Cho SR, et al. J Korean Med Sci. 2020 Jul;35(34):e281. https://doi.org/10.3346/jkms.2020.35.e281

Noroviruses are a leading cause of acute gastroenteritis worldwide, with a particularly high burden among children under five years of age. We analyzed nationwide surveillance data from EnterNet-Korea collected between 2019 and 2024—covering both the pre- and post-COVID-19 pandemic periods—to assess norovirus detection rates and genotype distribution. Noroviruses were detected by RT-qPCR, and dual genotyping of capsid (G) and polymerase (P) types was performed by sequencing the ORF1–2 junction region. Among the 67,159 specimens tested, 8.4% (n = 5652) were norovirus-positive, with the highest prevalence observed in children aged 0–5 years (19.9%). In this age group, genotyping was successful in 72.4% (2633/3635) of positive cases, identifying 30 distinct genotypes (GI: 9; GII: 21). The most common strains were GII.4[P31] (38.1%), GII.4[P16] (27.1%), and GII.2[P16] (10.4%), with substantial year-to-year variation. Notably, the emergence of GII.17[P17] in late 2024 indicates shifting genotype dynamics, underscoring the need for strengthened surveillance and reconsideration of vaccine strain selection. To our knowledge, this is the first nationwide dual-typing study in Korea encompassing the COVID-19 pandemic era. These findings provide essential baseline data for integration into global surveillance systems and inform future vaccine development and public health strategies.

Chae SJ, et al. Infect Chemother. 2020 Dec;52(4):616-620. https://doi.org/10.3947/ic.2020.52.4.616

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.

Japanese encephalitis virus (JEV) is a mosquito-borne zoonotic flavivirus causing severe neurological disease across Asia, and genotype V (GV) is now predominant in Korea. Despite frequent detection of GV in mosquitoes, human-derived complete genome data remain scarce. To elucidate the molecular and antigenic characteristics of human GV infections, cerebrospinal fluid samples from unvaccinated patients positive for JEV RNA during 2018–2023 were subjected to virus isolation in LLC-MK2 cells (rhesus monkey kidney-derived epithelial cell line). Three human GV isolates (K18P80, K23P84, K23P88) were successfully obtained and their complete open reading frames (~10.3 kb) sequenced. Phylogenetic analysis with representative JEV strains (GI–GV) revealed that these isolates form a distinct lineage, clustering into two domestic clades (Clade I and II), suggesting endemic circulation and local evolution in Korea. Sequence identities with GIII-based vaccine strains were low (79% nucleotide, 91.1% amino acid), with notable divergence in nonstructural regions. Three consistent E protein substitutions (Q52E, S156T, D292E) near antigenic epitopes indicate possible immune escape. Additional clade-defining substitutions in NS3 (L31F) and NS5 (K269R, M330I) were shared with mosquito isolates, supporting human–vector molecular continuity. These findings provide fundamental genomic evidence of human JEV GV in Korea and highlight the need for genotype-specific surveillance and next-generation vaccine evaluation.

Lee YJ, et al. J Korean Med Sci. 2027 Feb;42:e19. https://doi.org/10.3346/jkms.2027.42.e19