SERUM ANTIBODY-RESPONSE TO RECOMBINANT MAJOR INNER CAPSID PROTEIN FOLLOWING HUMAN INFECTION WITH GROUP-B ROTAVIRUS

2Recombinant major inner capsid protein (VP6) of the IDIR strain of gr oup B rotavirus (GBR) was incorporated in a solid-phase immunoassay to access antibody response to infection in humans. Expression of VP6 in insect cells permitted design of a highly sensitive assay that avoide d the contaminants present in GBR antigens obtained from fecal specime ns. Among patients infected with the ADRV strain of GBR in China, incr eased reactivity with recombinant VP6 was observed in convalescent-pha se sera in comparison with sera obtained shortly after infection (P = 0.0084). Anti-VP6 antibodies were detectable as soon as 7 days after o nset of gastrointestinal symptoms, and serum reactivity persisted in s pecimens drawn more than 1 year after infection. Solid-phase immunoass ay with recombinant VP6 was next employed in order to assess anti-GBR antibody in 513 serum specimens obtained from 423 Maryland residents ( ages, 7 months to 96 years; median age, 42 years). Four individuals (< 1%) exhibited serum antibodies directed against the recombinant VP6 (a ges, 54 to 95 years; mean age, 77 years). Examination of 129 additiona l serum specimens including some from other geographic regions of the United States failed to reveal the presence of anti-GBR antibody. Anti -GBR antibody was also wt detected in any of 131 serum specimens from 60 staff and residents of a nursing home in Switzerland. White infecti on of humans with GBR has been uncommon in these locations outside of China, the detection of serum antibodies in older individuals in the U nited States either indicated an unknown 21, age-related risk factor o r may have indicated infection in the more distant past. The availabil ity of these reagents should allow surveys for GBR infection among add itional populations that have not previously been investigated.