Molecular and serological surveillance of equine piroplasmosis in the Republic of Korea between 2016 and 2017

Equine piroplasmosis (EP) is caused by Babesia caballi and Theileria equi infection. We investigated antigen and antibody of EP in horses in the Republic of Korea during 2016-2017. Antigen and antibody of T. equi was detected 0.06% (1/1,650). Phylogenetic analysis of 18S rRNA revealed that the T. equi was highly homologous with the strains from China, Mongolia, and Spain. Two Theileria spp. were also detected and highly homologous with T. buffeli, T. luwehshuni, and T. orientalis.

Single-nucleotide polymorphismbased epidemiological analysis of Korean Mycobacterium bovis isolates

Background@#Bovine tuberculosis (TB) is caused by Mycobacterium bovis, a well-known cause of zoonotic tuberculosis in cattle and deer, and has been investigated in many physiological and molecular studies. However, detailed genome-level studies of M. bovis have not been performed in Korea. @*Objectives@#To survey whole genome-wide single-nucleotide polymorphism (SNP) variants in Korean M. bovis field isolates and to define M. bovis groups in Korea by comparing SNP typing with spoligotyping and variable number tandem repeat typing. @*Methods@#A total of 46 M. bovis field isolates, isolated from laryngopharyngeal lymph nodes and lungs of Korean cattle, wild boar, and Korean water deer, were used to identify SNPs by performing whole-genome sequencing. SNP sites were confirmed via polymerase chain reaction using 87 primer pairs. @*Results@#We identified 34 SNP sites with different frequencies across M. bovis isolates, and performed SNP typing and epidemiological analysis, which divided the 46 field isolates into 16 subtypes. @*Conclusions@#Through SNP analysis, detailed differences in samples with identical spoligotypes could be detected. SNP analysis is, therefore, a useful epidemiological tracing tool that could enable better management of bovine TB, thus preventing further outbreaks and reducing the impact of this disease.

Single-nucleotide polymorphismbased epidemiological analysis of Korean Mycobacterium bovis isolates

Background@#Bovine tuberculosis (TB) is caused by Mycobacterium bovis, a well-known cause of zoonotic tuberculosis in cattle and deer, and has been investigated in many physiological and molecular studies. However, detailed genome-level studies of M. bovis have not been performed in Korea. @*Objectives@#To survey whole genome-wide single-nucleotide polymorphism (SNP) variants in Korean M. bovis field isolates and to define M. bovis groups in Korea by comparing SNP typing with spoligotyping and variable number tandem repeat typing. @*Methods@#A total of 46 M. bovis field isolates, isolated from laryngopharyngeal lymph nodes and lungs of Korean cattle, wild boar, and Korean water deer, were used to identify SNPs by performing whole-genome sequencing. SNP sites were confirmed via polymerase chain reaction using 87 primer pairs. @*Results@#We identified 34 SNP sites with different frequencies across M. bovis isolates, and performed SNP typing and epidemiological analysis, which divided the 46 field isolates into 16 subtypes. @*Conclusions@#Through SNP analysis, detailed differences in samples with identical spoligotypes could be detected. SNP analysis is, therefore, a useful epidemiological tracing tool that could enable better management of bovine TB, thus preventing further outbreaks and reducing the impact of this disease.

Molecular and serological surveillance of equine piroplasmosis in the Republic of Korea between 2016 and 2017

Equine piroplasmosis (EP) is caused by Babesia caballi and Theileria equi infection. We investigated antigen and antibody of EP in horses in the Republic of Korea during 2016-2017. Antigen and antibody of T. equi was detected 0.06% (1/1,650). Phylogenetic analysis of 18S rRNA revealed that the T. equi was highly homologous with the strains from China, Mongolia, and Spain. Two Theileria spp. were also detected and highly homologous with T. buffeli, T. luwehshuni, and T. orientalis.

