing activity against influenza A virus H3N2. B-1 recognizes an epitope region that includes an antiparallel β-sheet structure underneath the receptor binding site of influenza hemagglutinin (HA). In this study, the efficacy of a synthetic peptide vaccine derived from this epitope region against influenza A was evaluated.

MATERIALS AND METHODS

Two peptides were synthesized, the upper and lower peptides. These peptides comprise amino acid residues 167-187 and 225-241, respectively, of the B-1 epitope region of HA, which is involved in forming the β-sheet structure. Both peptides were then coupled to keyhole limpet hemocyanin, and the peptides, alone or in combination, were used to immunize rabbits. The resulting antibody responses were examined by enzyme-linked immunosorbent assay. The upper peptide, but not the lower peptide, elicited antibodies that were reactive to HA. Interestingly, the use of both peptides together could elicit antibodies with a higher reactivity to HA than either peptide alone. The antibodies were found to react to HA at the N-terminus of the upper peptide, which is exposed at the surface of trimeric HA on influenza virions.

DISCUSSION

The higher production of HA-reactive antibodies following immunization with both peptides suggests that the upper peptide forms the effective epitope structure in the binding state, and the lower peptide enhances the production of HA antibodies. This study could be the first step towards the development of pandemic viral vaccines that can be produced within short time periods.

Origin and distribution of divergent dengue virus: novel database construction and phylogenetic analyses

Dengue virus (DENV), a mosquito-borne agent that exists as four serotypes (DENV-1–4), induces dengue illness. DENV has a positive-sense, ssRNA genome of approximately 11 kb that encodes a capsid protein, a premembrane protein and an envelope glycoprotein, in addition to seven nonstructural proteins. These individual genes show sequence variations that can be analyzed phylogenetically to yield several genotypes within each serotype. Here, the sequences of individual DENV genes were collected and used to construct a novel DENV database. This database was then used to characterize the evolution of individual genotypes in several countries. Interestingly, the database provided evidence for recombination between two or three different genotypes to yield new genotypes. This novel database will be available on the internet and is expected to be highly useful for dengue genetic studies, including phylogenetic analyses.

microRNA-18a induces apoptosis in colon cancer cells via the autophagolysosomal degradation of oncogenic heterogeneous nuclear ribonucleoprotein A1

It is well known that microRNAs (miRs) are abnormally expressed in various cancers and target the messenger RNAs (mRNAs) of cancer-associated genes. While (miRs) are abnormally expressed in various cancers, whether miRs directly target oncogenic proteins is unknown. The present study investigated the inhibitory effects of miR-18a on colon cancer progression, which was considered to be mediated through its direct binding and degradation of heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1). An MTT assay and xenograft model demonstrated that the transfection of miR-18a induced apoptosis in SW620 cells. A binding assay revealed direct binding between miR-18a and hnRNP A1 in the cytoplasm of SW620 cells, which inhibited the oncogenic functions of hnRNP A1. A competitor RNA, which included the complementary sequence of the region of the miR-18a-hnRNP A1 binding site, repressed the effects of miR-18a on the induction of cancer cell apoptosis. In vitro single and in vivo double isotope assays demonstrated that miR-18a induced the degradation of hnRNP A1. An immunocytochemical study of hnRNP A1 and LC3-II and the inhibition of autophagy by 3-methyladenine and ATG7, p62 and BAG3 siRNA showed that miR-18a and hnRNP A1 formed a complex that was degraded through the autophagolysosomal pathway. This is the first report showing a novel function of a miR in the autophagolysosomal degradation of an oncogenic protein resulting from the creation of a complex consisting of the miR and a RNA-binding protein, which suppressed cancer progression.