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1.
Korean Journal of Veterinary Research ; : e1-2023.
Article in English | WPRIM | ID: wpr-1002464

ABSTRACT

Several outbreaks of Getah virus (GETV) have been reported in horses and pigs, causing large economic losses. However, there have been no reports describing serological survey for GETV in South Korea pigs. The present study conducted serological survey of GETV in South Korean pigs. A total of 670 whole blood samples were collected from domestic pigs. The overall seropositive rate was 26.4%, higher than the rates observed in racehorses in 2013–2014. Preparations for epidemics of novel diseases caused by climate change should include regular serological survey for these diseases, including GETV, and the development of vaccines against novel pathogens.

2.
Korean Journal of Veterinary Research ; : e5-2023.
Article in English | WPRIM | ID: wpr-1002460

ABSTRACT

Feline panleukopenia virus (FPV), feline calicivirus (FCV), and feline herpesvirus type-1 (FHV-1) are major infectious pathogens in cats. We evaluated the immunogenicity of a new vaccine containing inactivated FPV, two FCVs, and FHV-1 in animals. An FPV, two FCVs, and an FHV-1 isolate were continuously passaged 70, 50, 80, and 100 times in CRFK cells. FP70, FC50, FC80, and FH100 were propagated and used as vaccine antigens. Two inactivated feline virus vaccines, Rehydragel-adjuvanted vaccine (FRAV) and Cabopol-adjuvanted vaccine (FCAV) were prepared and inoculated into mice and guinea pigs. Humoral immune responses were measured using hemagglutination inhibition (HI) for FPV and virus-neutralizing antibody (VNA) for two FCVs and FHV-1 tests. Serial passages in CRFK cells resulted in increase in titers of FPV and two FCVs but not FHV-1 The FCAV induced higher mean HI and VNA titers than the FRAV in guinea pigs; therefore, the FCAV was selected. Cats inoculated with FCAV developed a mean HI titer of 259.9 against FPV, and VNA titers of 64, 256, and 3.2 against FCV17D03, FCV17D283, and FHV191071, respectively. Therefore, cats inoculated with the FCAV showed a considerable immune response after receiving a booster vaccination.

3.
Korean Journal of Veterinary Research ; : e13-2023.
Article in English | WPRIM | ID: wpr-1002452

ABSTRACT

Animals imported from abroad are a cause of rabies outbreaks in many countries. Therefore, rabies serology testing for dogs and cats traveling abroad is an important measure to reduce the incidence of rabies. Rabies virus antibodies were measured in sera collected from 2,367 dogs and 894 cats between 2017 and 2021. A serum sample with a value of 0.5 IU/mL or higher was considered a pass. The overall pass rates for rabies virus were 96.4% in dogs and 98.4% in cats. The mean rabies virus neutralization assay titers were higher in cats than in dogs and in female than in male animals. According to age, 6-year-old dogs and 9-year-old cats had the highest virus neutralization assay titers. Of the failure cases, 53.0% (53/100) were dogs or cats less than 1 year old. Although the average failure rates in dogs and cats were low at 3.5% and 1.6%, respectively, the factors influencing failure were age and vaccine manufacturer. Therefore, it is necessary to observe the vaccination interval and timing of blood collection after boosting.

4.
Korean Journal of Veterinary Research ; : e19-2023.
Article in English | WPRIM | ID: wpr-1002446

ABSTRACT

Rapid immunochromatography test (RICT) kits are commonly used for the diagnosis of canine parvovirus (CPV) because of their rapid turnaround time, simplicity, and ease of use. However, the potential for cross-reactivity and low sensitivity can yield false-positive or false-negative results. There are 4 genotypes of CPV. Therefore, evaluating the performance and reliability of RICT kits for CPV detection is essential to ensure accurate diagnosis for appropriate treatment. In this study, we evaluated the performance of commercial RICT kits in the diagnosis of all CPV genotypes. The cross-reactivity of 6 commercial RICT kits was evaluated using 8 dog-related viruses and 4 bacterial strains. The limit of detection (LOD) was measured for the 4 genotypes of CPV and feline panleukopenia virus. The tested kits showed no cross-reactivity with the 8 dog-related viruses or 4 bacteria. Most RICT kits showed strong positive results for CPV-2 variants (CPV-2a, CPV-2b, and CPV-2c). However, the 2 kits produced negative results for CPV-2 or CPV-2b at a titer of 105 FAID50/mL, which may result in inaccurate diagnoses. Therefore, some kits need to improve their LOD by increasing their binding efficiency to detect all CPV genotypes.

