The first reported hepatitis E outbreak in a food manufacturing factory: Korea, 2022

Objectives@#On February 16, 2022, 12 cases of hepatitis E virus (HEV) infection were reported in a food manufacturing factory in Korea. The aim of this study was to identify additional cases and to determine the source of this HEV outbreak. @*Methods@#This study was an in-depth investigation of 12 HEV immunoglobulin M (IgM)-positive cases and their demographic, clinical, and epidemiological characteristics. On-site specimens were collected from the environment and from humans, and a follow-up investigation was conducted 2 to 3 months after the outbreak. @*Results@#Among 80 production workers in the factory, 12 (15.0%) had acute HEV infection, all of whom were asymptomatic. The follow-up investigation showed that 3 cases were HEV IgM-positive, while 6 were HEV IgG-positive. HEV genes were not detected in the HEV IgM-positive specimens. HEV genes were not detected in the food products or environmental specimens collected on-site. HEV was presumed to be the causative pathogen. However, it could not be confirmed that the source of infection was common consumption inside the factory. @*Conclusion@#This was the first domestic case of an HEV infection outbreak in a food manufacturing factory in Korea. Our results provide information for the future control of outbreaks and for the preparation of measures to prevent domestic outbreaks of HEV infection.

The laboratory test procedure to confirm rotavirus vaccine infection in severe complex immunodeficiency patients

The rotavirus vaccine is a live vaccine, and there is a possibility of infection by the virus strain used in the vaccine. We investigated the process of determining whether an infection was caused by the vaccine strain in a severe complex immunodeficiency (SCID) patient with rotavirus infection. The patient was vaccinated with RotaTeq prior to being diagnosed with SCID. The testing process was conducted in the following order: confirming rotavirus infection, determining its genotype, and confirming the vaccine strain. Rotavirus infection was confirmed through enzyme immunoassay and VP6 gene detection. G1 and P[8] were identified by multiplex polymerase chain reaction for the genotype, and G3 was further identified using a single primer. By detecting the fingerprint gene (WC3) of RotaTeq, it was confirmed that the detected virus was the vaccine strain. Genotypes G1 and P[8] were identified, and the infection was suspected of having been caused by rotavirus G1P[8]. G1P[8] is the most commonly detected genotype worldwide and is not included in the recombinant strains used in vaccines. Therefore, the infection was confirmed to have been caused by the vaccine strain by analyzing the genetic relationship between VP4 and VP7. Rotavirus infection by the vaccine strain can be identified through genotyping and fingerprint gene detection. However, genetic linkage analysis will also help to identify vaccine strains.

The laboratory test procedure to confirm rotavirus vaccine infection in severe complex immunodeficiency patients

The rotavirus vaccine is a live vaccine, and there is a possibility of infection by the virus strain used in the vaccine. We investigated the process of determining whether an infection was caused by the vaccine strain in a severe complex immunodeficiency (SCID) patient with rotavirus infection. The patient was vaccinated with RotaTeq prior to being diagnosed with SCID. The testing process was conducted in the following order: confirming rotavirus infection, determining its genotype, and confirming the vaccine strain. Rotavirus infection was confirmed through enzyme immunoassay and VP6 gene detection. G1 and P[8] were identified by multiplex polymerase chain reaction for the genotype, and G3 was further identified using a single primer. By detecting the fingerprint gene (WC3) of RotaTeq, it was confirmed that the detected virus was the vaccine strain. Genotypes G1 and P[8] were identified, and the infection was suspected of having been caused by rotavirus G1P[8]. G1P[8] is the most commonly detected genotype worldwide and is not included in the recombinant strains used in vaccines. Therefore, the infection was confirmed to have been caused by the vaccine strain by analyzing the genetic relationship between VP4 and VP7. Rotavirus infection by the vaccine strain can be identified through genotyping and fingerprint gene detection. However, genetic linkage analysis will also help to identify vaccine strains.

Outbreak associated with Rotavirus G11,P25 in Korea in 2018 / 감염과화학요법

We here report the first outbreak caused by rotavirus G11,P[25] in Korea in 2018, representing a case of re-assortment with pig-derived rotavirus. The genotype constellation was identical to the virus identified in Korea in 2012 as G11-P[25] -I12-R1-C1-M1-A1-N1-T1-E1-H1. The infection source was not known exactly but it must be considered infection from swine.

