Rotaviruses are the single most important causes of severe acute diarrhoea in children worldwide. Despite success in developing
vaccines, there is still a lack of knowledge about many components of the immune response, particularly those to non-structural
proteins. This study established radioimmunoprecipitation (RIP) assays using labeled G1P[8], G2P[4], and G4P[6] human rotaviruses to examine the spectrum and duration of rotavirus
antibodies in sera collected sequentially for 18-36 months from 27 children after hospitalization for primary rotavirus
gastroenteritis. Five children experienced rotavirus
re-infections. Primary responses detected to non-structural
protein NSP2 declined to baseline after 100-150 days. Responses were heterotypic between NSP2 of G1P[8] and G4P[8] rotaviruses.
Re-infections after 465-786 days boosted antibody levels to NSP2of both serotypes, together with the appearance of anti-NSP2 to G2P[4], even though there was no evidence of
infection with this serotype. We developed an
enzyme-immunoassay to measure sequential levels of anti-NSP2
IgG and
IgA, using recombinant (heterotypic) NSP2 derived from SA11 (G3P[2]). Anti-NSP2
IgG and
IgA were detected in sera from 23/23 (100%) and 18/24 (75%) of children after primary
infection, declined to baseline after 100-150 days, were boosted after rotavirus
re-infections, and again declined to baseline 150 days later. Anti-NSP2
IgA was also detected after primary
infection, in duodenal juice from 14/16 (87%), and faecal extract from 11/19 (57%) of children. Sequential estimation of anti-NSP2 EIA levels in sera could be a sensitive index of
rotavirus infection and
re-infection. The potential of anti-NSP2 to limit viral replication after
re-infection deserves further study.