• Korean Journal of Veterinary Service
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• v.35 no.3
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• pp.169-174
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• 2012

Japanese encephalitis virus (JEV) is one of the main causes of viral encephalitis in human and animals. For over 30 years, a live attenuated JEV vaccine strain has been used in the veterinary field, and it is required to conduct quality evaluation studies on the commercial vaccines. For the quality control of live attenuated JEV vaccine, we investigated the nucleotide sequence similarity of prME gene derived from five JEV vaccines commercially available in pigs in Korea. The Vero cells infected with JEV vaccines showed specific cytopathic effect, which was characterized by rounding and detached cells. In the phylogenetic analysis, all of the vaccine strains showed a close relationship with the original vaccine seed strain (Anyang 300) and clustered into the genotype 3. In comparison of the nucleotide and deduced amino acid sequences of prME genes with the original strain, all JEV vaccine strains showed high amino acid similarity ranging from 98.9% to 99.5%, but had several point mutations, probably due to high mutation rates of viral RNA polymerase by several virus passages. Even though the current JEV vaccine strains have been maintained and produced for a long period of time, the genetic characterization of them have been rarely changed. However, since the mid 1990's, molecular epidemiology of JEV has been changed sharply from genotype 3 to genotype 1 in Korea, further studies on new vaccine strains to genotype 1 is required for more effective prevention in the field.

• Proceedings of the Microbiological Society of Korea Conference
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• 2000.10a
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• pp.78-82
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• 2000

The AIDS epidemic continues unabated in many part of the world. After near two decades, no vaccine is available to combat the spread of this deadly disease. Much of the HIV -1 vaccine effort during the past decade has focused on the viral envelope glycoprotein, largely because it is the only protein that can elicit neutralizing antibodies (Nabs). Eliciting broadly cross-reactive Nabs has been a primary goal. The intrinsic genetic diversity of the viral envelope, however, has been one of the major impediments in vaccine development. We have recently completed a comprehensive study examining whether it is possible to elicit broadly acting Nabs by immunizing monkeys with mixtures of envelope proteins from multiple HIV -1 isolates. We compared the humoral immune responses elicited by vaccination with either single or multiple envelope proteins and evaluated the importance of humoral and non-humoral immune response in protection against a challenge virus with a homologous or heterologous envelope protein. Our results show that (1) Nab is the correlate of sterilizing immunity, (2) Nabs against primary HIV -1 isolates can be elicited by the live vector-prime/protein boost approach, and (3) polyvalent envelope vaccines elicit broader Nab response than monovalent vaccines. Nonetheless, our findings clearly indicate that the increased breadth of Nab response is by and large limited to strains included in the vaccine mixture and does not extend to heterologous non-vaccine strains. Our study strongly demonstrates how difficult it may be to elicit broadly reactive Nabs using envelope proteins and sadly predicts a similar fate for many of the vaccine candidates currently being evaluated in clinical trials. We have started to evaluate other vaccine candidates (e.g. genetically modified envelope proteins) that might elicit broadly reactive Nabs. We are also exploring other vaccine strategies to elicit potent cytotoxic T lymphocyte responses. Preliminary results from some of these experiments will be discussed.

• The Journal of Korean Society of Virology
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• v.26 no.2
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• pp.245-249
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• 1996

Hantaan virus vaccine was developed in 1988 and proved effective. This vaccine is a kind of inactivated vaccine, stable for two years when stored at $2-8^{\circ}C$. Almost virus vaccines including Hantaan virus vaccine are produced and kept in fluid state, and the immumogenicity can be easily destroyed at room temperature or at higher temperature. Therefore the vaccines should be kept in the refrigerator to maintain the immunogenicity. In this study, glucose and/or lactose was added as a stabilizer into Hantaan virus vaccine to increase the stability and dried in vaccum with ethanol treatment. 5% glucose and or lactose in Hantaan virus vaccine most effectively increased the stability of vaccine and maintained the immunogenicity at least for three months at room temperature. But drying with ethanol treatment did not help increasing the stability. These results suggest that glucose and lactose could be good stabilizer of virus vaccines.

