Preparation of the recombinant VCA and NA proteins of Epstein-Barr virus and application of serological diagnosis of nasopharyngeal carcinoma

Abstract

Objective To study the recombinant viral eapsid antigen (VCA)- BFRF3 and NA-BKRF1 proteins of Epstein-barr (EB) virus for serological diagnosis of nasopharyngeal eareinoma (NPC).Methods EB virus DNA was used as the templates in a polymerase chain reaction (PCR). VCA-BFRF3 and NA1-BKRF1 were amplified and inserted into E.eoli expression veetor pET-51b. The reeombinant plasmids were transformed into JM 109 E.coli, and induced expression of IPTG reeombinant proteins. After analyzed by SDS- PAGE and immunoblot, expressed products were purified by immobilized metal ion affinity chromatography. The preparation of BFRF3, BKRF1 and the eombination of BFRF3/BKRF1 were served respeetively as solid phase antigens of ELISA to detect EBV-IgA antibody in NPC patients and healthy people. Results The BFRF3 and BKRF1 proteins had been expressed in E.colis. The relative molecular weight of products were approximately 20 000 and 29 000 respectively. The reeombinant proteins showed good immunoreaetivity. NPC diagnostic sensitivity of BKRF1 (71.20% , 178/250)was signifieancent higher than that of BFRF3 (64.80% , 162/250) (P<0.01) , but there was no difference in diagnostic specificity between them. Combined with BKRF1 and BKRF3, higher diagnostic sensitivity (84.80%, 212/250) and lower diagnostic specificity (82.00%, 328/400)eould be obtained. Conclusion NPC diagnostic sensitivity of BKRF1 was higher than that of BFRF3.Combined with BKRF1 and BKRF3, higher diagnostie sensitivity and lower diagnostic speeifieity could be obtained. Key words: Nasopharyngeal neoplasms; Gene BFRF3; Gene BKRF1 ; Epstein-barr virus; Viralcapsid antigen; Recombinant protein; Target gene