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To control foot-and-mouth disease (FMD) outbreaks that originated in Jincheon County in South Korea between 2014 and 2015, several commercial vaccines were studied for their efficacy and serological performance in the field. In this study, the efficacy of the O SKR 7/10 vaccine was evaluated by challenge with the FMD virus (FMDV) O/Jincheon/SKR/2014 (O Jincheon), which has the same O/SEA/Mya-98 lineage as the O/SKR/7/10 strain that was isolated in 2010 in South Korea, in FMD-seronegative pigs. Full protection against the O Jincheon virus was demonstrated as early as 14 days postvaccination, which was explained by the strong serological relationship (r1 value: ≥ 0.92) between the O Jincheon and O SKR 2010 viruses. However, in the field trial, no satisfactory serological elevations against FMDV were observed, even in the double-vaccinated groups. Therefore, it can be concluded that the O SKR 7/10 vaccine may need to be improved to overcome the interference effects from the high levels of maternally-derived antibodies generated due to the mandatory nationwide vaccination of sows in South Korea.

After massive foot-and-mouth disease (FMD) outbreaks originated from Jincheon County from Dec. 2014 to Apr. 2015, the effectiveness of the previous FMD vaccine containing only the O1 Manisa as the O antigen, O1 Manisa + A Malaysia 97 + Asia 1 Sharmir trivalent vaccine, was questioned in South Korea, and a change in the O antigen in FMD vaccines was demanded to control the FMD caused by FMDV O/Jincheon/SKR/2014, the O Jincheon strain. Therefore, the efficacies of O1 Manisa + O 3039 bivalent vaccine and O 3039 monovalent vaccine were studied for cross-protection against heterologous challenge with the O Jincheon strain. In this study, the efficacy of the O1 Manisa + O 3039 bivalent vaccine was better than that of the O 3039 monovalent vaccine, even though the serological relationship (r1 value) between O Jincheon and O 3039 was matched according to the OIE Terrestrial Manual. According to serological test results from vaccinated specific pathogen free pigs, virus neutralization test titers against Jincheon were good estimates for predicting protection against challenge. A field trial of the O1 Manisa + O 3039 bivalent vaccine was performed to estimate the possibility of field application in conventional pig farms, especially due to concerns about the effect of maternally derived antibodies (MDA) in field application of the FMD vaccine. According to the result of the field trial, the O1 Manisa + O 3039 bivalent vaccine was considered to overcome MDA. The results of the efficacy and field trials indicated that the O1 Manisa + O3039 vaccine could be suitable to replace previous FMD vaccines to control the FMD field situation caused by O Jincheon FMDV.

Classical swine fever (CSF) is a highly contagious systemic hemorrhagic viral disease of pigs. Wild boar plays a crucial role in the epidemiology of CSF. Between 2010 and 2014, samples were collected nationwide from 6,654 wild boars hunted in South Korea. Anti-CSF antibodies were identified in 0.59% (39 of 6,654) of the wild boar samples using a virus neutralization test and were primarily detected in wild boars living close to the demilitarized zone and the area of the Taebaek Mountains surroundings. The CSF virus (subgroup 2.1b) was isolated from two wild boars captured in a nearby border area. The criteria used to define high-risk areas for targeted CSF surveillance in South Korea should be further expanded to include other regions nationwide.

As veterinary medicine industry has grown up steadily, the government quality control of veterinary medicine in market has been performed since 1964. The result of post-market surveillance assay from 2009 to 2012 was analyzed in this study. The average violation rate of all veterinary medicines, was 3.2%, 2.8%, 2.8% and 1.4% in 2009, 2010, 2011 and 2012, respectively. The total average violation rate in the category of antibiotics, other drugs except antibiotics, biologics were 1.2%, 4.4% and 0.8%, respectively. The violations due to insufficiency of major active ingredient content occupied 76.7% among the total violations. The most frequent violated in antibiotics were ampicillin and tylosin, followed by sulfonamides, penicillins etc. In case of other drugs except antibiotics, vitamin A and glucocorticoids (dexamethasone and prednisolone) were violated frequently. The overall trend of violation rates gradually decreased from 2009 to 2012, suggesting that quality of veterinary medicines has improved according to Korea Veterinary Good Manufacturing Practice (KVGMP) system settled down in 1988.

