Sung Soon Kim

Messenger RNA (mRNA) vaccination was developed to mitigate the coronavirus disease 2019 pandemic. However, data on antibody kinetics and factors influencing these vaccines’ immunogenicity are limited. We conducted a prospective study on healthy young adults who received two doses of the mRNA-1273 vaccine at 28-day intervals. After each dose, adverse events were prospectively evaluated, and blood samples were collected. The correlation between humoral immune response and reactogenicity after vaccination was determined. In 177 participants (19–55 years), the geometric mean titers of anti-S IgG antibody were 178.07 and 4409.61 U/mL, while those of 50% neutralizing titers were 479.95 and 2851.67 U/mL four weeks after the first and second vaccine doses, respectively. Anti-S IgG antibody titers were not associated with local reactogenicity but were higher in participants who experienced systemic adverse events (headache and muscle pain). Antipyretic use was an independent predictive factor of a robust anti-SARS-CoV-2 antibody response after receiving both vaccine doses. Systemic reactogenicity after the first dose influenced antibody response after the second dose. In conclusion, mRNA-1273 induced a robust antibody response in healthy young adults. Antipyretic use did not decrease the anti-SARS-CoV-2 antibody response after mRNA-1273 vaccination.

Enterohemorrhagic Escherichia coli (EHEC) causes hemorrhagic colitis and hemolytic uremic syndrome. EHEC infection begins with bacterial adherence to the host intestine via lectin-like adhesins that bind to the intestinal wall. However, EHEC-related lectin–glycan interactions (LGIs) remain unknown. Here, we conducted a genome-wide investigation of putative adhesins to construct an LGI network. We performed microarray-based transcriptomic and proteomic analyses with E. coli EDL933. Using PSORTb-based analysis, potential outer-membrane-embedded adhesins were predicted from the annotated genes of 318 strains. Predicted proteins were classified using TMHMM v2.0, SignalP v5.0, and LipoP v1.0. Functional and protein–protein interaction analyses were performed using InterProScan and String databases, respectively. Structural information of lectin candidate proteins was predicted using Iterative Threading ASSEmbly Refinement (I-TASSER) and Spatial Epitope Prediction of Protein Antigens (SEPPA) tools based on 3D structure and B-cell epitopes. Pathway analysis returned 42,227 Gene Ontology terms; we then selected 2585 lectin candidate proteins by multi-omics analysis and performed homology modeling and B-cell epitope analysis. We predicted a total of 24,400 outer-membrane-embedded proteins from the genome of 318 strains and integrated multi-omics information into the genomic information of the proteins. Our integrated multi-omics data will provide a useful resource for the construction of LGI networks of E. coli.

Background: Tick-borne lymphadenopathy (TIBOLA) is an infectious disease, mainly caused by species from the spotted fever group rickettsiae and is characterized by enlarged lymph nodes following a tick bite. Among cases of TIBOLA, a case of scalp eschar and neck lymphadenopathy after tick bite (SENLAT) is diagnosed when an eschar is present on the scalp, accompanied by peripheral lymphadenopathy (LAP). Only a few cases of SENLAT caused by Bartonella henselae have been reported. Case presentation: A 58-year-old male sought medical advice while suffering from high fever and diarrhea. Three weeks before the visit, he had been hunting a water deer, and upon bringing the deer home discovered a tick on his scalp area. Symptoms occurred one week after hunting, and a lump was palpated on the right neck area 6 days after the onset of symptoms. Physical examination upon presentation confirmed an eschar-like lesion on the right scalp area, and cervical palpation revealed that the lymph nodes on the right side were non-painful and enlarged at 2.5 × 1.5 cm. Fine needle aspiration of the enlarged lymph nodes was performed, and results of nested PCR for the Bartonella internal transcribed spacer (ITS) confirmed B. henselae as the causative agent. Conclusion: With an isolated case of SENLAT and a confirmation of B. henselae in Korea, it is pertinent to raise awareness to physicians in other Asian countries that B. henselae could be a causative agent for SENLAT.

