Ki Hoon Park

Immunogenicity of a trivalent human papillomavirus L1 DNA-encapsidated, non-replicable baculovirus nanovaccine.

Previously, we developed a non-replicating recombinant baculovirus coated with human endogenous retrovirus envelope protein (AcHERV) for enhanced cellular delivery of human papillomavirus (HPV) 16L1 DNA. Here, we report the immunogenicity of an AcHERV-based multivalent HPV nanovaccine in which the L1 segments of HPV 16, 18, and 58 genes were inserted into a single baculovirus genome of AcHERV. To test whether gene expression levels were affected by the order of HPV L1 gene insertion, we compared the efficacy of bivalent AcHERV vaccines with the HPV 16L1 gene inserted ahead of the 18L1 gene (AcHERV-HP16/18L1) with that of AcHERV with the HPV 18L1 gene inserted ahead of the 16L1 gene (AcHERV-HP18/16L1). Regardless of the order, the bivalent AcHERV DNA vaccines retained the immunogenicity of monovalent AcHERV-HP16L1 and AcHERV-HP18L1 DNA vaccines. Moreover, the immunogenicity of bivalent AcHERV-HP16/18L1 was not significantly different from that of AcHERV-HP18/16L1. In challenge tests, both bivalent vaccines provided complete protection against HPV 16 and 18 pseudotype viruses. Extending these results, we found that a trivalent AcHERV nanovaccine encoding HPV 16L1, 18L1, and 58L1 genes (AcHERV-HP16/18/58L1) provided high levels of humoral and cellular immunogenicity against all three subtypes. Moreover, mice immunized with the trivalent AcHERV-based nanovaccine were protected from challenge with HPV 16, 18, and 58 pseudotype viruses. These results suggest that trivalent AcHERV-HPV16/18/58L1 could serve as a potential prophylactic baculoviral nanovaccine against concurrent infection with HPV 16, 18, and 58.

Sublingual Immunization of Trivalent Human Papillomavirus DNA Vaccine in Baculovirus Nanovector for Protection against Vaginal Challenge

Here, we report the immunogenicity of a sublingually delivered, trivalent human papillomavirus (HPV) DNA vaccine encapsidated in a human endogenous retrovirus (HERV) envelope-coated, nonreplicable, baculovirus nanovector. The HERV envelope-coated, nonreplicable, baculovirus-based DNA vaccine, encoding HPV16L1, -18L1 and -58L1 (AcHERV-triHPV), was constructed and sublingually administered to mice without adjuvant. Following sublingual (SL) administration, AcHERV-triHPV was absorbed and distributed throughout the body. At 15 minutes and 1 day post-dose, the distribution of AcHERV-triHPV to the lung was higher than that to other tissues. At 30 days post-dose, the levels of AcHERV-triHPV had diminished throughout the body. Six weeks after the first of three doses, 1×108 copies of SL AcHERV-triHPV induced HPV type-specific serum IgG and neutralizing antibodies to a degree comparable to that of IM immunization with 1×109 copies. AcHERV-triHPV induced HPV type-specific vaginal IgA titers in a dose-dependent manner. SL immunization with 1×1010 copies of AcHERV-triHPV induced Th1 and Th2 cellular responses comparable to IM immunization with 1×109 copies. Molecular imaging revealed that SL AcHERV-triHPV in mice provided complete protection against vaginal challenge with HPV16, HPV18, and HPV58 pseudoviruses. These results support the potential of SL immunization using multivalent DNA vaccine in baculovirus nanovector for induction of mucosal, systemic, and cellular immune responses.

Comparison of JEV neutralization assay using pseudotyped JEV with the conventional plaque-reduction neutralization test.

We previously reported the development of a neutralization assay system for evaluating Japanese Encephalitis Virus (JEV) neutralizing antibody (NAb) using pseudotyped-JEV (JEV-PV). JEV-PV-based neutralization assay offers several advantages compared with the current standard plaque-reduction neutralization test (PRNT), including simplicity, safety, and speed. To evaluate the suitability of the JEV-PV assay as new replacement neutralization assay, we compared its repeatability, reproducibility, specificity, and correlated its results with those obtained using the PRNT. These analyses showed a close correlation between the results obtained with the JEV-PV assay and the PRNT, using the 50% plaque reduction method as a standard for measuring NAb titers to JEV. The validation results met all analytical acceptance criteria. These results suggest that the JEV-PV assay could serve as a safe and simple method for measuring NAb titer against JEV and could be used as an alternative approach for assaying the potency of JEV neutralization.

A Development of Miniaturized Piezoelectric Actuator System for Mobile Smart Structures

A smart material actuator is required for a smart structure having multifunctional performance. Among the smart material actuators, piezoelectric actuator is known for its excellent large force generation in broad bandwidth in a compact size. However it needs relatively large actuation voltage requiring a bulky hardware system. This study is mainly concerned to develop a self-powered miniaturized piezoelectric actuator driver (MIPAD) controlled by a radio controller for small sized piezoelectric smart structures. It can receive command from other microprocessors or a remote radio controller. We designed a real hardware and it demonstrated good performances even though the driving system was very small. The MIPAD is expected to minimize the weight and size of the piezoelectric actuator system and it can be easily embedded into mobile smart structures.