Pathological, immunohistochemical, and bacteriological findings in dogs infected with Brucella canis

This study describes pathological, immunohistochemical, and bacteriological findings in adult dogs and fetuses naturally infected with Brucella (B) canis. A total of 42 dogs including 40 dogs and 2 aborted fetuses were examined. The most common gross lesions in infected dogs were swelling of lymph nodes and spleen. The testes showed marked swelling with multifocal to diffuse reddish discoloration. The most significant histopathological lesions were observed in the placenta. Placental trophoblasts were markedly hypertrophied due to the accumulation of intra-cellular gram-negative bacteria. Lymphocytic inflammation of varying severity was observed in the reproductive organs such as male testis, epididymis, and prostate gland and female uterus. Strong immunolabelling was observed in the cytoplasm of most trophoblasts in the placental tissues using immunohistochemistry. However, immunohistochemical staining did not demonstrate any organisms in other organs of dogs and fetuses. B. canis isolates were most frequently obtained from the whole blood (82.5%) and superficial inguinal lymph node (77.5%) in both sexes. In addition, the isolation rate was higher in male genital organs than in those of females. Hence, management of male dogs is most important because infected dogs can play a role as carriers.

Seroprevalence and B1 gene Phylogeny of Toxoplasma gondii of Dogs and Cats in Republic of Korea

The outbreak of human toxoplasmosis can be attributed to ingestion of food contaminated with Toxoplasma gondii. Toxoplasmosis recently increased in domestic and stray dogs and cats. It prompted studies on the zoonotic infectious diseases transmitted via these animals. Sero- and antigen prevalences of T. gondii in dogs and cats were surveyed using ELISA and PCR, and B1 gene phylogeny was analyzed in this study. Toxoplasmosis antibodies were measured on sera of 403 stray cats, 947 stray dogs, 909 domestic cats, and 2,412 domestic dogs collected at nationwide regions, Korea from 2017 to 2019. In addition, whole blood, feces, and tissue samples were also collected from stray cats (1,392), stray dogs (686), domestic cats (3,040), and domestic dogs (1,974), and T. gondii-specific B1 gene PCR was performed. Antibody prevalence of stray cats, stray dogs, domestic cats, and domestic dogs were 14.1%, 5.6%, 2.3%, and 0.04%, respectively. Antigen prevalence of these animals was 0.5%, 0.2%, 0.1%, and 0.4%, respectively. Stray cats revealed the highest infection rate of toxoplasmosis, followed by stray dogs, domestic cats, and domestic dogs. B1 gene positives were 5 of stray cats, and identified to high/moderate pathogenic Type I/III group. These findings enforce that preventive hygienic measure should be strengthened at One Health level in dogs and cats, domestic and stray, to minimize human toxoplasmosis infections.

Recharacterization of the Canine Adenovirus Type 1 Vaccine Strain based on the Biological and Molecular Properties

Canine adenovirus type 1 (CAV-1) infection results in hepatitis in dogs. In this study, we investigated the biologic and genetic characteristics of the CAV-1 vaccine strain (CAV1V) to improve quality control about CAV vaccine. The identity of CAV1V as CAV-1 was confirmed based on its cytopathic effects and the results of hemagglutination (HA) and immunofluorescence assays, and electron microscopy. The CAV1V strain reached 10(7.5) TCID(50)/mL in MDCK cells at 4 days post-inoculation and exhibited hemmagglutination activity of 256 U using guinea pig erythrocytes. Intranuclear fluorescence in the infected cells was observed and typical adenoviruses were observed in electon microscope. CAV1V strain was identified as a CAV-1 strain by nucleotide sequence analysis. In a comparison of the nucleotide sequences of the fiber genes of several CAV strains, CAV1V showed the highest similarity (99.8%) with the GLAXO strain, which was isolated in Canada. Our biological characterization of CAV1V will facilitate quality control of the canine hepatitis vaccine.

