Nusra SittidilokratnaNatthida PhetchampaiVichai BoonsaengPeter J. WalkerThailand National Center for Genetic Engineering and BiotechnologyMahidol UniversityCSIRO Livestock Industries2018-08-202018-08-202006-03-01Virus Research. Vol.116, No.1-2 (2006), 21-29016817022-s2.0-32344436343https://repository.li.mahidol.ac.th/handle/20.500.14594/23076Yellow head virus (YHV) is an invertebrate nidovirus that is highly pathogenic for marine shrimp. Nucleotide sequence analysis indicated that the YHV ORF2 gene encodes a basic protein (pI = 9.9) of 146 amino acids with a predicted molecular weight of 16,325.5 Da. The deduced amino acid sequence indicated a predominance of basic (15.1%), acidic (9.6%) and hydrophilic polar (34.3%) residues and a high proportion proline and glycine residues (16.4%). The ORF2 gene was cloned and expressed in Escherichia coli as a Mr= 21 kDa His6-protein that reacted with YHV nucleoprotein (p20) monoclonal antibody. Segments representing the four linear quadrants of the nucleoprotein were also expressed in E. coli as GST-fusion proteins. Immunoblot analysis using YHV polyclonal rabbit antiserum indicated the presence of linear epitopes in all except the V37-Q74quadrant. Immunoblot analysis of the GST-fusion proteins and C-terminally truncated segments of the nucleoprotein allowed mapping of YHV monoclonal antibodies Y19, Y20 and YII4 to linear epitopes in the acidic domain between amino acids I116and E137. The full-length nucleoprotein was expressed at high level in E. coli and was easily purified in quantity from the soluble cell fraction by Ni+-NTA affinity chromatography. © 2005 Elsevier B.V. All rights reserved.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyImmunology and MicrobiologyMedicineArticleSCOPUS10.1016/j.virusres.2005.08.009