Piezo‐composite actuated control surface system for flying vehicle

Purpose – The purpose of this paper is to develop lightweight actuators in order to replace conventional hydraulic/pneumatic actuators and to apply the actuation system to a small flying vehicle.Design/methodology/approach – A new type of control surface using a piezo‐composite actuator for a small flying vehicle has been designed and manufactured. The piezo‐composite actuator is composed of a piezoelectric ceramic layer, a carbon/epoxy layer and glass/epoxy layers. Through this, the miniaturization and weight reduction of the actuation systems for flying vehicle can be achieved. A simple model of the control surface has been manufactured and evaluated through experiments.Findings – The performance test results showed that the developed actuator can produce stable angle of attack independent of the applied loading. A radio controller for the actuator was developed to control the motions wirelessly. It was found that the piezo‐composite actuator and its integrated controller system have a possibility to be...

Antiviral activity of Poncirus trifoliata seed extract against oseltamivir-resistant influenza virus

The emergence of oseltamivir-resistant variants of influenza virus has highlighted the necessity for the development of more effective novel antiviral drugs. To date, numerous researchers have focused on developing antiviral drugs using natural resources, such as traditional herbal medicines. Poncirus trifoliata is widely used in oriental medicine as a remedy for gastritis, dysentery, inflammation and digestive ulcers. In this study, we investigated the potential antiviral effect of the Poncirus trifoliata orange seed extract against influenza virus. An ethanol extract of Poncirus trifoliata seeds (PTex) inhibited the activity of influenza viruses, in particular, oseltamivir- resistant strains, in Madin-Darby canine kidney cells. In contrast to oseltamivir, PTex exerted a significant inhibitory effect on the cellular penetration pathway of the virus rather than HA receptor binding. The potent antiviral effect and novel working mechanism of PTex support its further development as an effective natural antiviral drug with a wide spectrum of activity against influenza and oseltamivir-resistant viruses.

Fatigue characteristics of lightweight piezocomposite actuators

This paper is concerned with the fatigue characteristics of LIPCA (LIghtweight Piezo-Composite Actuator) device systems, composed of a piezoelectric ceramic layer and fiber reinforced light composite layers, where the PZT ceramic layer is typically sandwiched by a top fiber layer with a low CTE (coefficient of thermal expansion) and base layers with a high CTE. The advantages of the LIPCA design include the use of lightweight fiber reinforced plastic layers without compromising the generation of a high force and large displacement, and design flexibility in selecting the fiber direction and size of the prepreg layers. In addition, a LIPCA device can be manufactured without adhesive layers since epoxy resin plays role of bonding material. To investigate the degradation of the actuation performance of LIPCAs due to repeated fatigue loading, repeated loading tests up to several million cycles were performed and the actuation displacement for a given excitation voltage measured during the test. The fatigue characteristics were measured using an actuator test system consisting of an actuator-supporting jig, high-voltage actuating power supplier, and non-contact laser measuring system and evaluated.

Compact Biomimetic Structure Systems with LIPCA and Battery Supported Power Control Unit

This paper describes the development of biomimetic structure systems with LIPCA (LIghtweight Piezo-Composite Actuator) and battery supported power control unit. To apply LIPCA as a biomimetic actuator for the control surface of small unmanned air vehicle, a battery supported power control unit was developed, which is composed of a lithium polymer, one step-up converter, four power switching high voltage transistors, on Schmitt triggered comparator, and control logics. A simple RC circuit is used to sample the voltage applied to the LIPCA. H-switch was applied which is composed of the four high voltage transistors to control the voltage or charge and its polarity applied to the LIPCA. From experiments, it was observed that the developed biomimetic adaptronic systems could be constructed with relatively compact and light units and could produce enough displacement and force to be used as a control surface for the elevator and the rudder of a small unmanned vehicle.

Nonlinear performance analysis of LIPCA actuator by using an assumed strain shell element

In the present work, the existing formulation of nine-node shell element based on Hellinger-Reissner principle is expanded for electro-mechanically coupled field analysis. The electro-mechanical coupling effect of the piezoelectric material is introduced to the formulation through the constitutive relation. Based on the formulation, a linear finite element code is constructed and it is validated by several numerical tests. By using the code, linear analysis of LIPCA(LIghtweight Piezoelectric Composite Actuator) is performed to calculate actuation displacement and stress. Moreover, to improve simulation result more accurately, an experimental piezo-strain function of PZT(3203HD, CTS) wafer that is embedded in LIPCA is obtained from measured data and the function is implemented into the code by adopting incremental method. And then, the actuation displacement of LIPCA is recalculated and the result is compared with the measured data.