Salmonella enterica serotype Choleraesuis infection in weaned pigs: a first clinicopathological case report from Korea

Salmonella enterica serotype Choleraesuis causes swine paratyphoid, with clinical findings of enterocolitis and septicemia. However, the clinicopathological features of S. Choleraesuis infections in pigs have not been reported in Korea. We describe the pathological findings of two weaned pigs with S. Choleraesuis infections, presenting with diarrhea, cough, and sudden death. Pathological examination indicated severe necrotic colitis in pig 1 and septicemic lesions in pig 2. Multidrug-resistant S. Choleraesuis was isolated from the pigs’ lungs and intestinal contents. Further research is required for the surveillance of S. Choleraesuis infections in pigs and the virulence estimation in the S. Choleraesuis isolates.

Klebsiella pneumoniae infection secondary to bovine viral diarrhea in two prematurely born calves

Abstract: This paper describes the development of neurological signs of two prematurely born calves four days after birth. The pathological examination results indicated fibrinopurulent polyserositis, including meningoencephalitis with suppurative bronchopneumonia. Bovine viral diarrhea virus subtype 2a was detected in most of the internal organs, and the bacterial colonies cultured from the samples were identified as Klebsiella (K.) pneumoniae. Molecular analysis via multilocus sequence typing identified a different K.pneumoniae isolate in each calf-type 14 in calf A and type 65 in calf B. This is the first report identifying K.pneumoniae sequence types 14 and 65 in cattle.

Survey of bovine norovirus infections from diarrheic calves in South Korea, 2015–2017

This study examined complex infections with various enteropathogens and the genetic diversity of bovine norovirus (BNoV) in 932 fecal samples from diarrheic calves in South Korea. Overall, seventeen (1.8%) of the samples tested positive for BNoV following RT-PCR examination. All BNoV-positive samples were co-infected with other intestinal pathogens, including bovine Rotavirus, Giardia, Cryptosporidium, and Escherichia coli. The genetic diversity of the BNoVs shared high nucleotide identity (98.1–99.5%) and amino acid homology (93.5–98.1%) with genotype 2 BNoV (GIII.2) strains. In conclusion, BNoV infections with GIII genotypes were detected in complex infections of diarrheic calves in South Korea.

Survey of bovine norovirus infections from diarrheic calves in South Korea, 2015–2017 / 대한수의학회지

This study examined complex infections with various enteropathogens and the genetic diversity of bovine norovirus (BNoV) in 932 fecal samples from diarrheic calves in South Korea. Overall, seventeen (1.8%) of the samples tested positive for BNoV following RT-PCR examination. All BNoV-positive samples were co-infected with other intestinal pathogens, including bovine Rotavirus, Giardia, Cryptosporidium, and Escherichia coli. The genetic diversity of the BNoVs shared high nucleotide identity (98.1–99.5%) and amino acid homology (93.5–98.1%) with genotype 2 BNoV (GIII.2) strains. In conclusion, BNoV infections with GIII genotypes were detected in complex infections of diarrheic calves in South Korea.

Co-infection of Dirofilaria immitis and Japanese encephalitis virus in a spotted seal (Phoca largha) in the Republic of Korea

A 10-year-old male spotted seal presented with loss of appetite and decreased activity. Grossly, the internal organs revealed several filarial nematodes in the right ventricle of the heart and the pulmonary vessels. Histopathological examination of the brain revealed moderate nonsuppurative meningoencephalitis with glial nodules and neuronophagia. Japanese encephalitis virus (JEV) of genotype I was isolated from the brain. All nematodes were identified as Dirofilaria immitis. This is the first clinical case of co-infection with D. immitis and JEV in a seal, suggesting that the seal, may be a dead-end host, like the human and horse, for JEV.

Analysis of Five Arboviruses and Culicoides Distribution on Cattle Farms in Jeollabuk-do, Korea

Arthropod-borne viruses (Arboviruses) are transmitted by arthropods such as Culicoides biting midges and cause abortion, stillbirth, and congenital malformation in ruminants, apparently leading to economic losses to farmers. To monitor the distribution of Culicoides and to determine their relationship with different environmental conditions (temperature, humidity, wind speed, and altitude of the farms) on 5 cattle farms, Culicoides were collected during summer season (May-September) in 2016 and 2017, and analyzed for identification of species and detection of arboviruses. About 35% of the Culicoides were collected in July and the collection rate increased with increase in temperature and humidity. The higher altitude where the farms were located, the more Culicoides were collected on inside than outside. In antigen test of Culicoides against 5 arboviruses, only Chuzan virus (CHUV) (2.63%) was detected in 2016. The Akabane virus (AKAV), CHUV, Ibaraki virus and Bovine ephemeral fever virus (BEFV) had a positive rate of less than 1.8% in 2017. In antigen test of bovine whole blood, AKAV (12.96%) and BEFV (0.96%) were positive in only one of the farms. As a result of serum neutralization test, antibodies against AKAV were generally measured in all the farms. These results suggest that vaccination before the season in which the Culicoides are active is probably best to prevent arbovirus infections.