5.
Journal of Veterinary Science ; : e53-2023.
Article in English | WPRIM | ID: wpr-1001923

ABSTRACT

Background@#Mammalian orthoreovirus type 3 (MRV3), which is responsible for gastroenteritis in many mammalian species including pigs, has been isolated from piglets with severe diarrhea. However, the use of pig-derived cells as an infection model for swineMRV3 has rarely been studied. @*Objectives@#This study aims to establish porcine intestinal organoids (PIOs) and examine their susceptibility as an in vitro model for intestinal MRV3 infection. @*Methods@#PIOs were isolated and established from the jejunum of a miniature pig.Established PIOs were characterized using polymerase chain reaction (PCR) and immunofluorescence assays (IFAs) to confirm the expression of small intestine-specific genes and proteins, such as Lgr5, LYZI, Mucin-2, ChgA, and Villin. The monolayered PIOs and threedimensional (3D) PIOs, obtained through their distribution to expose the apical surface, were infected with MRV3 for 2 h, washed with Dulbecco’s phosphate-buffered saline, and observed. Viral infection was confirmed using PCR and IFA. We performed quantitative realtime reverse transcription-PCR to assess changes in viral copy numbers and gene expressions linked to intestinal epithelial genes and antiviral activity. @*Results@#The established PIOs have molecular characteristics of intestinal organoids. Infected PIOs showed delayed proliferation with disruption of structures. In addition, infection with MRV3 altered the gene expression linked to intestinal epithelial cells and antiviral activity, and these effects were observed in both 2D and 3D models. Furthermore, viral copy numbers in the supernatant of both models increased in a time-dependent manner. @*Conclusions@#We suggest that PIOs can be an in vitro model to study the infection mechanism of MRV3 in detail, facilitating pharmaceutical development.

6.
Korean Journal of Veterinary Research ; : e13-2021.
Article in English | WPRIM | ID: wpr-902556

ABSTRACT

Mammalian reovirus (MRV) causes respiratory and intestinal disease in mammals. Although MRV isolates have been reported to circulate in several animals, there are no reports on Korean MRV isolates from wildlife. We investigated the biological and molecular characteristics of Korean MRV isolates based on the nucleotide sequence of the segment 1 gene. In total, 144 swabs from wild animals were prepared for virus isolation. Based on virus isolation with specific cytopathic effects, indirect fluorescence assays, electron microscopy, and reverse transcription-polymerase chain reaction, one isolate was confirmed to be MRV. The isolate exhibited a hemagglutination activity level of 16 units with pig erythrocytes and had a maximum viral titer of 105.7 50% tissue culture infectious dose (TCID50)/mL in Vero cells at 5 days after inoculation. The nucleotide and amino-acid sequences of the partial segment S1 of the MReo2045 isolate were determined and compared with those of other MRV strains. The MReo2045 isolate had nucleotide sequences similar to MRV-3 and was most similar (96.1%) to the T3/Bat/Germany/342/08 strain, which was isolated in Germany in 2008. The MReo2045 isolate will be useful as an antigen for sero-epidemiological studies and developing diagnostic tools.

