Evaluation of Commercial Immunochromatographic Test Kits for the Detection of Canine Distemper Virus

The rapid diagnosis of canine distemper virus (CDV) helps to determine the treatment of dogs in veterinary clinics. We evaluated the performance of seven commercial rapid immunochromatographic test (RICT) kits for the detection of CDV. Six core dog viral pathogens (canine adenovirus type 1 and 2, canine coronavirus, canine parainfluenza virus, canine parvovirus, and rabies virus), five CDV strains (CD1901, Lederle, Rockborn, Onderstepoort, and Synder Hill), and three bacteria (Bordetella bronchiseptica, Leptospira canicola, and Staphylococus aureus) were used to determine the cross-reactivity and detection limits of the kits. The seven commercial RICT kits did not yield positive results with the six dog viruses or the three bacteria. All the RICT kits for CDV detected the Korean CDV isolate. The detection limits of the RICT kits for the Korean CDV isolate, CD1901, belonging to Asia 1 genotype ranged from 103.0 to 104.0 TCID50/mL. There was an average difference of 1.1 in scores judged by eye between four CDV vaccine strains and CD1901 strain. Therefore, the RICT kits enable the detection of CDV vaccine strains, but need to be improved to detect CDV circulating in dog populations in Korea.

Control of type O foot-and-mouth disease by vaccination in Korea, 2014–2015

On December 3, 2014, a type O foot-and-mouth disease (FMD) outbreak began in Korea. Although vaccinations were administered, FMD cases increased steadily for five months, and reached 185 cases by April 2015. Most of the affected animals were pigs, which are vulnerable to vaccination. The FMD virus belonged to the South-East Asia (SEA) topotype that had been observed three times in Korea between April 2010 and July 2014. However, the FMD virus isolated in December 2014 had a unique feature; that is, partial deletion of the 5′ non-coding region, a deletion not seen in previous SEA topotype isolates identified in Korea. We conclude that this outbreak included the introduction of a new FMD strain to Korea, and that Korea was now affected by genetically similar FMD virus strains that are related to those from neighboring countries.

Novel foot-and-mouth disease virus in Korea, July-August 2014

Despite nation-wide immunization with O, A, and Asia 1 type vaccines in Republic of Korea, foot-and-mouth disease type O occurred again in July 2014 after three years and three months. This virus was a Mya-98 strain of the Southeast Asian topotype and was most similar to the identified type that circulated in East Asia in 2014. This was new virus with the deletion of 23 amino acids in 3A/3B1 region and low pathogenic property.

Antigenic properties and virulence of foot-and-mouth disease virus rescued from full-length cDNA clone of serotype O, typical vaccine strain

We cloned the full-length cDNA of O Manisa, the virus for vaccinating against foot-and-mouth disease. The antigenic properties of the virus recovered from the cDNA were similar to those of the parental virus. Pathogenesis did not appear in the pigs, dairy goats or suckling mice, but neutralizing antibodies were raised 5-6 days after the virus challenge. The utilization of O Manisa as a safe vaccine strain will increase if recombinant viruses can be manipulated by inserting or removing a marker gene for differential serology or replacing the protective gene from another serotype.

Human Adenovirus Type 5 as a Delivery Vector is Not Neutralized in Field Serum Samples of Cattle, Pig, and Goat of Republic of Korea

Human adenovirus type 5 (hAd5) vectors have been demonstrated to be useful vehicles for gene expressions in animals. However, it has not been reported whether hAd5 transduction might be hampered in the sera of livestock animals in Republic of Korea. We collected 205 samples of livestock animals, such as pig (n=84), cattle (n=84), and goat (n=37) in Korea. The neutralizing antibody (NAb) titers to hAd5 virus were less than 15 in most of samples. Only 8% of goat samples had a NAb titer of 15 or 30. Thus, we showed that hAd5 virus was not neutralized in sera from cattle, pig, and goat, and suggest that the hAd5 vector could be used for the effective delivery of vaccines or proteins in livestock animals in the field.

Adenovirus Expressing Human Interferon Inhibits Replication of Foot and Mouth Disease Virus and Reduces Fatal Rate in Mice

Interferon is an important cytokine that plays a critical role in the initial host defense against viral infection. Recombinant human adenoviruses expressing human interferon-alpha (Ad-HIFNalpha) or pig interferon-beta fused with interleukin-18 (Ad-PIFNbeta-IL18) were constructed and used to induce an early protective response against foot and mouth disease (FMD). To analyze the antiviral effect, bovine thyroid and porcine kidney IBRS-2 cells and ICR mice were treated with Ad-HIFNalpha, Ad-PIFNbeta-IL18, and cocktail of Ad-HIFNalpha and Ad-PIFNbeta-IL18. The survival rate of suckling mice was monitored after foot and mouth disease virus (FMDV) challenge following intra-peritoneal (IP) administration of appropriate adenovirus. Indirect antigen ELISA was performed to evaluate inhibition of FMDV replication following challenge with the FMDV O, A, or Asia 1 serotypes in vitro. These recombinant adenoviruses reduced the replication of FMDV in susceptible cells, thereby decreasing the fatality in mice, suggesting that they can be a useful control method for the early protection against FMD infection in livestock after field trial.

Strategy for Novel Vaccine and Antivirals Against Foot-and-Mouth Disease

Foot-and-mouth disease (FMD) is a highly contagious, virally induced disease of cloven-hoofed animals. FMD-affected countries have suffered from a serious economic impact due to their decreased participation in the international livestock trade. Currently, disease control measures include inhibition of susceptible animal movement, slaughter of infected and susceptible in-contact animals, disinfection, and vaccination with an inactivated whole virus antigen. Researchers have attempted to develop new FMD vaccines to overcome the limitations of the current inactivated vaccine as well as new antivirals to more rapidly induce a protective response. In this study, we discuss the most effective novel FMD vaccines and antiviral strategies that are currently being studied. The vaccine research using subunits, synthetic peptides, DNA, cytokine-enhanced DNA, recombinant empty capsids, chimeric viruses, genetically engineered attenuated viruses, recombinant viral vectors, self-replicating DNA and transgenic plants expressing virus proteins is part of a trend towards novel FMD vaccine development. The antiviral methods using RNA interference (RNAi), RNAi-based recombinant adenoviruses and L(pro) or 3D(pol) inhibitors represent the current replication-inhibiting medicine used to control FMD.

Strategy for Novel Vaccine and Antivirals Against Foot-and-Mouth Disease

Foot-and-mouth disease (FMD) is a highly contagious, virally induced disease of cloven-hoofed animals. FMD-affected countries have suffered from a serious economic impact due to their decreased participation in the international livestock trade. Currently, disease control measures include inhibition of susceptible animal movement, slaughter of infected and susceptible in-contact animals, disinfection, and vaccination with an inactivated whole virus antigen. Researchers have attempted to develop new FMD vaccines to overcome the limitations of the current inactivated vaccine as well as new antivirals to more rapidly induce a protective response. In this study, we discuss the most effective novel FMD vaccines and antiviral strategies that are currently being studied. The vaccine research using subunits, synthetic peptides, DNA, cytokine-enhanced DNA, recombinant empty capsids, chimeric viruses, genetically engineered attenuated viruses, recombinant viral vectors, self-replicating DNA and transgenic plants expressing virus proteins is part of a trend towards novel FMD vaccine development. The antiviral methods using RNA interference (RNAi), RNAi-based recombinant adenoviruses and L(pro) or 3D(pol) inhibitors represent the current replication-inhibiting medicine used to control FMD.