Outbreak associated with Rotavirus G11,P25 in Korea in 2018 / 감염과화학요법

We here report the first outbreak caused by rotavirus G11,P[25] in Korea in 2018, representing a case of re-assortment with pig-derived rotavirus. The genotype constellation was identical to the virus identified in Korea in 2012 as G11-P[25] -I12-R1-C1-M1-A1-N1-T1-E1-H1. The infection source was not known exactly but it must be considered infection from swine.

An Outbreak Associated with Sapovirus GI.3 in an Elementary School in Gyeonggi-do, Korea

On October 4, 2018, an outbreak of gastroenteritis associated with sapovirus occurred among elementary school students in Gyeonggi-do, Korea. Epidemiologic studies were conducted in a retrospective cohort approach. Using self-administered questionnaires, we collected information on symptoms and food items consumed. Of the 999 subjects, 17 developed patients that met the case definition. The main symptom was vomiting (100%), and the symptomatic age was 6-12 years. Positive samples were identified by conventional reverse transcription polymerase chain reaction for sequencing. They were classified into genotype GI.3 by phylogenetic analysis. This is the first report of an outbreak associated with sapovirus GI.3 in Korea.

Emergence of Norovirus GII.17-associated Outbreak and Sporadic Cases in Korea from 2014 to 2015

Human norovirus are major causative agent of nonbacterial acute gastroenteritis. In general, genogroup (G) II.4 is the most prominent major genotype that circulate in human population and the environment. However, a shift in genotypic trends was observed in Korea in December 2014. In this study, we investigated the trend of norovirus genotype in detail using the database of Acute Diarrhea Laboratory Surveillance (K-EnterNet) in Korea. GII.17 has since become a major contributor to outbreaks of norovirus-related infections and sporadic cases in Korea, although the reason for this shift remain unknown.

First Report of Salmonella Serotype Tilene Infection in Korea / 대한임상미생물학회지

Salmonellosis is a common food- and water-borne disease and is also a major zoonosis. Currently, the isolation of rare Salmonella serotypes is increasing every year in Korea. Among them, the Salmonella serotype Tilene was first isolated from two people who visited a hospital located in Andong-si in 2013. Clinical symptoms were weak or non-existent. There was no clear epidemiological connection between the two cases. However, it was assumed that both were independently exposed to a single infectious agent. Perhaps due to their geographical proximity, molecular epidemiological analysis showed the same result between the isolated strains. This serotype has increasingly reported an association with hedgehogs. Recently, the importation of exotic animals, including hedgehogs, as pets has been gradually increasing. Thus, it is recommended that high-risk groups avoid contact with exotic pets.

Modified Method of Multilocus Sequence Typing (MLST) for Serotyping in Salmonella Species

Multilocus sequence typing (MLST) of Salmonella is useful method for replacing serotyping using antisera but is limited by difficulties associated with in polymerase chain reaction (PCR). We optimized the PCR reaction, especially annealing temperature and extension time (94degrees C for 2 min; 40 cycles at 94degrees C for 30 sec, 56.8degrees C for 1 min, 72degrees C for 2 min; and 72degrees C for 10 min). The degradation of PCR product by thermostable nucleases was inhibited by using template DNAs treated proteinase K or purified by a commercialized preparation kit. The resulting modified MLST was used as accurate and fast typing method.

Human Infection of Salmonella Matadi in Korea

No abstract available.

Genetic Characteristics and Relatedness of Imported Vibrio cholerae O1 Biotype El Tor in Korea / 대한임상미생물학회지