7.
Korean Journal of Veterinary Research ; : e19-2021.
Article in English | WPRIM | ID: wpr-902551

ABSTRACT

Feline panleukopenia virus (FPV) causes leukopenia and severe hemorrhagic diarrhea, killing 50% of naturally infected cats. Although intact FPV can serve as an antigen in the hemagglutination inhibition (HI) test, accidental laboratory-mediated infection a concern. A non-infectious diagnostic reagent is required for the HI test. Here, we expressed the viral protein 2 (VP2) gene of the FPV strain currently prevalent in South Korea in a baculovirus expression system; VP2 protein was identified by an indirect immunofluorescence assay, electron microscopy (EM), Western blotting (WB), and a hemagglutination assay (HA). EM showed that the recombinant VP2 protein self-assembled to form virus-like particles. WB revealed that the recombinant VP2 was 65 kDa in size. The HA activity of the recombinant VP2 protein was very high at 1:215. A total of 143 cat serum samples were tested using FPV (HI-FPV test) and the recombinant VP2 protein (HI-VP2 test) as HI antigens. The sensitivity, specificity, and accuracy of the HI-VP2 test were 99.3%, 88.9%, and 99.3%, respectively, compared to the HI-FPV test. The HI-VP2 and HI-FPV results correlated significantly (r = 0.978). Thus, recombinant VP2 can substitute for intact FPV as the serological diagnostic reagent of the HI test for FPV.

8.
Journal of Veterinary Science ; : e56-2021.
Article in English | WPRIM | ID: wpr-901426

ABSTRACT

Background@#Fluorescent antibody virus neutralization (FAVN) test is a standard assay for quantifying rabies virus-neutralizing antibody (VNA) in serum. However, a safer rabies virus (RABV) should be used in the FAVN assay. There is a need for a new method that is economical and time-saving by eliminating the immunostaining step. @*Objectives@#We aimed to improve the traditional FAVN method by rescuing and characterizing a new recombinant RABV expressing green fluorescent protein (GFP). @*Methods@#A new recombinant RABV expressing GFP designated as ERAGS-GFP was rescued using a reverse genetic system. Immuno-fluorescence assay, peroxidase-linked assay, electron microscopy and reverse transcription polymerase chain reaction were performed to confirm the recombinant ERAGS-GFP virus as a RABV expressing the GFP gene. The safety of ERAGS-GFP was evaluated in 4-week-old mice. The rabies VNA titers were measured and compared with conventional FAVN and FAVN-GFP tests using VERO cells. @*Results@#The virus propagated in VERO cells was confirmed as RABV expressing GFP.The ERAGS-GFP showed the highest titer (108.0TCID50/mL) in VERO cells at 5 days postinoculation, and GFP expression persisted until passage 30. The body weight of 4-week-old mice inoculated intracranially with ERAGS-GFP continued to increase and the survival rate was 100%. In 62 dog sera, the FAVN-GFP result was significantly correlated with that of conventional FAVN (r = 0.95). @*Conclusions@#We constructed ERAGS-GFP, which could replace the challenge virus standard-11 strain used in FAVN test.

9.
Clinical and Experimental Vaccine Research ; : 141-147, 2021.
Article in English | WPRIM | ID: wpr-913951

ABSTRACT

Purpose@#The aims of the present study were to evaluate the immunogenicity of an inactivated rabies vaccine based on the ERAGS strain @*Materials and Methods@#The ERAGS virus propagated in Vero cells was inactivated with 3 mM binary ethylenimine for 8 hours. Three types of inactivated rabies vaccines were prepared to determine the minimum vaccine virus titers. Four further types of inactivated rabies vaccines were prepared by blending inactivated ERAGS with four different adjuvants; each vaccine was injected into mice, guinea pigs, and dogs to identify the optimal adjuvant. The immunogenicity of a Montanide (IMS) gel-adjuvanted vaccine was evaluated in cats, dogs, and cattle. Humoral immune responses were measured via a fluorescent antibody virus neutralization method and a blocking enzyme-linked immunosorbent assay. @*Results@#The minimum virus titer of the inactivated rabies vaccine was over 107.0 50% tissue culture infectious doses (TCID50 values)/mL. Of the four kinds of adjuvants, the IMS gel-adjuvanted vaccine induced the highest mean viral neutralizing antibody (VNA) titers of 6.24 and 2.36 IU/mL in guinea pigs and dogs, respectively, and was thus selected as the vaccine for the target animals. Cats, dogs, and cattle inoculated with the IMS gel-adjuvanted vaccine developed protective VNA titers ranging from 3.5 to 1.2 IU/mL at 4 weeks post-inoculation (WPI). @*Conclusion@#Our data indicate that cats, dogs, and cattle inoculated with an inactivated rabies vaccine derived from the ERAGS strain developed protective immune responses that were maintained to 12 WPI.

