DETECTION OF NORWALK-VIRUS AND OTHER GENOGROUP-1 HUMAN CALICIVIRUSES BY A MONOCLONAL-ANTIBODY, RECOMBINANT-ANTIGEN-BASED IMMUNOGLOBULIN-M CAPTURE ENZYME-IMMUNOASSAY

Sera obtained from two groups of adult volunteers infected with Norwal k virus (NV) and two groups of patients involved in two natural outbre aks were tested for NV-reactive immunoglobulin M (IgM) by use of a mon oclonal antibody, recombinant-antigen-based IgM capture enzyme immunoa ssay (EIA). No NV-reactive IgM was detected in the preinoculation sera of 15 volunteers, and 14 of 15 showed NV-reactive antibodies postinfe ction with NV. All of the volunteers showed IgG seroconversion to NV. In the outbreak studies, all 9 persons in one outbreak and 19 of 24 in another outbreak had NV-reactive IgM., In the first outbreak, only th ree of nine seroconverted to NV, which was likely due to late collecti on of acute-phase sera, In the second outbreak, 21 of 24 showed IgG se roconversion to NV, Sequencing of viruses isolated from five stool sam ples selected from those in the second outbreak showed that they were human calicivirus (HuCV) genogroup 1 viruses related, but not identica l, to NV. In the volunteer studies, NV-reactive IgM was first detected 8 days postinoculation, The time of development of NV-reactive IBM an tibodies in natural outbreaks was estimated to be similar to that foun d in the volunteer studies, Sera from three Hawaii virus-infected volu nteers, four Snow Mountain virus patients, and 80 healthy individuals were negative for NV-reactive IgM, indicating test specificity for HuC V genogroup I infections, This capture IgM EIA is suitable for diagnos is of NV and other HuCV genogroup I infections and is especially usefu l when sera and fecal samples have not been collected early in the cou rse of an outbreak.