DETECTION OF HUMAN-ANTIBODIES TO CRIMEAN-CONGO HEMORRHAGIC-FEVER VIRUS USING EXPRESSED VIRAL NUCLEOCAPSID PROTEIN

Diagnosis of Crimean-Congo haemorrhagic fever (CCHF) virus infections is hampered by the problems of handling this human pathogen, which req uires the highest levels of biological containment. Recombinant antige ns were examined for their potential as nonhazardous diagnostic reagen ts. The nucleocapsid (N) gene of the Greek AP92 isolate of CCHF virus was sequenced from cloned PCR products and the open reading frame was identified by homology to the N protein of a Chinese isolate of CCHF v irus. The N protein was expressed to high levels in a baculovirus expr ession system. Three N protein-derived peptides were expressed in Esch erichia coli as fusions with glutathione S-transferase and the antigen icities of these proteins and the baculovirus-expressed protein were t ested by ELISA. When tested with laboratory animal sera representing a ll seven serogroups of nairoviruses, the only reactive sera were those raised to CCHF virus (Greek, Nigerian and Chinese isolates) and, more weakly, Hazara virus. When tested with a panel of known positive and negative human sera, the baculovirus-expressed N protein, and the pept ide derived from the central region of the N protein, proved to be the best for identifying CCHF virus-specific IgG.