10.
Korean Journal of Veterinary Research ; : e13-2021.
Article in English | WPRIM | ID: wpr-894852

ABSTRACT

Mammalian reovirus (MRV) causes respiratory and intestinal disease in mammals. Although MRV isolates have been reported to circulate in several animals, there are no reports on Korean MRV isolates from wildlife. We investigated the biological and molecular characteristics of Korean MRV isolates based on the nucleotide sequence of the segment 1 gene. In total, 144 swabs from wild animals were prepared for virus isolation. Based on virus isolation with specific cytopathic effects, indirect fluorescence assays, electron microscopy, and reverse transcription-polymerase chain reaction, one isolate was confirmed to be MRV. The isolate exhibited a hemagglutination activity level of 16 units with pig erythrocytes and had a maximum viral titer of 105.7 50% tissue culture infectious dose (TCID50)/mL in Vero cells at 5 days after inoculation. The nucleotide and amino-acid sequences of the partial segment S1 of the MReo2045 isolate were determined and compared with those of other MRV strains. The MReo2045 isolate had nucleotide sequences similar to MRV-3 and was most similar (96.1%) to the T3/Bat/Germany/342/08 strain, which was isolated in Germany in 2008. The MReo2045 isolate will be useful as an antigen for sero-epidemiological studies and developing diagnostic tools.

11.
Korean Journal of Veterinary Research ; : e19-2021.
Article in English | WPRIM | ID: wpr-894847

ABSTRACT

Feline panleukopenia virus (FPV) causes leukopenia and severe hemorrhagic diarrhea, killing 50% of naturally infected cats. Although intact FPV can serve as an antigen in the hemagglutination inhibition (HI) test, accidental laboratory-mediated infection a concern. A non-infectious diagnostic reagent is required for the HI test. Here, we expressed the viral protein 2 (VP2) gene of the FPV strain currently prevalent in South Korea in a baculovirus expression system; VP2 protein was identified by an indirect immunofluorescence assay, electron microscopy (EM), Western blotting (WB), and a hemagglutination assay (HA). EM showed that the recombinant VP2 protein self-assembled to form virus-like particles. WB revealed that the recombinant VP2 was 65 kDa in size. The HA activity of the recombinant VP2 protein was very high at 1:215. A total of 143 cat serum samples were tested using FPV (HI-FPV test) and the recombinant VP2 protein (HI-VP2 test) as HI antigens. The sensitivity, specificity, and accuracy of the HI-VP2 test were 99.3%, 88.9%, and 99.3%, respectively, compared to the HI-FPV test. The HI-VP2 and HI-FPV results correlated significantly (r = 0.978). Thus, recombinant VP2 can substitute for intact FPV as the serological diagnostic reagent of the HI test for FPV.