Detection and genetic characterization of porcine circovirus 3 from aborted fetuses and pigs with respiratory disease in Korea

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.

Isolation and characterization of Korean porcine deltacoronavirus strain KNU16-07

Porcine deltacoronavirus (PDCoV) has emerged in several pig-raising countries and has been a causative pathogen associated with diarrheal diseases in South Korea since 2014. In the present study, we were able to isolate and cultivate a Korean PDCoV strain (KNU16-07) in cell culture and investigate its pathogenicity. PDCoV-inoculated piglets showed watery diarrhea accompanied by acute enteritis in the natural host. Sequencing analysis demonstrated the genetic stability of KNU16-07 for at least thirty serial passages.

Mass vaccination has led to the elimination of rabies since 2014 in South Korea

PURPOSE: Rabies is one of the most fatal diseases, but it is 100% preventable in animals by vaccination. In this study, we present the epidemiological features of, and national preventive measures against, rabies in Korea. MATERIALS AND METHODS: Data related to rabies and the population density of raccoon dogs in Korea were collected from the Animal and Plant Quarantine Agency, the Korean Centers for Disease Control and Prevention, and the National Institute of Environmental Research. Rabies diagnosis was confirmed with a fluorescent antibody test using brain samples of animals in accordance with the procedures described by the World Organization for Animal Health. Serological assays for dogs and cattle were conducted using the fluorescent antibody virus neutralization test. RESULTS: From 1993 to 2016, a total of seven human rabies cases and 437 animal rabies cases in five different species were reported. An increase in the distribution of bait vaccine seemed to be related to a dramatic decrease in rabies prevalence in endemic rabies regions. Two Korean provinces and the capital city, Seoul, were involved in rabies outbreaks. Korean rabies strains are most closely related to the eastern Chinese strain belonging to the Arctic-like lineage. The yearly seropositive rates ranged from 50.4% to 81.2% in dogs and from 25% to 60.5% in cattle residing in endemic rabies regions. CONCLUSION: This study indicates that national preventive measures, including mass vaccination and distribution of bait vaccines, have contributed to a substantial decrease in the number of rabies cases in Korea.

Development and evaluation of an immunochromatographic assay using a gp51 monoclonal antibody for the detection of antibodies against the bovine leukemia virus

Infection of cattle with bovine leukemia virus (BLV) has been observed and reported worldwide, including in Korea. The onsite identification of infected cattle would help decreasing and eradicating BLV infections on farms. Here, we present a new immunochromatographic assay that employs monoclonal antibodies (MAbs) for the detection of antibodies against BLV in the field. BLV envelope glycoprotein (gp)51 was expressed in E. coli, and MAbs against recombinant BLV gp51 were generated for the development of an immunochromatographic assay to detect BLV antibodies in cattle. The sensitivity and specificity of the assay were determined by comparing these results with those obtained from a standard enzyme linked immunosorbent assay (ELISA). A total of 160 bovine sera were used to evaluate the new immunochromatographic assay. Using ELISA as a reference standard, the relative specificity and sensitivity of this assay were determined to be 94.7% and 98%, respectively. Because of its high sensitivity and specificity, this BLV antibody detection assay would be suitable for the onsite identification of BLV infection in the field.

Genetic analysis of env and gag gene fragments of bovine leukemia virus identified in cattle from Korea / 대한수의학회지

Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis. This study was conducted to clarify the molecular characteristics of BLVs obtained from a specific region in Korea. Proviral BLVs were detected in anti-BLV antibody-positive blood samples by PCR. Env and gag fragments were sequenced and compared to previously published reference sequences. Analysis of the env gene sequence revealed that the YI strain was highly similar to genotype 1, including United States and Japanese strains. The gag gene sequence had the highest degree of similarity with a Japanese strain.

Isolation and characterization of orf viruses from Korean black goats

Five cases of orf virus infection in Korean black goats were diagnosed in our laboratory between 2010 and 2011. One orf virus (ORF/2011) was isolated from an ovine testis cell line (OA3.Ts) for use as a vaccine candidate. Sequences of the major envelope protein and orf virus interferon resistance genes were determined and compared with published reference sequences. Phylogenetic analyses revealed that orf viruses from Korean black goats were most closely related to an isolate (ORF/09/Korea) from dairy goats in Korea. This result indicates that the orf viruses might have been introduced from dairy goats into the Korean black goat population.

Outbreaks and Control of Animal Rabies in Korea / 감염과화학요법

Since rabies virus infection is fatal for both human and animals, the protective immunization by vaccines against animals is a critical importance for disease prevention and control. In Korea, recurrence of sylvatic rabies was reported in Gangwon province, which is the northern border area in 1993. During the years of 1994-2009, 417 animal rabies cases were registered in Gangwon and Gyeonggi provinces. The national animal rabies eradication program has performed to reduce rabies outbreaks by annual vaccination of dogs and cattle since 1995, and the oral vaccination of raccoon dogs with annual vaccinia-rabies glycoprotein (V-RG) bait vaccine. Additionally, serological surveillance on domestic animals has been executed since 1999 to monitor the anti-rabies antibody titers from Gangwon and Gyeonggi provinces where the vaccination campaign has been implemented.