The biological characteristics of a West Nile virus strain

Objective To investigate the biological characteristics of an imported West Nile virus (WNV) strain, covering morphology, pathogenicity, cell line sensitivity. Methods Cytopathogenic effect (CPE) caused by WNV was observed in Vero-E6 and C6/36 cells, and the negative stain and tissue slice samples for electron microscopy were prepared. Suckling mice were inoculated intracerebrally to observe the pathogenicity of WNV. BALB/c mice were immunized with inactivated WNV, and their serum antibodies against WNV were measured by indirect immunofluorescence assay (IFA). A RT-PCR method was used to detect viral RNA, and then the homology analysis of nucleoside sequence was performed with BLAST program. Results WNV-caused CPEs were characterized by cell shrinking and fusion in Vero-E6 and C6/36 cells respectively. The morphologic observation showed that the virion was spheral particle (approximately 30-50 nm in diameter) with envelope. Suckling mice inoculated with WNV were all killed. Serum antibodies against the virus were detectable in BALB/c mice immunized with inactivated WNV. The target DNA fragments which were only matched with WNV could be amplified from both the virus cultures and brain tissues of infected suckling mice. Conclusion The results can be used for further WNV-related studies.