Cloning and Expression of Nucleocapsid Protein Gene of SARS Associated Coronavirus
Abstract: Abstract:Nucleocapsid gene of SARS·-associated coronavirus(SARS·-CoV)was obtained by reverse tran scription and polymerase chain reaction from a pateint sufered from severe acute respiratory syndrome(SARS)from Beijing,subsequently cloned into pUCm—T vector.The sequence of positive recombinants was determined by the method of dideoxy chain termination,which revealed that the nucleocapsid gene segment is 1 269 nucleotide in length with an open reading frame encoding a protein of 422 am ino acids.Nucleocapsid gene was subcloned into the prokaryotic vector pET28a.Th e recombinant plasmid pET28a—SN was transformed into host cell BL21(DE3).After inducing by IPTG~ about 50kD protein was expressed and the expression level was about 45% .W estern—blot an alysis demonstrated that the recombinant proteins reacted with SARS positive sera but not with norm al sera tested. SARS nucleocapsid protein expressed by the E.coli system ofer a safe source of specific antigen for diagnostic purposes.