BACKGROUND: Cholera is a representative water-borne disease that is caused by V. cholera ctx (+). V. cholera El Tor was previously the primary pathogen, but after the seventh pandemic outbreak, it was replaced by a V. cholera El Tor variant with a classical phenotype and genotype. In this study, we investigated the genotypic and phenotypic characteristics of imported V. cholerae El Tor in Korea. METHODS: Forty-nine V. cholerae O1 El Tor strains isolated from 2004 to 2011 were used in this study. Polymerase chain reaction amplification of the ctxB and rstR genes was used for biotype determination. An antimicrobial susceptibility test was performed for phenotypic analysis, and pulse field gel electrophoresis (PFGE) was used for analysis of genetic relatedness. RESULTS: Classical ctxB genes were found in all of the isolates, while classical, El Tor, and combined rstR genes were found. Twenty strains showed antimicrobial resistance against streptomycin, sulfamethoxazole/trimethoprim, nalidixic acid, and ciprofloxacin. Based on PFGE, all isolates were grouped as cluster B. The country of origin and resistance pattern were highly related, although the time of influx and serogroup were not. CONCLUSION: Isolates of V. cholera El Tor imported since 2004 were hybrids of V. cholera El Tor, which has the classical ctxB gene and is considered to be a CTX prophage. The SXT element plays an important role in antimicrobial resistance. PFGE patterns, which can be used for analysis of imported V. cholera, revealed the relatedness of the resistant isolates.

First isolation of Salmonella I 4,5,12:i:- from domestic animals in Korea / 대한수의학회지

Salmonella I 4,[5],12:i:- was a monophasic variant of Salmonella (S.) Typhimurium and notorious for re-emerging candidate which would replace S. Typhimurium DT104 for antibiotic resistance. Recently, isolation rate was increased on human and industrial animals but there was no case in domestic animals but human in Korea. This was first isolation case from domestic animals in Korea. The five isolates from feces of duck (n = 3), chicken (n = 1), and wild bird (n = 1) showed antibiotic resistance against cephems and aminoglycosides. These means that the spread of emerging bacterial pathogens to domestic animals and the need of systemic management for Salmonella I 4,[5],12:i:-.

Epidemic by Salmonella I 4,5,12:i:- and Characteristics of Isolates in Korea / 감염과화학요법

BACKGROUND: Salmonella I 4,[5],12:i:- was first reported as a new serovar by the Spanish National Reference Laboratory in 1997. Thereafter, several outbreaks caused by this serovar have been reported, indicating worldwide transmission. MATERIALS AND METHODS: Stool samples and patient data were collected from diarrhea cases in an outbreak at Daegu city in 2008. Salmonella isolates were characterized by phage typing, antibiotic resistance profile and flagella gene deletion. Deposited isolates in the EnterNet-Korea, acute diarrheal surveillance system, were also screened for this serovar. RESULTS: Isolates from diarrhea patients in the Daegu outbreak (2008) were identified as Salmonella I 4,[5],12:i:-. Screening the deposited isolates in the EnteroNet-Korea revealed that an unidentifed isolate in 2001 was the Salmonella I 4,[5], 12:i:-. CONCLUSIONS: Salmonella I 4,[5],12:i:-. was the causative pathogen of the 2008 foodborne outbreak of salmonellosis in Daegu City. Retrospective screening revealed that Salmonella I 4,[5],12:i:- was present in Korea as early as 2001.

Further Evaluation of Multiplex PCR for Rapid Detection of Salmonella Typhi / 감염과화학요법

Typhoid fever is a class I legally designated communicable disease in Korea; and if remains as an important public health problem in many developing countries. It takes at least 3-5 days to detect and identify Salmonella Typhi (S. Typhi) by classical diagnostic method. For this reason, multiplex PCR (mPCR) was evaluated in detecting and identifying S. Typhi. In this study, forty-three bacterial strains, which consisted of 42 Salmonella enterica serovars and one Citrobacter freundii. were used to evaluate the promptness of mPCR in detecting and identifying S. Typhi. mPCR was performed with four genes which were known for representing Salmonella spp and/or S. Typhi: invA, fliC-d, viaB and prt. invA and prt gene was amplified in all strains and viaB gene was in only S. Typhi. fliC-d gene was amplified in three serovars: S. Typhi, S. Schwarzengrund and S. Livingstone. After specificity test, mPCR was modified as triplex PCR with three genes (invA, fliC-d, and viaB) and the sensitivity test was performed against S. Typhi-inoculated stool samples. mPCR was able to detect S. Typhi cell suspension of 1x105 cfu/mL. We found that modified multiplex PCR was useful to detect S. Typhi from stool samples within 24h whereas it takes 3-5days to detect by classic diagnosis method.