Since the 1980's, several kinds of inactivated bovine viral diarrhea virus (BVDV) vaccines have been used to immunize domestic animals such as cattle and goat in Korea. Immunogenicity of the BVDV vaccines has been checked by the Korean Veterinary Authority using laboratory animals. In this study, we applied a molecular method to investigate the genetic characterization of the BVDV genes in six commercial inactivated BVDV vaccines, and determined the efficiency of two extraction reagents (i.e., sodium citrate or isopropyl myristate) to separate the vaccine antigens from the antigen/adjuvant complexes. Six partial non-coding regions (288 bp) were successfully amplified with specific primer sets, which demonstrated that sodium citrate is more efficient in extracting viral RNA from inactivated gel vaccines than isopropyl myristae. In addition, we identified the virus strains from the vaccines by analyzing the nucleotide sequences of the 5' non-coding region (NCR) of BVDV. The nucleotide sim-ilarity of the partial 5' NCR ranged from 95.1 to 100% among BVDV vaccine strains, respectively, in-dicating that a few manufacturers used different BVDV strains to produce their vaccines.

A high rate of genetic and antigenic variability among porcine reproductive and respiratory syndrome viruses (PRRSVs) hampers effective prevention and control of the disease caused by PRRSV. The major envelope protein (GP5) encoded by the ORF5 of PRRSV has a critical role in inducing virus neutralizing (VN) antibody and cross protection among different strains of PRRSV. This study was conducted to identify sequence elements related to cross neutralization by comparing the ORF5 sequences of 69 field isolates in conjunction with their susceptibility to VN antibody raised against the VR2332 strain in vitro and in vivo . Five common variable sites (amino acid position 32–34, 38–39, 57–59, 137 and 151) were identified between susceptible and resistant viral isolates. Mutants whose ORF5 amino acid sequences were substituted with the sequences corresponding to the 5 identified common variable sites individually or concurrently were generated from a VR2332-backboned infectious clone by site mutagenesis. The change in the susceptibility of the mutants to VN antibodies specific for VR2332 or a heterologous PRRSV was assessed to determine the association of those 5 identified sites with cross neutralization. Among the five sites, the changes of amino acid sequences at three sites (32–34, 38–39, and 57–59) located in the N-terminal ectodomain of ORF5 significantly influenced the susceptibility of the mutant viruses to VN antibody, suggesting that sequence homology at these sites can be utilized as genetic markers to predict the degree of cross neutralization among different PRRSVs.

The classical swine fever (CSF) vaccine, which is derived from the LOM strain of the CSF virus (CSFV), induces protective immunity against CSFV infection. However, several factors influence vaccine efficacy. Evidence suggests that infection by porcine reproductive and respiratory syndrome virus (PRRSV) and/or porcine circovirus 2 (PCV2) reduces the efficacy of several vaccines. Here, we examined the effect of PRRSV or PCV2 alone or co-infection by PRRSV/PCV2 on the potency of the LOM vaccine in pigs. Neither CSFV antibody levels nor the period during which CSFV antigens were detectable in LOM-vaccinated pigs were negatively affected by infection by PRRSV or PCV2. However, co-infection with PRRSV/PCV2 may affect the replication or activity of the CSF vaccine virus in pigs vaccinated with the LOM strain, although CSFV antibody levels were not negatively affected. Nevertheless, the LOM vaccine afforded complete protection against a virulent strain of CSFV.

