Detection of GII-4/2006b variant and recombinant noroviruses in children with acute gastroenteritis, South Korea.

Norovirus (NoV), a single-stranded, positive RNA virus, is an important etiologic agent of acute gastroenteritis in children worldwide. In this study, a total of 434 fecal samples collected from 434 children with acute gastroenteritis in Seoul, between September 2007 and July 2008 were tested to determine the molecular epidemiology of NoVs and characterize recombinant strains by using RT-PCR followed by sequencing. Of the 434 specimens, NoV, rotavirus, and adenovirus were detected in 155 (35.8%), 72 (16.6%), and 19 specimens (4.3%), respectively. NoV GI was detected in 7 specimens (1.6%) and GII in 148 (34.1%) specimens. Phylogenetic analysis of capsid sequences in the GII-positive specimens revealed the presence of the following strains: GII-4, 111 (75.0%); GII-3, 35 cases (23.6%); GII-6b, 1 case; and GII-16, 1 case. Most of the GII-4 strains were grouped with the GII-4/2006b variant with 98-100% nucleotide identity. Eleven strains were identified as recombinant (GII-4/GII-3 in 10 cases and GII-b polymerase/GII-16 capsid in 1 case) by sequencing based on the RdRP and capsid genes. The putative recombination point in the recombinant strains was the ORF-1/ORF2 overlap, located at nucleotide 5,046 with reference to Lordsdale. In conclusion, GII-4/2006b variants were detected predominantly and a new recombinant strain (GII-4/GII-3) was found in the Korean children with gastroenteritis. Continuous monitoring of the genetic diversity of NoVs is important to determine the trend of the predominant genotype and new recombinant strain.