Infection Status of Hospitalized Diarrheal Patients with Gastrointestinal Protozoa, Bacteria, and Viruses in the Republic of Korea

To understand protozoan, viral, and bacterial infections in diarrheal patients, we analyzed positivity and mixed-infection status with 3 protozoans, 4 viruses, and 10 bacteria in hospitalized diarrheal patients during 2004-2006 in the Republic of Korea. A total of 76,652 stool samples were collected from 96 hospitals across the nation. The positivity for protozoa, viruses, and bacteria was 129, 1,759, and 1,797 per 10,000 persons, respectively. Especially, Cryptosporidium parvum was highly mixed-infected with rotavirus among pediatric diarrheal patients (29.5 per 100 C. parvum positive cases), and Entamoeba histolytica was mixed-infected with Clostridium perfringens (10.3 per 100 E. histolytica positive cases) in protozoan-diarrheal patients. Those infected with rotavirus and C. perfringens constituted relatively high proportions among mixed infection cases from January to April. The positivity for rotavirus among viral infection for those aged or = 50 years. The information for association of viral and bacterial infections with enteropathogenic protozoa in diarrheal patients may contribute to improvement of care for diarrhea as well as development of control strategies for diarrheal diseases in Korea.

Enhancement of protective immune responses by oral vaccination with Saccharomyces cerevisiae expressing recombinant Actinobacillus pleuropneumoniae ApxIA or ApxIIA in mice

We previously induced protective immune response by oral immunization with yeast expressing the ApxIIA antigen. The ApxI antigen is also an important factor in the protection against Actinobacillus pleuropneumoniae serotype 5 infection; therefore, the protective immunity in mice following oral immunization with Saccharomyces cerevisiae expressing either ApxIA (group C) or ApxIIA (group D) alone or both (group E) was compared with that in two control groups (group A and B). The immunogenicity of the rApxIA antigen derived from the yeast was confirmed by a high survival rate and an ApxIA-specific IgG antibody response (p < 0.01). The highest systemic (IgG) and local (IgA) humoral immune responses to ApxIA and ApxIIA were detected in group E after the third immunization (p < 0.05). The levels of IL-1beta and IL-6 after challenge with an A. pleuropneumoniae field isolate did not change significantly in the vaccinated groups. The level of TNF-alpha increased in a time-dependent manner in group E but was not significantly different after the challenge. After the challenge, the mice in group E had a significantly lower infectious burden and a higher level of protection than the mice in the other groups (p < 0.05). The survival rate in each group was closely correlated to the immune response and histopathological observations in the lung following the challenge. These results suggested that immunity to the ApxIA antigen is required for optimal protection.

Biological characteristics of Chinese hamster ovary cells transfected with bovine Prnp

A normal prion protein (PrPc) is converted to a proteaseresistant isoform by an apparent self-propagating activity in transmissible spongiform encephalopathy, a neurodegenerative disease. The cDNA encoding open reading frame (ORF) of the bovine prion protein gene (Prnp) was cloned from Korean cattle by PCR, and was transfected into Chinese hamster ovary (CHO-K1) cells using lipofectamine. The gene expression of the cloned cDNA was confirmed by RT-PCR and Western blotting with the monoclonal antibody, 6H4. Cellular changes in the transfected CHO-K1 cells were investigated using parameters such as MTT, lactate dehydrogenase (LDH), and superoxide dismutase (SOD) activities, as well as nitric oxide (NO) production, and an apoptosis assay. In the MTT and LDH assays, the bovine PrnP-transfectant showed a lower proliferation rate than the wild-type (p < 0.05). Production of NO, after LPS or ConA stimulation, was not detected in either transfectants or CHO-K1 cells. In SOD assay under ConA stimulation, the SOD activity of transfectants was 10 times higher than that of CHO-K1 cells at 6 h after treatment (p < 0.05). The genomic DNA of both the transfectants and control cells began to be fragmented at 6 h after treatment with cyclohexamide. Caspase-3 activity was reduced by transfection with the bovine Prnp (p < 0.05). Conclusively, the viability of transfectants expressing exogenous bovine Prnp was decreased while the capacities for cellular protection against antioxidative stress and apoptosis were increased.

