A recombinant baculovirus containing the complete open-reading frame (ORF)-2 region of the hepatitis E virus (HEV) genome was constructed. The major protein synthesized in insect cells infected with recombinant virus was about the size expected for the complete ORF-2 product. This protein reacted in a Western blot assay with plasma from an HEV-infected chimpanzee. Lysates of the recombinant virus-infected insect cells were used in ELISA to monitor seroconversion of eight primate species (chimpanzees, four species of Old World monkeys, and three species of New World monkeys) inoculated with HEV. Homologous detector anti-immunoglobulin was more sensitive than heterologous anti-immunoglobulin for detecting anti-HEV by ELISA. All primate species except tamarins seroconverted after inoculation with HEV, although anti-HEV titers of Old World monkey species were generally higher than those of New World monkey species. The ELISA with complete ORF-2 antigen appeared to be a sensitive and practical method for detecting anti-HEV.