Inseok Lim

Genetic variation of prevalent G1P[8] human rotaviruses in South Korea

The human rotavirus G1P[8] strain is one of the most common rotaviruses worldwide, including Korea. Six Korean G1P[8] human rotaviruses, isolated using cell culture techniques, were characterized on the basis of sequence differences in VP7, VP4, VP6, and NSP4 genes to elucidate the evolutionary relationships in the community. All strains had a long RNA electropherotype, supported by VP6 gene analysis, clearly associated with subgroup II specificity. The phylogenetic analysis of VP7 gene sequences showed that they all clustered into lineage I, as reported for G1 strains in Japan, China, Vietnam, and Thailand. In addition, phylogenetic analysis of the VP4 gene showed that they belong to two distinct lineages, P[8]‐II and P[8]‐III. With respect to the NSP4 gene, all strains belonged to genotype B. An understanding of the ecology and molecular evolution of rotaviruses circulating in the country is very important for the development of vaccines and vaccination strategies. This study provides new information concerning the genetic variability of the rotavirus strain G1P[8] occurring most commonly as a vaccine candidate. J. Med. Virol. 82: 886–896, 2010.

Genetic variation of G4P[6] rotaviruses: Evidence for novel strains circulating between the hospital and community

One hundred forty‐six fecal specimens collected between 2007 and 2008 from infants with acute gastroenteritis were screened for rotavirus by ELISA with VP6‐specific antibody. One hundred twenty‐three of the samples (84.2%) were confirmed to be positive for group A rotavirus (community‐acquired, n = 90 [73.2%] and nosocomial, n = 33 [26.8%]), and were typed subsequently using RT‐PCR and sequence analysis methods. Determination of G‐ and P‐type combinations showed that G4P[6] (78.9%) was the most common strain, followed by G3P[8] (7.3%), G1P[8] (6.5%), G2P[4] (0.8%), G2P[6] (0.8%), G1P[6] (0.8%), and G9P[8] (0.8%) strains. Of the 97 G4P[6] strains, 62 (63.8%) were responsible for community‐acquired cases and 35 (36.1%) were hospital‐acquired cases. Phylogenetic analysis of the VP7 gene from the G4P[6] strains revealed that both the community‐acquired and nosocomial strains were segregated to the human rotaviruses circulating world‐wide, including the prototype vaccinal strain, ST3, which constituted a novel sublineage in lineage 1. Owing to the recent emergence of G4P[6] rotaviruses within the hospital, as well as in the community, the findings from this study are important since they provide new information concerning the community and nosocomial spread of rotaviruses. J. Med. Virol. 82:700–706, 2010.

The indoor level of house dust mite allergen is associated with severity of atopic dermatitis in children.

We attempted to investigate the correlation between the severity of atopic dermatitis (AD) in children and the indoor level of house dust mite (HDM) allergens. Ninety-five patients (31.1 ± 19.5 months of age) with AD were enrolled in this study, and serum specific IgE against Dermatophagoides pteronyssinus and D. farinae was measured. The severity of AD was assessed using the visual analogue scale on the same day of house dust collection. Living rooms and mattresses where the child usually slept were vacuumed for 2 minutes and concentrations of Der f 1 were measured by enzyme-linked immunosorbent assay. The skin symptoms were more severe in patients with Der f 1 concentrations in living room > 2 µg/g dust than ≤ 2 µg/g dust (P = 0.018). This difference was noted in AD patients without sensitization to HDM (P = 0.004), but not in patients with sensitization. There was no difference in symptom severity according to Der f 1 concentrations in mattresses (P = 0.062). The severity of skin symptoms is associated with indoor concentrations of HDM in children with AD, and it is likely to act as nonspecific irritants as well as allergens in AD skin lesions.

