Introduction: Houston/90 (Hou/90) is a human calicivirus (HuCV) strain in one of three clades of Sapporo-like HuCVs that cause acute gastroenteritis in children. The viral capsid gene of Hou/90 has been cloned and sequenced (Arch Virol, 1997; 142:1813). Methods: Hou/90 capsid was expressed in a baculovirus expression system and its antigenicity was determined by immunoprecipitation and enzyme immune assays (EIAs) using serum specimens from three children infected with Hou/90. Electron microscopy was used to examine the morphology of viral capsid. Results: Virus-like particles (VLPs) self-formed in insect cells infected with the recombinant baculovirus containing the Hou/90 capsid gene. The VLPs were empty and contained a single capsid protein with a molecular weight of 60 KD. When used as antigen, the Hou/90 VLPs detected seroresponses of children infected with Hou/90 in an EIA and by immunoprecipitation. Hou/90 VLPs were not detected by EIAs specific for Norwalk, MX and prototype Sapporo/82 strains. Conclusion: Hou/90 VLPs are distinct antigenically from strains belonging to different HuCV genera and Sapporo-like clades. Availability of unlimited amounts of the recombinant baculovirus Hou/90 capsid will allow development of diagnostic assays for clinical and epidemiological studies of the strain.