Requirements for improved vaccines against foot-and-mouth disease epidemics

The Korean Vaccine Society 2013 Clinical and Experimental Vaccine Research Vol.2 No.1

<P>Inactivated foot-and-mouth disease (FMD) vaccines are currently used worldwide. With the emergence of various FMD virus serotypes and subtypes, vaccines must become more suitable for field-based uses under the current circumstances in terms of the fast and proper selection of vaccine strains, an extended vaccine development period for new viruses, protecting against the risk of virus leakage during vaccine manufacture, counteracting the delayed onset of immune response, counteracting shorter durations of immunity, and the accurate serological differentiation of infected and vaccinated animals and multiple vaccination. The quality of vaccines should then be improved to effectively control FMD outbreaks and minimize the problems that can arise among livestock after vaccinations. Vaccine improvement should be based on using attenuated virus strains with high levels of safety. Moreover, when vaccines are urgently required for newly spread field strains, the seed viruses for new vaccines should be developed for only a short period. Improved vaccines should offer superior immunization to all susceptible animals including cattle and swine. In addition, they should have highly protective effects without persistent infection. In this way, if vaccines are developed using new methods such as reverse genetics or vector vaccine technology, in which live viruses can be easily made by replacing specific protective antigens, even a single vaccination is likely to generate highly protective effects with an extended duration of immunity, and the safety and stability of the vaccines will be assured. We therefore reviewed the current FMD vaccines and their adjuvants, and evaluated if they provide superior immunization to all susceptible animals including cattle and swine.</P>

The present and future of rabies vaccine in animals

Yang, Dong-Kun,Kim, Ha-Hyun,Lee, Kyung-Woo,Song, Jae-Young The Korean Vaccine Society 2013 Clinical and Experimental Vaccine Research Vol.2 No.1

<P>An effective strategy for preventing rabies consists of controlling rabies in the host reservoir with vaccination. Rabies vaccine has proven to be the most effective weapon for coping with this fatal viral zoonotic disease of warm-blooded animals, including human. Natural rabies infection of an individual is always associated with exposure to rabid animals, and the duration of clinical signs can vary from days to months. The incubation period for the disease depends on the site of the bite, severity of injury, and the amount of infecting virus at the time of exposure. The mortality of untreated cases in humans is 100%. Over the last 100 years, various rabies vaccines have been developed and used to prevent or control rabies in animals, such as modified live vaccine, inactivated rabies vaccine, and oral modified live vaccine. These have proved safe and efficacious worldwide. New-generation rabies vaccines, including recombinant rabies virus-based vaccines, vectored vaccines, DNA-based vaccines, and plant vaccines, have been explored to overcome the limitations of conventional rabies vaccines. This article discusses current and next-generation rabies vaccines in animals.</P>

H9N2 avian influenza virus in Korea: evolution and vaccination

Lee, Dong-Hun,Song, Chang-Seon The Korean Vaccine Society 2013 Clinical and Experimental Vaccine Research Vol.2 No.1

<P>Low pathogenic avian influenza (LPAI) H9N2 viruses have been circulating in the Eurasian poultry industry resulting in great economic losses due to declined egg production and moderate to high mortality. In Korea, H9N2 LPAI was first documented in 1996 and it caused serious economic loss in the Korean poultry industry, including layer and broiler breeder farms. Since then, the H9N2 viruses that belong to the Korea group have been prevalent in chickens and have continuously evolved through reassortment in live bird markets. To control LPAI outbreaks, since 2007, the Korean veterinary authority has permitted the use of the inactivated oil adjuvant H9N2 LPAI vaccine. Although only oil-based inactivated vaccine using the egg-passaged vaccine virus strain (A/chicken/Korea/01310/2001) is permitted and used, several new technology vaccines have been recently suggested for the development of cost-effective and highly immunogenic vaccines. In addition, several different differentiation of infected from vaccinated animals (DIVA) strategies have been suggested using appropriate vaccines and companion serologic tests for discriminating between naturally infected and vaccinated animals. Recent reports demonstrated that the Korean LPAI H9N2 virus underwent antigenic drift and evolved into distinct antigenic groups and thus could escape from vaccine protection. Therefore, improved vaccination strategies including periodic updates of vaccine seed strains are required to achieve efficient control and eradication of LPAI H9N2 in Korea. Further, vaccination should be part of an overall integrated strategy to control the disease, including continued nation-wide surveillance, farm biosecurity, and DIVA strategy.</P>

New vaccines against influenza virus

Lee, Young-Tae,Kim, Ki-Hye,Ko, Eun-Ju,Lee, Yu-Na,Kim, Min-Chul,Kwon, Young-Man,Tang, Yinghua,Cho, Min-Kyoung,Lee, Youn-Jeong,Kang, Sang-Moo The Korean Vaccine Society 2014 Clinical and Experimental Vaccine Research Vol.3 No.1