• Applied Biological Chemistry
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• v.48 no.4
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• pp.301-310
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• 2005

Foot-and-mouth disease (FMD) is a highly contagious disease of mammals and has a great potential for causing severe economic loss in susceptible cloven-hoofed animals, such as cattle, pigs, sheep, goats and buffalo. FMDV, a member of the Aphthovirus genus in the Picornaviridae family, is a non-enveloped icosahedral virus that contains a positive sense RNA of about 8.2 kb in size. The genome carries one open reading frame consisting of 3 regions: capsid protein coding region P1, replication related protein coding region P2, and RNA-dependent RNA polymerase coding region P3. FMDV infects pharynx epithelial cell in the respiratory tract and viral replication is active in lung epithelial cell. Morbidity is extremely high. A FMD outbreak in Korea in 2002 caused severe economic loss. Although intense research is undergoing to develop appropriate drugs to treat FMDV infection, there is no specific therapeutic for controlling FMDV infection. Moreover, there is an increasing demand for the development of vaccine strategies against FMDV infection in many countries. In this report, more effective prevention strategies against FMDV infection were reviewed.

• IMMUNE NETWORK
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• v.23 no.4
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• pp.33.1-33.13
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• 2023

Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been acknowledged as an effective mean of preventing infection and hospitalization. However, the emergence of highly transmissible SARS-CoV-2 variants of concern (VOCs) has led to substantial increase in infections among children and adolescents. Vaccine-induced immunity and longevity have not been well defined in this population. Therefore, we aimed to analyze humoral and cellular immune responses against ancestral and SARS-CoV-2 variants after two shots of the BNT162b2 vaccine in healthy adolescents. Although vaccination induced a robust increase of spike-specific binding Abs and neutralizing Abs against the ancestral and SARS-CoV-2 variants, the neutralizing activity against the Omicron variant was significantly low. On the contrary, vaccine-induced memory CD4⁺ T cells exhibited substantial responses against both ancestral and Omicron spike proteins. Notably, CD4⁺ T cell responses against both ancestral and Omicron strains were preserved at 3 months after two shots of the BNT162b2 vaccine without waning. Polyfunctionality of vaccine-induced memory T cells was also preserved in response to Omicron spike protein. The present findings characterize the protective immunity of vaccination for adolescents in the era of continuous emergence of variants/subvariants.

• IMMUNE NETWORK
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• v.2 no.1
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• pp.1-5
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• 2002

Estimated number of adults and children newly infected with HIV-1 during 2001 alone is 5 million in total. An effective vaccine, in addition to education & public health approaches, has been believed to be the best option to stop the HIV-1 transmission, especially for developing countries. Among AIDS vaccine candidates, DNA vaccine is relatively safe and, in a certain extent, mimics some attributes of live attenuated vaccine, with regard to in vivo gene expression & the type of immunity induced. We recently demonstrated that DNA vaccines expressing SIVmac239 structural and regulatory genes, augmented with coadministration of IL-12 mutant induced the strongest T cell responses, resulting in low to undetectable setpoint viral loads, stable $CD4^+$ T cell counts, and no evidence of clinical diseases or mortality by day 420 after challenge. This finding is the second demonstration, following the protective result of live attenuated SIV vaccine in SIVmac-rhesus monkey model, which was known to have safety problem. So, our DNA vaccines could give a significant impact on HIV-1 epidemic by slowing or stopping the spread of HIV-1, leading to eventual eradication of HIV-1 and AIDS in the population.

• BMB Reports
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• v.31 no.5
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• pp.432-443
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• 1998

The poliovirus Sabin 1 strain has features that make it a particularly attractive live recombinant mucosal vaccine vehicle. Sabin 1 cDNA was manipulated to have multiple cloning sites and a viral specific 3C-protease cutting site at the N-terminal end of the polyprotein. The gene for the N-terminal 169 amino acids of the HIV-1 p24 was cloned into the multiple cloning site of the manipulated Sabin cDNA. A recombinant progeny virus was produced from HeLa cells when it was transfected with the RNA synthesized from the p24-Sabin chimeric cDNA. The recombinant progeny virus expresses substantial amounts of the HIV-1 p24 protein, which was clearly detected in the infected cell lysates and culture supernatants in Western blot experiments with rabbit anti-p24 serum and AIDS patients' sera. Differing from the Mahoney strain, the recombinant Sabin 1 poliovirus maintained the foreign gene stably during the subsequent passages. Replication capacity was about 1 to 1.5 log lower than that of the wild-type Sabin 1. Other physicochemical stability characteristics of the recombinant virus were similar to that of the wild-type Sabin 1. These results suggest that the manipulated Sabin 1 poliovirus can be used as a live viral vaccine vector for the development of mucosal vaccines.