Owing to the continuous increase in the number of new human immunodeficiency virus (HIV) infection in Korea, public health centers (PHCs) have performed anonymous tests since 1989. No study has examined the patterns of anonymous HIV testing performed at PHCs and the characteristics of HIV infection detected in those tests. We aimed to assess the influence of anonymous HIV testing on Korea’s national HIV surveillance. HIV screening test data from 253 PHCs over a 16-year period were classified into 13 groups based on reason for testing. For anonymous HIV test takers (Anonymous), the HIV positivity per 10,000 tests was calculated, as repetitions could not be distinguished. Those with suspected HIV infection voluntarily underwent HIV testing and revealed their identity (Suspected). HIV prevalence was calculated as the number of HIV-positive persons per 10,000 test takers. Analyses were performed using chi-square and Cochran-Armitage trend test with SAS 9.4. Approximately 400,000 HIV screening tests were performed at PHCs annually, which remained unchanged in the past 10 years. The proportion of anonymous testing increased from < 3.0% before 2014 to 4.8% in 2014 and 6.1% in 2015. While the number of HIV cases increased, the number of anonymous HIV-positive test results per 10,000 tests decreased from 68.8 in 2010 to 41.8 in 2015. The HIV prevalence among the suspected was approximately 20.0 per 10,000 test takers before 2014, which steeply increased to 71.6 in 2015. Those with suspected HIV were predominantly men, aged 20 years, foreigners, and metropolitan city dwellers in the last 6 years. The high prevalence of persons with suspected HIV resulted in a doubling of HIV prevalence at PHCs between 2014 and 2015. Anonymous and Suspected, which were driven by similar motives, impacted each other. Increase in HIV prevalence among the suspected led to a higher HIV prevalence among all test takers in PHCs and higher proportions of HIV infection nationwide, which could be attributed to the increase in the number of anonymous tests performed in PHCs. HIV positivity among the anonymous and HIV prevalence among the suspected are key indexes of the national HIV surveillance in Korea.

The complete genome sequences of three wild-type measles viruses (genotype D8) isolated from patients in South Korea were determined. These are the first reported complete genome sequences of measles viruses obtained from South Korea, and the availability of these sequences will improve our understanding of measles virus transmission and genetic diversity.

Recent years have seen a high incidence of mumps, which is generally diagnosed based on clinical features, especially parotitis, without laboratory confirmation in Korea. To better understand the epidemiology of mumps in Korean children, we investigated sporadic suspected mumps cases with parotitis. In total, 237 buccal swabs or throat swabs collected from children with parotitis who had been clinically diagnosed with mumps were tested using real‐time PCR for the detection of six viruses (Epstein‐Barr virus, Human herpesvirus 6, Mumps virus, Human parainfluenza virus‐1, ‐2, ‐3, Human adenovirus, Human bocavirus). Among 237 parotitis cases, 87 (36.7%) were positive for at least one virus; a single infection was observed in 73 (83.9%) cases, and co‐infections were detected in 14 (16.1%) cases. Epstein‐Barr virus was most frequent (20.7%), followed by human herpesvirus 6 (8.0%), mumps virus (5.5%), human parainfluenza virus‐3 (4.6%), human adenovirus (4.2%), and human bocavirus (0.4%). These data suggested that the sporadic suspected mumps in the children might be related to other respiratory viruses rather than to the mumps virus. Our findings also indicate the limitation of clinical diagnosis without laboratory confirmation for mumps and thus highlight the importance of laboratory testing in suspected mumps cases.

The complete genome sequence of the wild-type genotype 2B rubella virus RVi/Busan.KOR/10.15[2B], isolated from a patient in South Korea, was determined. The availability of this sequence will help in understanding the circulation of endemic rubella viruses, as well as their genetic diversity.

In 2015, the largest outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) infection outside the Middle East occurred in South Korea. We summarized the epidemiological, clinical, and laboratory findings of the first Korean case of MERS-CoV and analyzed whole-genome sequences of MERS-CoV derived from the patient. A 68-year-old man developed fever and myalgia 7 days after returning to Korea, following a 10-day trip to the Middle East. Before diagnosis, he visited 4 hospitals, potentially resulting in secondary transmission to 28 patients. On admission to the National Medical Center (day 9, post-onset of clinical illness), he presented with drowsiness, hypoxia, and multiple patchy infiltrations on the chest radiograph. He was intubated (day 12) because of progressive acute respiratory distress syndrome (ARDS) and INF-α2a and ribavirin treatment was commenced. The treatment course was prolonged by superimposed ventilator associated pneumonia. MERS-CoV PCR results converted to negative from day 47 and the patient was discharged (day 137), following rehabilitation therapy. The complete genome sequence obtained from a sputum sample (taken on day 11) showed the highest sequence similarity (99.59%) with the virus from an outbreak in Riyadh, Saudi Arabia, in February 2015. The first case of MERS-CoV infection had high transmissibility and was associated with a severe clinical course. The patient made a successful recovery after early treatment with antiviral agents and adequate supportive care. This first case in South Korea became a super-spreader because of improper infection control measures, rather than variations of the virus.