Abstract
Noroviruses (NoVs) are the second most common cause of viral gastroenteritis after rotavirus in children. NoV genotype GII‐4 has emerged as the major type not only in outbreaks of NoV gastroenteritis but also endemic gastroenteritis among infants and young children worldwide. Using baculovirus‐insect cell system virus‐like particles (VLPs) of NoV genotype GII‐4 and an uncommon genotype GII‐12 were produced. These VLPs were used in enzyme‐linked immunosorbent assays (ELISA) for detection of NoV‐specific immunoglobulin G (IgG) and IgA antibodies in 492 serum specimens from Finnish children 0–14 years of age collected between 2006 and 2008. NoV IgG antibody prevalence was 47.3% in the age group 7–23 months and increased up to 91.2% after the age of 5 years. Avidity of NoV IgG antibodies was low in the primary infections while high avidity antibodies were detected in the recurrent infections of the older children. In GII‐4 infections, the homologous antibody response to GII‐4 VLPs was stronger than to GII‐12 VLPs but cross‐reactivity between GII‐4 and GII‐12 was observed. Binding of GII‐4 VLPs to a putative carbohydrate antigen receptor H‐type 3 could be blocked by sera from children not infected with NoV during a waterborne outbreak of acute gastroenteritis. Therefore, protection against NoV infection correlated with strong blocking activity. J. Med. Virol. 83:525–531, 2011. © 2011 Wiley‐Liss, Inc.