Isolation and characterization of a new porcine epidemic diarrhea virus variant that occurred in Korea in 2014

Outbreaks of porcine epidemic diarrhea (PED) have resulted in significant economic losses in the swine industry, and another PED outbreak occurred in 2014 in Korea. Isolating and culturing PED virus (PEDV) allow investigations into its pathogenesis and the development of vaccines and diagnostic assays. In this study, we successfully isolated two PEDV isolates (QIAP1401 and QIAP1402) from naturally infected piglets at Jeju-do, Korea. Viral propagation was confirmed in Vero cells based on cytopathic effect, immunofluorescence assay, reverse transcription-polymerase chain reaction, and electron microscopic analyses. The QIAP401 isolate propagated well in Vero cells for 70 passages, with titers of 10(6.5) to 10(7.0) 50% tissue culture infectious dose/mL, which increased gradually with passaging. The nucleotide and amino acid sequences of the QIAP1401 isolate were determined and compared with those of other PEDV isolates. The QIAP1401 isolate was determined to be closely related to the USA/Minnesota271/2014 strain (> 99.9% nucleotide similarity) that was isolated in the USA in 2014. Phylogenetic analysis based on several PEDV genes suggested that a new PEDV variant is circulating in the Korean swine industry, with 93.08% similarity to the SM98 strain isolated in 1998. In addition, the QIAP1401 strain showed strong virulence in 3-day-old piglets and 11-week-old growing pigs.

Isolation and identification of canine adenovirus type 2 from a naturally infected dog in Korea / 대한수의학회지

Canine adenovirus type 2 (CAV-2) infection results in significant respiratory illness in dogs. Isolating and culturing CAV-2 allows for investigations into its pathogenesis and the development of vaccines and diagnostic assays. In this study, we successfully isolated a virus from a naturally infected dog in Gyeonggi-do, Korea. The virus was propagated in Madin-Darby canine kidney (MDCK) and Vero cells and showed a specific cytopathic morphology that appeared similar to a bunch of grapes. The virus was first confirmed as CAV-2 based on these cytopathic effects, an immunofluorescence assay, hemagglutination assay, and electron microscopy. The viral titer of the isolate designated APQA1601 reached 10(6.5) 50% tissue culture infections dose per mL in MDCK cells and exhibited no hemagglutination units with erythrocytes from guinea pig. The virus was also confirmed by polymerase chain reaction and next-generation sequencing. The APQA1601 strain had the highest similarity (~99.9%) with the Toronto A26/61 strain, which was isolated in Canada in 1976 when the nucleotide sequences of the full genome of the APQA1601 strain were compared with those of other CAV strains. Isolating CAV-2 will help elucidate the biological properties of CAV-2 circulating in Korean dogs.

Prevalence state of canine brucellosis in South Korea during 2015 and 2016 / 대한수의학회지

We investigated the prevalence of canine brucellosis in companion and stray dogs between March 2015 and December 2016 and determined the disease characteristics based on the geographic distribution, sex and age of the dogs in South Korea. We conducted a large-scale survey using serological and bacteriological tests. Samples were collected from 2,394 dogs (1,825 companions and 569 strays). Thirty (1.3%) samples were positive for Brucella canis antibodies including 16 (0.9%) from companion dogs and 14 (2.5%) from stray dogs. Two (1.0%) of the 196 samples cultured from the stray dogs were positive. When compared with male dogs, the female companion and stray dogs had a significantly higher prevalence of brucellosis. Moreover, the prevalence of canine brucellosis was significantly higher in stray dogs older than 6 years and the prevalence of the disease in companion dogs was highest in Incheon (2.1%) and Jeolla (2.1%) provinces. Stray dogs from the Daejeon metropolitan area had the highest prevalence of brucellosis (7.9%). National control measures for canine brucellosis have not previously been implemented. Our findings suggest that appropriate screening tests and control measures are necessary to improve the health of dogs and to protect public health in Korea, particularly with the rapid growth of the companion animal industry.