<P>Vaccination is one of the most effective and cost-benefit interventions that prevent the mortality and reduce morbidity from infectious pathogens. However, the licensed influenza vaccine induces strain-specific immunity and must be updated annually based on predicted strains that will circulate in the upcoming season. Influenza virus still causes significant health problems worldwide due to the low vaccine efficacy from unexpected outbreaks of next epidemic strains or the emergence of pandemic viruses. Current influenza vaccines are based on immunity to the hemagglutinin antigen that is highly variable among different influenza viruses circulating in humans and animals. Several scientific advances have been endeavored to develop universal vaccines that will induce broad protection. Universal vaccines have been focused on regions of viral proteins that are highly conserved across different virus subtypes. The strategies of universal vaccines include the matrix 2 protein, the hemagglutinin HA2 stalk domain, and T cell-based multivalent antigens. Supplemented and/or adjuvanted vaccination in combination with universal target antigenic vaccines would have much promise. This review summarizes encouraging scientific advances in the field with a focus on novel vaccine designs.</P>

Efficacy of a commercial live attenuated <i>Lawsonia intracellularis</i> vaccine in a large scale field trial in Korea

Park, Sangshin,Lee, Joong-Bok,Kim, Kyung-Jin,Oh, Yu-Sik,Kim, Man-Ok,Oh, Yu-Ri,Hwang, Min-A,Lee, Jung-Ah,Lee, Sang-Won The Korean Vaccine Society 2013 Clinical and Experimental Vaccine Research Vol.2 No.2

<P><B>Purpose</B></P><P>Porcine proliferative enteropathy (PPE) is known as one of the most important risk factors causing economic losses in swine industry worldwide. This study was conducted to evaluate the efficacy of a commercial oral attenuated <I>Lawsonia intracellularis</I> vaccine (Enterisol Ileitis) against PPE under a commercial pig farm condition in Korea.</P><P><B>Materials and Methods</B></P><P>Thirty two-day-old 672 piglets were randomly allocated into vaccinated and control groups. All piglets in the vaccinated group were inoculated with a commercial attenuated <I>L. intracellularis</I> vaccine as following the manufacturer's instruction. Body weights of all pigs in both groups were measured on the vaccination day and 6, 14, and 20 weeks post vaccination and an average daily weight gain (ADWG) was calculated. Health status was observed biweekly during the whole trial.</P><P><B>Results</B></P><P>The vaccinated group showed significantly higher body weight (p<0.05) and ADWG (p<0.05) than those of the control group. The vaccinated group had significantly reduced impairments in activity, growth, defecation frequency, and stool hardness (p<0.05). Additional health benefits and improved weight gain by the vaccination produced a 4.2:1 return of investment, and the higher gross margin was $4.80 per pig.</P><P><B>Conclusion</B></P><P>Our finding suggests that the <I>L. intracellularis</I> vaccine program has effects on the substantial health and economic benefits in the Korean swine industry.</P>

Suggested guidelines for vaccination of pigs in Korea

Lee, Won Hyung,Yoo, Han Sang The Korean Vaccine Society 2015 Clinical and Experimental Vaccine Research Vol.4 No.1

<P>There is no published guideline for the vaccination to pigs even though several vaccine companies suggested the program based on their products. It is very difficult to standardize the program because most of the veterinary vaccines are containing several multivalent antigens depending on the companies. Now, we are suggesting the vaccine programs based on the current situation.</P>

Development of porcine respiratory and reproductive syndrome virus replicon vector for foot-and-mouth disease vaccine

Jeeva, Subbiah,Lee, Jung-Ah,Park, Seung-Yong,Song, Chang-Seon,Choi, In-Soo,Lee, Joong-Bok The Korean Vaccine Society 2014 Clinical and Experimental Vaccine Research Vol.3 No.1

<P><B>Purpose</B></P><P>Foot-and-mouth disease (FMD) is an economically important global animal disease. To control FMD virus (FMDV) outbreaks, a lot of different novel approaches have been attempted. In this study, we proposed a novel porcine reproductive and respiratory syndrome virus (PRRSV) as a replicon vector to express FMDV structural protein.</P><P><B>Materials and Methods</B></P><P>PRRSV infectious clone (PRRSVK418DM) was used to develop an expression vector through the reverse genetic manipulation of PRRSV; FMDVP12A3C gene of serotype O was synthesized and used for an antigen. MARC-145 cells (African green monkey kidney epithelial cell line) were used for electroporation mediated transfection. The transfection or the expression of P12A3C and N protein of PRRSV was analyzed by either replicon containing PRRSV alone or by co-infection of helper PRRSV.</P><P><B>Results</B></P><P>We constructed PRRSVK418DM replicon vector containing FMDVP12A3C, and genome sequences were confirmed by subsequent sequence analysis. <I>In vitro</I> expression of P12A3C and PRRSV N protein was confirmed by immunofluorescence antibody assay using antibodies specific for PRRSV N protein (anti-PRRSV N MAb), FMDV-VP1 (anti-VP1 MAb).</P><P><B>Conclusion</B></P><P>The results indicate that PRRSV replicon vector can be a promising novel vector system to control FMDV and useful for vaccine development in the future.</P>