Molecular characterization of rotavirus diarrhea among children in South Korea: detection of an unusual G11 strain

Among 312 rotavirus-positive samples collected from eight hospitals across South Korea during 2008 and 2009, the most prevalent circulating G genotype was G1 (35.9%), followed by G3 (24.7%), G2 (17.0%), G4 (7.7%), and G9 (2.6%). Notably, one unusual G11 lineage III strain—the first hypoendemic infection case in the world—was found. Of the P genotypes, P[8] (43.9%) was the most common, followed by P[6] (29.5%), P[4] (9.3%) and P[9] (0.6%). Determining G- and P-type combinations showed that G1P[8] was the most prevalent (20.5%), followed by G2P[6] (12.8%) and G3P[8] (12.8%). These findings provide new information concerning the current prevalence and spread of the rare G11 rotavirus.

Emergence of Norovirus GII.17 Variants among Children with Acute Gastroenteritis in South Korea.

Of 1,050 fecal specimens collected from January 2013 to August 2015 from children with acute gastroenteritis, 149 (14.2%) were found to be positive for norovirus. Norovirus GII was the most predominant genogroup (98.65%; 147 of 149). The genotypes detected in this study were GI (2; 1.3%), GII.Pe-GII.4 (109; 73.1%), GII.P17-GII.17 (16; 10.7%), GII.P12-GII.3 (8; 5.4%), GII.P12-GII.12 (8; 5.4%), GII.P4-GII.4 (5; 3.4%), and the recombinant GII.Pe-GII.17 (1; 0.7%). Of these, the novel GII.17 strain was the second most predominant, and the number of affected children appeared to continuously increase over time (2013 [2; 4.4%], 2014 [4; 9.3%], and 2015 [10; 16.4%]). Phylogenetic analysis of the full genome and ORF1, ORF2, and ORF3 nucleotide sequences showed that GII.17 was grouped in cluster III with other strains isolated from 2013 to 2015 and had a different evolutionary history from strains collected in 1978 to 2002 and 2005 to 2009 formed clusters I and II. However, the phylogenetic trees also showed that cluster III was divided into subclusters IIIa (CAU-55 and CAU-85) and IIIb (Kawasaki 2014) (CAU-193, CAU-265, CAU-267, CAU-283, and CAU-289). Comparative analysis of the VP1 capsid protein using 15 complete amino acid sequences from noroviruses isolated from 1978 to 2015 showed 99 amino acid changes. These results could be helpful for epidemiological studies to understand circulating norovirus genotypes in population.

Genetic characterization of norovirus GII.4 2006b variants from Jeju island, South Korea.

Ninety‐seven fecal specimens collected from children with acute gastroenteritis between 2007 and 2008 that were found to be negative for group A rotavirus in prescreening by ELISA with VP6‐specific antibody were re‐screened for viruses by reverse transcription (RT)‐PCR. Forty (41.2%) samples were found to be positive for virus by RT‐PCR; of these, norovirus (32.5%, n = 13) and rotavirus (32.5%, n = 13) were the most common, followed by astrovirus (5.0%, n = 2) and enterovirus (2.5%, n = 1). Co‐infection was found in 11 (27.5%) samples. Phylogenetic analyses of the ORF2 nucleotide sequences of 21 norovirus strains showed that 19 (90.5%) belonged to the genogroup GII genotype 4 and two (9.5%) belonged to genogroup GI genotype 4. The GII.4 strains demonstrated high sequence homology and were closely related to new 2006b variants observed in Europe, China, Hong Kong, and Japan in 2006. This study provides new information concerning the recent global epidemic of 2006b strains. J. Med. Virol. 82:1065–1070, 2010.

Molecular characterization of serotype G9 rotaviruses circulating in South Korea between 2005 and 2010.