12.
Journal of Veterinary Science ; : e56-2021.
Article in English | WPRIM | ID: wpr-893722

ABSTRACT

Background@#Fluorescent antibody virus neutralization (FAVN) test is a standard assay for quantifying rabies virus-neutralizing antibody (VNA) in serum. However, a safer rabies virus (RABV) should be used in the FAVN assay. There is a need for a new method that is economical and time-saving by eliminating the immunostaining step. @*Objectives@#We aimed to improve the traditional FAVN method by rescuing and characterizing a new recombinant RABV expressing green fluorescent protein (GFP). @*Methods@#A new recombinant RABV expressing GFP designated as ERAGS-GFP was rescued using a reverse genetic system. Immuno-fluorescence assay, peroxidase-linked assay, electron microscopy and reverse transcription polymerase chain reaction were performed to confirm the recombinant ERAGS-GFP virus as a RABV expressing the GFP gene. The safety of ERAGS-GFP was evaluated in 4-week-old mice. The rabies VNA titers were measured and compared with conventional FAVN and FAVN-GFP tests using VERO cells. @*Results@#The virus propagated in VERO cells was confirmed as RABV expressing GFP.The ERAGS-GFP showed the highest titer (108.0TCID50/mL) in VERO cells at 5 days postinoculation, and GFP expression persisted until passage 30. The body weight of 4-week-old mice inoculated intracranially with ERAGS-GFP continued to increase and the survival rate was 100%. In 62 dog sera, the FAVN-GFP result was significantly correlated with that of conventional FAVN (r = 0.95). @*Conclusions@#We constructed ERAGS-GFP, which could replace the challenge virus standard-11 strain used in FAVN test.

13.
Journal of Bacteriology and Virology ; : 263-272, 2020.
Article in English | WPRIM | ID: wpr-898904

ABSTRACT

Feline herpesvirus type 1 (FHV-1) causes respiratory and ocular disease in cats.Although isolates of FHV-1 circulating in cats have been reported worldwide, Korean FHV-1 isolates and their features have not been reported thus far. We aimed to investigate the biological and molecular characterization of two FHV-1 isolates based on the nucleotide sequence of thymidine kinase (TK) and glycoprotein B (gB) gene. In total, 48 samples from 12 cats were prepared for virus isolation.For the diagnosis, virus isolation, indirect fluorescence assay (IFA), electron microscopy (EM), and polymerase chain reaction (PCR) and for the molecular characterization, cloning and sequencing were used. Based on many methods such as virus isolation with specific cytopathic effects, IFA, EM, and PCR, two isolates were confirmed as FHV-1 and they showed the highest viral titer (108.3 to 108.5 TCID50 /mL) in the Crandell–Rees Feline Kidney cells at 48 h after inoculation, but did not grow in MDCK and Vero cells. The nucleotide and amino acid sequences of the full TK and gB gene of FHV191071 and FHV191072 isolates were determined and compared with those of other herpesvirus strains. Two isolates possessed the same nucleotide sequences belonging to FHV-1 group and had the highest similarity (99.9%) with the KANS-02 strain, which was isolated from shelter in USA in 2016. Two isolates were confirmed as FHV-1 and they will be a useful basic resource for evaluating current FHV-1 vaccine and developing diagnostic tools.

14.
Korean Journal of Veterinary Research ; : 195-202, 2020.
Article in English | WPRIM | ID: wpr-902549

ABSTRACT

Feline calicivirus (FCV) infection results in a common upper respiratory disease associated with oral ulceration in cats.Although FCV infection has been reported in cats worldwide, the biologic and genetic features of South Korean FCV are unclear. We aimed to investigate the biological and genetic features of South Korean FCV isolates. Crandell-Rees feline kidney (CRFK) cells were used to isolate FCV from 58 organ homogenate samples. The FCV isolates were confirmed by cytopathic effects, immunofluorescence, electron microscopy, and reverse transcription polymerase chain reaction assays. Viral genetic analysis was carried out with VP2 gene and complete genomes of FCVs. Five viruses propagated in CRFK cells were confirmed to be FCVs. The FCV17D283 isolate showed the highest viral titer of 107.2TCID50 /mL at 36 h post-inoculation. Korean FCV isolates did not grow well in Vero, BHK-21, A72, or Madin-Darby canine kidney cells. The FCV17D03 and FCV17D283 isolates had the highest genetic similarity (80.1% and 86.9%) with the UTCVM-H1 and 14Q315 strains, which were isolated in the United States and South Korea in 1995 and 2014, respectively. We isolated five FCVs from cats and detected important genetic differences among them. FCV isolates did not show any virulent effects in mice.