Evaluation of EZplex MTBC/NTM Real-Time PCR kit: diagnostic accuracy and efficacy in vaccination

Lee, Suengmok,Hwang, Kyung-A,Ahn, Ji-Hoon,Nam, Jae-Hwan The Korean Vaccine Society 2018 Clinical and Experimental Vaccine Research Vol.7 No.2

<P><B>Purpose</B></P><P>Tuberculosis (TB) is mainly caused by <I>Mycobacterium tuberculosis</I>, which is a pathogenic mycobacterial species grouped under <I>Mycobacterium tuberculosis</I> complex (MTBC) with four other pathogenic mycobacterial species. The mycobacteria not included in MTBC are known as nontuberculous mycobacteria (NTM), and cause several pulmonary diseases including pneumonia. Currently, NTM occurrences in TB-suspected respiratory specimens have increased, due to which, precise detection of MTBC and NTM is considered critical for the diagnosis and vaccination of TB. Among the various methods available, real-time PCR is frequently adopted for MTBC/NTM detection due to its rapidness, accuracy, and ease of handling. In this study, we evaluated a new real-time PCR kit for analytical and clinical performance on sputum, bronchial washing, and culture specimens.</P><P><B>Materials and Methods</B></P><P>For assessing its analytical performance, limit of detection (LOD), reactivity, and repeatability test were performed using DNA samples. To evaluate clinical performance, 612 samples were collected and clinically tested at a tertiary hospital.</P><P><B>Results</B></P><P>LOD was confirmed as 0.584 copies/µL for MTBC and 47.836 copies/µL for NTM by probit analysis (95% positive). For the reactivity test, all intended strains were detected and, in the repeatability test, stable and steady results were confirmed with coefficient of variation ranging from 0.36 to 1.59. For the clinical test, sensitivity and specificity were 98.6%–100% and 98.8%–100% for MTBC and NTM, respectively.</P><P><B>Conclusion</B></P><P>The results proved the usefulness of the kit in TB diagnosis. Furthermore, it could be adopted for the assessment of vaccine efficacy.</P>

Oral immunization of mice with recombinant rabies vaccine strain (ERAG3G) induces complete protection

Yang, Dong-Kun,Kim, Ha-Hyun,Choi, Sung-Suk,Kim, Jong-Taek,Jeong, Woong-Ho,Song, Jae-Young The Korean Vaccine Society 2015 Clinical and Experimental Vaccine Research Vol.4 No.1

<P><B>Purpose</B></P><P>New rabies vaccine bait for both pets and raccoon dogs residing in Korea is needed to eradicate rabies infection among animals. In this study, we constructed a recombinant rabies virus (RABV), the ERAG3G strain, using a reverse genetics system. Then we investigated the efficacy of this strain in mice after oral administration and the safety of this strain in cats after intramuscular administration.</P><P><B>Materials and Methods</B></P><P>The ERAG3G strain was rescued in BHK/T7-9 cells using the full-length genome mutated at the amino acid position 333 of the glycoprotein gene of RABV and helper plasmids. Four-week-old mice underwent one or two oral administrations of the ERAG3G strain and were challenged with the highly virulent RABV strain CVSN2c 14 days after the second administration. Clinical symptoms were observed and body weights were measured every day after the challenge.</P><P><B>Results</B></P><P>All mice showed complete protection against virulent RABV. In addition, cats intramuscularly inoculated with the ERAG3G strain showed high antibody titers ranging from 2.62 to 23.9 IU/mL at 28-day postinoculation.</P><P><B>Conclusion</B></P><P>The oral immunization of the ERAG3G strain plays an important role in conferring complete protection in mice, and intramuscular inoculation of the ERAG3G strain induces the formation of anti-rabies neutralizing antibody in cats.</P>

Mucosal vaccine adjuvants update

Rhee, Joon Haeng,Lee, Shee Eun,Kim, Soo Young The Korean Vaccine Society 2012 Clinical and Experimental Vaccine Research Vol.1 No.1

<P>Mucosal vaccination, capable of inducing protective immune responses both in the mucosal and systemic immune compartments, has many advantages and is regarded as a blue ocean in the vaccine industry. Mucosal vaccines can offer lower costs, better accessability, needle-free delivery, and higher capacity of mass immunizations during pandemics. However, only very limited number of mucosal vaccines was approved for human use in the market yet. Generally, induction of immune responses following mucosal immunization requires the co-administration of appropriate adjuvants that can initiate and support the effective collaboration between innate and adaptive immunity. Classically, adjuvant researches were rather empirical than keenly scientific. However, during last several years, fundamental scientific achievements in innate immunity have been translated into the development of new mucosal adjuvants. This review focuses on recent developments in the concepts of adjuvants and innate immunity, mucosal immunity with special interest of vaccine development, and basic and applied researches in mucosal adjuvant.</P>