A total of 18 rotavirus G9 strains in South Korea were collected during five rotavirus seasons between 2005 and 2010. The relationship between these strains was examined by analyzing the genetic variation of two major structural genes, VP7 and VP4. All the rotavirus isolates were of the G9P[8] genotype. The VP7 phylogenetic analysis demonstrated that all of the G9 rotaviruses circulating in South Korea belonged to lineage IIId and were within three single clusters. The amino acid comparison of the antigenic regions of the VP7 gene suggests possible common progenitors of these strains. Phylogenetic analysis of P[8] VP4 genotypes indicated three lineages, P[8]‐2, P[8]‐3, and P[8]‐4, with P[8]‐3 being the most common. The results of this study provide information on the genetic relatedness of rotavirus G9 strains circulating in South Korea over recent years and can be utilized for the development of effective vaccines and the identification of reference strains for future efficacy studies. J. Med. Virol. 85:171–178, 2012.

Full genomic characterization of a group C rotavirus isolated from a child in south Korea

During an epidemiological survey of human rotavirus infection in Seoul, Korea, from 2010 to 2011, one isolate of group C rotavirus (GCRV), named CAU10‐312, was detected in a 5‐year‐old child admitted to the hospital with acute gastroenteritis, and its complete genomic sequence was determined. The 11 gene segments of the strain possessed G4‐P[2]‐I2‐R2‐C2‐M2‐A2‐N2‐T2‐E2‐H2 genotypes. The genotype of strain CAU10‐312 appears to be closely related to strains from Bangladesh (DhakaC13 and BS347), India (v508), and England (Bristol), but distinct from Far East Asian strains, Chinese (Wu82 and YNR001) and Japanese (OH567 and BK0830). These findings may clarify the relationship of the genetics, evolutionary biology, and epidemiology of GCRVs and suggest that two very distinct genotype strains are in circulation in the world. J. Med. Virol. 85:1478–1484, 2013.

Distribution of rotavirus G and P genotypes approximately two years following the introduction of rotavirus vaccines in South Korea

Genotyping of human rotaviruses was performed on 299 (40.1%) rotavirus‐positive samples obtained from 745 children with acute diarrhea in three provinces in South Korea between March 2008 and February 2010, approximately 2 years following the introduction of the RotaTeq (September 2007) and Rotarix (July 2008). The most prevalent G genotypes were G1 (51.5%), followed by G3 (24.0%), G4 (15.4%), G9 (6.4%), and G2 (4.7%). The predominant types of P genotypes were P[8] (72.6%), followed by P[6] (19.1%) and P[4] (6.0%). The phylogenetic analyses of the VP7 genes of G9 strains revealed they were highly identical and belonged in lineage III. This study highlights the consistency of the predominant G1 genotype and slightly higher predominance of the identical G9 strains over the G2 genotype. J. Med. Virol. 85:1307–1312, 2013.

Whole-Genome Analysis of a Rare Human Korean G3P[9] Rotavirus Strain Suggests a Complex Evolutionary Origin Potentially Involving Reassortment Events between Feline and Bovine Rotaviruses

A rare human rotavirus, G3P[9] strain RVA/Human-tc/KOR/CAU12-2-51/2013/G3P[9], was isolated from the stool of a 9-year-old female hospitalized with acute watery diarrhea in August 2012 in South Korea using a cell culture system, and its genome was analyzed. The complete genomic constellation of the CAU12-2-51 strain revealed a novel genotype constellation for human rotavirus, G3-P[9]-I2-R2-C2-M2-A3-N2-T3-E3-H3. Phylogenetic analysis revealed that the CAU12-2-51 strain originated from feline- and bovine-like reassortment strains. The genes encoding VP4, VP7, NSP1, NSP3, NSP4, and NSP5 were related to human/feline-like and feline rotavirus strains, whereas the remaining five genes encoding VP1, VP2, VP3, VP6, and NSP2 were related to the human/bovine-like and bovine rotavirus strains. This novel strain was identified for the first time, providing evidence of feline/bovine-to-human transmission of rotavirus. The data presented herein provide information regarding rotavirus diversity and evolution.