15.
Korean Journal of Veterinary Research ; : 195-202, 2020.
Article in English | WPRIM | ID: wpr-894845

ABSTRACT

Feline calicivirus (FCV) infection results in a common upper respiratory disease associated with oral ulceration in cats.Although FCV infection has been reported in cats worldwide, the biologic and genetic features of South Korean FCV are unclear. We aimed to investigate the biological and genetic features of South Korean FCV isolates. Crandell-Rees feline kidney (CRFK) cells were used to isolate FCV from 58 organ homogenate samples. The FCV isolates were confirmed by cytopathic effects, immunofluorescence, electron microscopy, and reverse transcription polymerase chain reaction assays. Viral genetic analysis was carried out with VP2 gene and complete genomes of FCVs. Five viruses propagated in CRFK cells were confirmed to be FCVs. The FCV17D283 isolate showed the highest viral titer of 107.2TCID50 /mL at 36 h post-inoculation. Korean FCV isolates did not grow well in Vero, BHK-21, A72, or Madin-Darby canine kidney cells. The FCV17D03 and FCV17D283 isolates had the highest genetic similarity (80.1% and 86.9%) with the UTCVM-H1 and 14Q315 strains, which were isolated in the United States and South Korea in 1995 and 2014, respectively. We isolated five FCVs from cats and detected important genetic differences among them. FCV isolates did not show any virulent effects in mice.

16.
Journal of Bacteriology and Virology ; : 263-272, 2020.
Article in English | WPRIM | ID: wpr-891200

ABSTRACT

Feline herpesvirus type 1 (FHV-1) causes respiratory and ocular disease in cats.Although isolates of FHV-1 circulating in cats have been reported worldwide, Korean FHV-1 isolates and their features have not been reported thus far. We aimed to investigate the biological and molecular characterization of two FHV-1 isolates based on the nucleotide sequence of thymidine kinase (TK) and glycoprotein B (gB) gene. In total, 48 samples from 12 cats were prepared for virus isolation.For the diagnosis, virus isolation, indirect fluorescence assay (IFA), electron microscopy (EM), and polymerase chain reaction (PCR) and for the molecular characterization, cloning and sequencing were used. Based on many methods such as virus isolation with specific cytopathic effects, IFA, EM, and PCR, two isolates were confirmed as FHV-1 and they showed the highest viral titer (108.3 to 108.5 TCID50 /mL) in the Crandell–Rees Feline Kidney cells at 48 h after inoculation, but did not grow in MDCK and Vero cells. The nucleotide and amino acid sequences of the full TK and gB gene of FHV191071 and FHV191072 isolates were determined and compared with those of other herpesvirus strains. Two isolates possessed the same nucleotide sequences belonging to FHV-1 group and had the highest similarity (99.9%) with the KANS-02 strain, which was isolated from shelter in USA in 2016. Two isolates were confirmed as FHV-1 and they will be a useful basic resource for evaluating current FHV-1 vaccine and developing diagnostic tools.

17.
Journal of Veterinary Science ; : 721-724, 2018.
Article in English | WPRIM | ID: wpr-758839

ABSTRACT

A novel porcine circovirus 3 (PCV3) was first detected in pigs showing porcine dermatitis and nephropathy syndrome, reproductive failure, and multisystemic inflammation in the USA. Herein, we report on PCV3 as a potential etiological agent of clinical signs, reproductive failure and respiratory distress on Korean pig farms, based on in situ hybridization, pathological, and molecular findings. Confirmation of the presence of PCV3 may increase co-infection with other causative agents of disease in Korean pig herds, indicating the need for further systemic investigation of pathogenicity and of multiple infections with PCV2 genotypes and bacteria, and the development of an effective PCV3 vaccine.


Subject(s)
Aborted Fetus , Agriculture , Bacteria , Circovirus , Coinfection , Dermatitis , Genotype , In Situ Hybridization , Inflammation , Korea , Swine , Virulence
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