Expression and characterization of Sapporo-like human calicivirus capsid proteins in baculovirus

Sapporo-like caliciviruses reveal typical calicivirus morphology and cause acute gastroenteritis. This study describes the expression in baculovirus o f capsid proteins of two Sapporo-like calicivirus strains (Hou/86 and Hou/9 0). Eight different constructs of the capsid genes were compared for produc tion of the proteins. Constructs containing short (9 or 19 nt) upstream seq uences failed to produce capsid proteins but extension of the upstream sequ ence to 73 nt resulted in production of capsid proteins. Expressed capsid p rotein with the MEG tri-peptide as the N-terminus self-formed virus-like pa rticles (VLPs). Expressed protein with an upstream AUG failed to form VLPs. Addition of His-tag to the N-terminus of capsid protein also blocked VLP f ormation. Of three Norwalk-Hou/90 chimeric capsid gene constructs, one resu lted in production of chimeric capsid and the protein did not form VLPs. Re combinant capsid proteins for each of Hou/86 and Hou/90 were further charac terized. The expressed capsid antigens of the two strains were antigenicall y distinct but shared a common epitope(s). Further study of these proteins should allow development of immunologic assays for diagnosis and should hel p to clarify the epidemiology of Sapporo-like caliciviruses in humans. (C) 1999 Elsevier Science B.V. All rights reserved.