Prevalence state of canine brucellosis in South Korea during 2015 and 2016

We investigated the prevalence of canine brucellosis in companion and stray dogs between March 2015 and December 2016 and determined the disease characteristics based on the geographic distribution, sex and age of the dogs in South Korea. We conducted a large-scale survey using serological and bacteriological tests. Samples were collected from 2,394 dogs (1,825 companions and 569 strays). Thirty (1.3%) samples were positive for Brucella canis antibodies including 16 (0.9%) from companion dogs and 14 (2.5%) from stray dogs. Two (1.0%) of the 196 samples cultured from the stray dogs were positive. When compared with male dogs, the female companion and stray dogs had a significantly higher prevalence of brucellosis. Moreover, the prevalence of canine brucellosis was significantly higher in stray dogs older than 6 years and the prevalence of the disease in companion dogs was highest in Incheon (2.1%) and Jeolla (2.1%) provinces. Stray dogs from the Daejeon metropolitan area had the highest prevalence of brucellosis (7.9%). National control measures for canine brucellosis have not previously been implemented. Our findings suggest that appropriate screening tests and control measures are necessary to improve the health of dogs and to protect public health in Korea, particularly with the rapid growth of the companion animal industry.

Isolation and identification of canine adenovirus type 2 from a naturally infected dog in Korea

Canine adenovirus type 2 (CAV-2) infection results in significant respiratory illness in dogs. Isolating and culturing CAV-2 allows for investigations into its pathogenesis and the development of vaccines and diagnostic assays. In this study, we successfully isolated a virus from a naturally infected dog in Gyeonggi-do, Korea. The virus was propagated in Madin-Darby canine kidney (MDCK) and Vero cells and showed a specific cytopathic morphology that appeared similar to a bunch of grapes. The virus was first confirmed as CAV-2 based on these cytopathic effects, an immunofluorescence assay, hemagglutination assay, and electron microscopy. The viral titer of the isolate designated APQA1601 reached 10(6.5) 50% tissue culture infections dose per mL in MDCK cells and exhibited no hemagglutination units with erythrocytes from guinea pig. The virus was also confirmed by polymerase chain reaction and next-generation sequencing. The APQA1601 strain had the highest similarity (~99.9%) with the Toronto A26/61 strain, which was isolated in Canada in 1976 when the nucleotide sequences of the full genome of the APQA1601 strain were compared with those of other CAV strains. Isolating CAV-2 will help elucidate the biological properties of CAV-2 circulating in Korean dogs.

Incidence and Sero-survey of Canine Adenovirus Type 2 in Various Animal Species

Canine adenovirus type 2 (CAV-2) is the cause of a major respiratory illness in dogs. In this study, we analyzed adenovirus infections in dogs using 2000–2017 data from the Animal and Plant Quarantine Agency (APQA) and conducted a serological survey of CAV-2 infection in six animal species in Korea. In total, 38 of the 3,179 dog samples were confirmed as canine adenovirus infections. In serological survey, 1,028 dog sera, 160 raccoon dog sera, 100 cattle sera, 257 sow sera, 206 horse sera, and 106 cat sera, collected from January 2016 to July 2018, were screened for the presence of anti-CAV-2 antibodies by virus neutralization test. The seropositivity rates for dogs, raccoon dogs, cattle, sows, horses, and cats were 88.5% (910/1,028), 51.3% (82/160), 85.0% (85/100), 48.6% (125/257), 35.0% (72/206), and 2.8% (3/106), respectively. Among dogs and raccoon dogs, 1.9% (20/1,028) and 8.8% (14/160), respectively, had a virus-neutralizing antibody (VNA) titer of over 1:256. A high CAV-2 VNA titer indicates a repeated vaccination or natural infection in Korean dogs and circulation of CAV-2 in raccoon dog populations.

Isolation and identification of Moraxella cuniculi from a rabbit with keratoconjunctivitis

A Gram-negative, catalase- and oxidase-positive, coccus-shaped bacterium was isolated from a rabbit with keratoconjunctivitis. Colonies of the isolate were round, smooth, and exhibited hemolytic activity on 5% sheep blood agar. Scanning electron microscopy revealed 0.4 to 0.5 µm diameter oval cocci. Partial 16S rRNA gene (1446 bp) sequence analysis demonstrated the isolate had significant homology with the Moraxella cuniculi CCUG2154 strain isolated from a rabbit in Germany in 1973. Our isolate was designated as APQAB1701. Antibiotic susceptibility tests demonstrated that APQAB1701 was sensitive to 24 antibiotics; 3 of the antibiotics (nalidixic acid, spectinomycin, and colistin) had minimal inhibitory concentrations ≥ 32 µg/mL against the isolate.