The present study aimed to evaluate the safety of the classical swine fever virus (CSFV) vaccine strain LOM in pregnant sows. Pregnant sows with free CSFV antibody were inoculated with a commercial LOM vaccine during early pregnancy (day 38; n=3) or mid-pregnancy (days 49-59; n=11). In pregnant sows vaccinated during the early stages of gestation, abortion (day 109) was observed in one case, with two stillbirths and seven mummified fetuses. The viability of live-born piglets was 34.9% in sows vaccinated during mid-pregnancy compared with 81.8% in the control group. Post-mortem examination of the organs of the sows and piglets did not reveal any pathological lesions caused by CSFV; however, CSFV RNA was detected in the organs of several vaccinated sows and their litters. The LOM strain was transmitted from sows with free CSFV antibody to their fetus, but did not appear to induce immune tolerance in the offspring from vaccinated pregnant sows. Side effects were not observed in pregnant sows with antibody to the LOM strain: transmission from sow to their litters and stillbirth or mummified fetuses. The LOM strain may induce sterile immunity and provide rapid, long-lasting, and complete protection against CSFV; however, it should be contraindicated in pregnant sows due to potential adverse effects in pregnant sows with free CSFV antibody.

Background: Viral agents associated with reproductive failure such as Aujeszky's disease virus (ADV), encephalomyocarditis virus (EMCV), and porcine parvovirus (PPV) have also been identified in European wild boar. To screen for the presence of antibodies against ADV, EMCV, and PPV from wild boar (Sus scrofa) in South Korea, 481 serum samples were collected from wild boar hunted between December 2010 and May 2011. Results: Of the 481 serum samples tested, 47 (9.8%) and 37 (7.7%) were seropositive for ADV and EMCV antibodies, respectively, based on a neutralization test (VNT), and 142 (29.5%) were seropositive for PPV antibodies based on a hemagglutination inhibition (HI) test. Conclusions: This was the first survey to identify the seroprevalence of the three major viruses associated with reproductive failure in the wild boar population of South Korea. Wild boar may act as a reservoir for many viruses that cause infectious diseases in domestic pigs. Thus, strict prevention and control measures, such as continuous wildlife disease surveillance and strategic methods of downsizing the population density, should be implemented to prevent disease transmission from wild boar to domestic pigs.

In this study, we successfully developed a ssDNA aptamer pairs by using an advanced immobilization-free SELEX method with affinity-based selection and counter-screening process at every round. By implementing this method, two different aptamers specifically binding to bovine viral diarrhea virus type 1(BVDV type 1) with high affinity were successfully screened. This aptamer pair was applied to ultrasensitive detection platform for BVDV type 1 in a sandwich manner. The ultrasensitive detection of BVDV type 1 using one of aptamers conjugated with gold nanoparticles was obtained in aptamer–aptamer sandwich type sensing format, with the limit of detection of 800 copies/ml, which is comparable to a real-time PCR method.

Classical swine fever is a disease that is devastating the pig industry worldwide. Here, we report the complete genome sequences of two classical swine virus strains (YC11WB and PC11WB), isolated from Korean wild boars in 2011. Both strains belong to subgenotype 2.1b. The complete genome sequences of PC11WB and YC11WB are more similar to that of strain ZJ0801 (isolated in China) than to that of the SW03 strain isolated from domestic pigs in South Korea.

Classical swine fever (CSF), a highly contagious disease that affects domestic pigs and wild boar, has serious economic implications. The present study examined the virulence and transmission of CSF virus strain YC11WB (isolated from a wild boar in 2011) in breeding wild boar. Virulence of strain YC11WB in domestic pigs was also examined. Based on the severe clinical signs and high mortality observed among breeding wild boar, the pathogenicity of strain YC11WB resembled that of typical acute CSF. Surprisingly, in contrast to strain SW03 (isolated from breeding pigs in 2003), strain YC11WB showed both acute and strong virulence in breeding pigs. None of three specific monoclonal antibodies (7F2, 7F83, and 6F65) raised against the B/C domain of the SW03 E2 protein bound to the B/C domain of strain YC11WB due to amino acid mutations (720K→R and 723N→S) in the YC11WB E2 protein. Although strains YC11WB and SW03 belong to subgroup 2.1b, they had different mortality rates in breeding pigs. Thus, if breeding pigs have not developed protective immunity against CSF virus, they may be susceptible to strain YC11WB transmitted by wild boar, resulting in severe economic losses for the pig industry.