• Journal of Microbiology and Biotechnology
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• v.21 no.2
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• pp.170-175
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• 2011

This study was carried out for the molecular level identification of recombinant protein vaccine efficacy, by oral feeding against white spot syndrome virus infection, with the comparison of viral mRNA transcriptional levels in shrimp cells. For the determination of WSSV dilution ratio for the vaccination experiment by oral feeding, in vivo virus titration was carried out using different virus dilutions of virus stock ($1{\times}10^2$, $2{\times}10^2$, and $1{\times}10^3$). Among the dilution ratios, $2{\times}10^2$ diluted WSSV stock was chosen as the optimal condition because this dilution showed 90% mortality at 10 days after virus injection. Recombinant viral proteins, rVP19 and rVP28, produced as protein vaccines were delivered in shrimps by oral feeding. The cumulative mortalities of the shrimps vaccinated with rVP19 and rVP28 at 21 days after the challenge with WSSV were 66.7% and 41.7%, respectively. This indicates that rVP28 showed a better protective effect against WSSV in shrimp than rVP19. Through the comparison of mRNA transcriptional levels of viral genes from collected shrimp organ samples, it was confirmed that viral gene transcriptions of vaccinated shrimps were delayed for 4~10 days compared with those of unvaccinated shrimps. Protection from WSSV infection in shrimp by the vaccination with recombinant viral proteins could be accomplished by the prevention of entry of WSSV due to the shrimp immune system activated by recombinant protein vaccines.

• Biomolecules & Therapeutics
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• v.26 no.3
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• pp.242-254
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• 2018

Defensins are antimicrobial peptides that participate in the innate immunity of hosts. Humans constitutively and/or inducibly express ${\alpha}$- and ${\beta}$-defensins, which are known for their antiviral and antibacterial activities. This review describes the application of human defensins. We discuss the extant experimental results, limited though they are, to consider the potential applicability of human defensins as antiviral agents. Given their antiviral effects, we propose that basic research be conducted on human defensins that focuses on RNA viruses, such as human immunodeficiency virus (HIV), influenza A virus (IAV), respiratory syncytial virus (RSV), and dengue virus (DENV), which are considered serious human pathogens but have posed huge challenges for vaccine development for different reasons. Concerning the prophylactic and therapeutic applications of defensins, we then discuss the applicability of human defensins as antivirals that has been demonstrated in reports using animal models. Finally, we discuss the potential adjuvant-like activity of human defensins and propose an exploration of the 'defensin vaccine' concept to prime the body with a controlled supply of human defensins. In sum, we suggest a conceptual framework to achieve the practical application of human defensins to combat viral infections.

• The Journal of Korean Society of Virology
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• v.30 no.2
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• pp.113-124
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• 2000

We had isolated 8 viruses from 91 specimen collected at southwest Cheju Province during early spring 1998 and 2 viruses from 9 specimen collected at Chung Nam Province during early spring 1999. To perform cross-reactivity among 4 mumps vaccine strains and 10 wild-type mumps viruse isolates, we immunized mice and took antisera against each virus. There were no antibody titer differences by indirect immunofluorescence assay (IFA), but most isolated mumps viruses showed a little cross-reactivities with Jeryl Lynn and Rubini strains. It has shown similar result by haemagglutination-inhibition (HAI) test. These results show that 4 mumps strains used as vaccine have the protection ability against endemic wild-type mumps viruses. Also the SH gene analysis was performed to identify genotypes. Most isolated mumps viruses belonged to genotype D. These results indicate that endemic mumps viruses in Korea are different to ones isolated in Japan and China.