Porcine ear necrosis syndrome by coinfection of porcine reproductive and respiratory syndrome virus and Staphylococcus hyicus

Porcine ear necrosis syndrome is characterized by erosive and ulcerative lesions at the margin or tip of the pinna. Three growing pigs of different ages exhibited retarded growth accompanied by reddening and necrosis of ear prior to death. Gross examination showed reddening, swelling, black discoloration, scaling, and variable-sized yellowish materials and edema in ear cross section. Microscopically, thrombosis, abscess, ulceration, epidermal hyperplasia, and dermal pyogranulomatous inflammation with an intralesional bacterial colony were observed. Staphylococcus hyicus was isolated in all pigs' ears and porcine reproductive and respiratory syndrome virus was detected by PCR and immunohistochemistry.

Congenital systemic melanosis in a black mongrel pig / 대한수의학회지

Four 3-day-old piglets with retarded growth were submitted to the Animal and Plant Quarantine Agency for diagnosis. Necropsy showed that one piglet had black spots ranging from 2 mm to 1 cm in diameter in the cerebellum, lungs, regional lymph nodes, and cecum. Histological findings were consistent with the gross appearance in which melanin pigmentation was observed in the organs mentioned above. Based on Fontana-Masson staining, we diagnosed this animal with systemic melanosis. To the best of our knowledge, this is the first case of systemic melanosis in black breeds of swine in Korea.

A case of malignant dysgerminoma in a slaughtered dairy cow / 대한수의학회지

An abnormally enlarged right ovary and a mass in fat surrounding the right kidney were discovered in a dairy cow during routine postmortem examination at slaughter. The ovary was dark reddish and multinodular in shape. Numerous cystic structures were identified in the mass. Histopathologically, the ovary was completely replaced with large, uniform, polyhedral neoplastic cells containing vesicular nuclei and prominent nucleoli. The mitotic index was high. In the lymphatic vessels, tumor emboli were observed. Another mass in the fat surranding the right kidney had the same histological features as the ovarian mass. This animal was diagnosed with malignant dysgerminoma and metastasis to other peritoneal organs.

Epitheliogenesis imperfecta in a bovine fetus of Korean native cattle / 대한수의학회지

In this study, we describe a case of epitheliogenesis imperfecta (EI) observed in the fetus of Korean native cattle. The fetus had multifocal areas of skin defect, especially on the distal portions of the four limbs, and the affected areas were bright-red and glistening. Histopathologically, these areas were characterized by complete absence of squamous epithelium, infiltration of inflammatory cells into the dermis, atrophy of hair follicles, sebaceous and sweat glands. To the best of our knowledge, this is the first report of epitheliogenesis imperfecta in Korean native cattle.

Devastating endosulfan poisoning in Korean native cattle / 대한수의학회지

Here, we report the poisoning case of 10 cows. Several distinct clinical signs such as convulsion, excessive salivation, circling, lateral recumbency, and death were observed. Necropsy and histopathological examination did not reveal any significant abnormal findings. Moreover, no bacteria or viruses were detected in tissue, blood, and feeding food. However, endosulfan was detected from the stomach contents and microbials. Our results strongly suggest that death of cows may be closely associated with endosulfan poisoning.

Case report of Johne's disease in Korean black goat (Capra hircus aegagrus) / 대한수의학회지

Two Korean black goat (approx. 2 and 3 years old) showing diarrhea and chronic weight loss were submitted to Animal and Plant Quarantine Agency. At necropsy, there were thickening of small intestine and enlargement of mesenteric lymph nodes. Microscopically, they had granulomatous enteritis in the small and large intestine and granulomatous lymphadenitis. By polymerase chain reaction (PCR) and acid fast stain, strong positive reaction and acid-fast rod bacteria were detected. According to the result of histopathology and PCR, we confirmed this case as Johne's disease. As far as we know, this is the first report of Johne's disease in Korean black goat.