Changes in patterns of antimicrobial susceptibility and class 1 integron carriage among Escherichia coli isolates

The worldwide use of antimicrobials in different fields has created enormous pressure for the selection of resistance among opportunistic bacterial pathogen. One hundred four E. coli isolates were collected and identified from swine with diarrhea in Korea during the period of 2002. The isolates showed highly resistant to streptomycin (99. 0%), tetracycline (97. 1%), neomycin (91. 3%)and carbenicillin (84. 6%)in antimicrobial susceptibility test. Moreover, all of the isolates showed multiple antimicrobial resistant to more than 3, and 85%of them were resistant to more than 7 of total 14 antimicrobial agents. In comparison with isolates in 1998, resistance to antimicrobials was more frequent among the isolates in 2002. Presence of class 1 integrons was investigated through amplification of the gene with PCR, and could be classified 8 groups by pattern of 4 different amplicons. Class 1 integrons were observed in 67 strains (64. 2%)of E. coli from swine in Korea. One and 1. 6 kbp of amplicons were revealed to contain aadA1 and aadB-aadA1 gene cassettes respectively. Two kbp of amplicon had three different gene cassettes, dhfrXII-orfF-aadA2, and 3. 0 kbp of amplicon includes aadB-cmlA1 gene cassettes.

A predictive model for the level of sIgA based on IgG levels following the oral administration of antigens expressed in Sacchromyces cerevisiae

Oral vaccination may be the most efficient way of inducing an immune response at the remote mucosal site through the common mucosal immune network. Antigenspecific secretory IgA (sIgA) is the major immunoglobulin type generally detected in the secretions of experimental animals following an effective oral immunization. Actinobacillus pleuropneumoniae causing disease in the lung of pig initially interacts, colonizes, and infects the host tissues at the mucosal surface of the respiratory tract. Also, importantly for A. pleuropneumoniae protection, the quantity of sIgA in the lung had merits associated with the mucosal immunity. However, there is no simple method to monitor the level of sIgA as an indicator for the induction of local immune responses by an oral vaccination in the target tissue. Therefore, the relationship between sIgA and IgG was analyzed to evaluate the induction of local immune responses by an oral immunization with Saccharomyces cerevisiae expressing the apxIA and apxIIA genes of A. pleuropneumoniae in this study. The correlation coefficient of determination (r2 x 100) for paired samples in both vaccinated and control groups showed a significant positive-relationship between IgG in sera and sIgA in the lung or intestine. These results indicated that IgG antibody titers in sera could be useful to indirectly predict local immune response, and sIgA, in the lung or intestine to evaluate the efficacy of an oral vaccination.

Development of a novel antigen capture-ELISA using IgY against porcine interleukin-6 and its application

Interleukin-6 (IL-6) is introduced as a marker of disease. At present, a variety of method may be used to quantify expression of this protein. Antigen capture-ELISA is a sensitive and accurate quantification method previously used with ovine, rat, and human IL-6 proteins. However, it has never been reported to quantify porcine IL-6 protein using capture ELISA. In this study, we generated and characterized a set of IgY and mono-specific polyclonal antibodies to recombinant porcine IL-6 (rpIL-6), and combining these with a sensitive and specific capture-ELISA for a diagnostic purpose. cDNA encoding the mature protein coding region of porcine IL-6 was cloned and expressed with pQE-30UA expression vector. rpIL-6 was then expressed and purified by using Ni-NTA resin. Protein mass of 24 kDa was found with SDS-PAGE and the identity of the protein was confirmed by Western-blot. Production of polyclonal antibodies against rpIL-6 was performed using the purified rpIL-6 in mice and hens. An antigen capture-ELISA was developed with the antibodies after their extraction. To compare the IL-6 level in the different sanitary state of farms, pig sera were randomly collected and concentration of IL-6 in the sera was measured with the antigen capture-ELISA. The capture-ELISA with the optimal concentration of antibodies, in this study, was able to detect about 10 ng/ml of rpIL-6. IL-6 levels determined with the capture-ELISA in pig sera showed positive correlation with the sanitary states of the farms. These results suggested that the developed antigen capture-ELISA could be a good tool for the screening of microbial infection in pig farms.