No information is currently available on porcine reproductive and respiratory syndrome virus (PRRSV) infection in wild boars (Sus scrofa) in Korea. In this study, the status of PRRS in wild boars was investigated. Blood samples were collected from 267 wild boars from eight provinces in Korea. Four of the samples tested (1.5%) were positive for PRRSV antibodies and eight (3.0%) were positive for antigens. Of the virus-positive samples, three and five samples were typed as containing European (EU, type 1) or North American (NA, type 2) viruses, respectively. Two amplicons (one from type 1 and one from type 2) were used to analyze the PRRSV open reading frame 7 (ORF7) sequence. The nucleotide sequences of type 1 PRRSV ORF7 had identities between 96.1% and 98.4% with PRRSVs from domestic pigs in Korea. The sequences of type 2 PRRSV ORF7 had identities of 100% with the PRRSV strain VR-2332, which was prototypic North American strain. These results show that PRRSVs are present in wild boars in Korea, and effective PRRSV surveillance of the wild boar population might therefore be useful for disease control.

Two attenuated vaccines, Ingelvac PRRS MLV and Ingelvac PRRS ATP, derived from VR2332 and JA142, respectively, have been used to control porcine reproductive and respiratory syndrome (PRRS) virus. However, there have been several field reports concerning the reversion of the vaccine virus to virulence. Furthermore, viruses genetically indistinguishable from the vaccines and wild-type parental viruses have been detected in clinical PRRS cases, raising the need for a better differential tool. As the vaccine viruses replicated better and produced bigger plaques in MARC-145 cells than did the wild-type parental strains, the following study was conducted to determine if the growth difference in MARC-145 cells can be utilized to differentiate a vaccine-like virus (VLV) from a wild-type virus and to identify genetic markers corresponding to such phenotype of the vaccine viruses. The relatedness of 83 field isolates collected between 1996 and 2005 to VR2332 and JA142 was classified genetically and antigenically. Thirteen of 25 VR2332-related viruses and 9 of 10 JA142-related viruses were determined as VLVs, since those viruses produced plaques similar to those by the vaccine viruses. Four unique amino acids each were identified throughout structural genes for MLV and ATP. Among those, F 10 in open reading frame 2 (ORF2) of MLV and E 85 and Y 165 in ORF3 of ATP were stable during pig passages. When the sequences unique for MLV were incorporated into an infectious clone constructed based on VR2332, the virus growth and resultant plaque size in MARC-145 cells were increased, suggesting that these sequences can be used as genetic markers for VLVs.

One hundred ninety-five rabies cases in cattle were identified in South Korea since 1993. As most of rabies cases have a relation to rabid Korean raccoon dogs (Nyctereutes procyonoides koreensis), vaccination to animals including cattle is mandatory in rabies risk region. In order to minimize fatal rabies in animals, eradication policy of the disease has been achieved by controlling reservoirs and by mass vaccination. In this study, we compared the antibody response in cattle and guinea pigs inoculated with rabies vaccines commercially available in Korea. Each group of cattle in Gangwon-do was vaccinated intramuscularly with either one of five commercial inactivated vaccines or a live attenuated rabies vaccine (designated as A to F). Serum samples at the time of vaccination and four weeks post vaccination were obtained from the cattle and guinea pigs and were analyzed with virus neutralizing assay (VNA). Each group of cattle inoculating rabies vaccines showed significant virus neutralizing antibody titers (p < 0.05) ranging from 1.55 to 17.8 mean IU/ml compared with the non-vaccinated cattle and guinea pigs inoculated with 1/20 dose of vaccine showed relatively low VN antibody titers ranging from 0.23 to 6.1 mean IU/ml. All cattle immunized with A, C and F showed high VN antibody titers over 0.5 IU/ml and 62.5% and 37.5% of cattle inoculated with D and E showed protective antibody titer, respectively. This finding suggests that the inactivated or live attenuated rabies vaccination commercially available in Korea could induce protective antibody response in Korean cattle, but sero-conversion rate and sero-positive rate showing VN antibody titer over 0.5 IU/ml depend on vaccines.