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Strain analysis and epitope mapping of West Nile virus using monoclonal antibodies
R G Damle1, L R Yeolekar, B L Rao
1National Institute of Virology, Maharashtra, India.
Abstract:
Monoclonal antibodies (MAbs) against an Indian strain (804994) and an Egyptian strain (E 101) of West Nile virus (WNV) were prepared in mice. Nine MAbs against the 804994 strain and 5 MAbs against E 101 strain were obtained. All 14 MAbs reacted with the envelope (E) protein of WNV in an immunoblot assay. They were tested by an enzyme-linked immunosorbent assay (ELISA) for their cross-reactivity with WNV, Japanese encephalitis virus (JEV) and Dengue-2 virus (DEN-2), and for their reactivity in haemagglutination-inhibition (HAI) test. Based on these results MAbs were broadly grouped into three groups, namely WNV-specific HAI-positive, WNV-JEV cross-reactive HAI-positive, and WNV-JEV cross-reactive HAI-negative MAbs. The antigenic cross-reactivity between twelve WNV strains isolated from different geographical regions and their respective hosts was assessed using these MAbs in HAI and complement fixation (CF) tests. The strain analysis by CF distinguished Indian from South African strains. However, a similarity between some Indian and South African strains in HAI was observed. E 101 strain appeared to have antigenic similarity with Indian as well as South African strains. Overall it appears that antigenically similar strains of WNV are prevalent in India. A single heterogenous domain was apparent on the epitope map of WNV deduced by ELISA additivity test.
Insights
Researchers developed monoclonal antibodies (MAbs) to study West Nile virus (WNV) strains. Antigenic analysis revealed similarities among WNV strains prevalent in India, suggesting a common evolutionary origin.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- West Nile virus (WNV) is a significant public health concern.
- Understanding the antigenic diversity of WNV strains is crucial for developing effective diagnostics and vaccines.
- Monoclonal antibodies (MAbs) are valuable tools for characterizing viral antigens.
Purpose of the Study:
- To generate and characterize MAbs against Indian and Egyptian strains of WNV.
- To investigate the antigenic relatedness of different WNV strains using these MAbs.
- To map the epitope domains on the WNV envelope (E) protein.
Main Methods:
- Production of MAbs in mice against WNV strains 804994 (Indian) and E 101 (Egyptian).
- Immunoblot assay to confirm reactivity with WNV E protein.
- Enzyme-linked immunosorbent assay (ELISA) for cross-reactivity testing with WNV, Japanese encephalitis virus (JEV), and Dengue-2 virus (DEN-2).
- Haemagglutination-inhibition (HAI) and complement fixation (CF) tests for antigenic cross-reactivity analysis of multiple WNV strains.
- ELISA additivity test for epitope mapping.
Main Results:
- Fourteen MAbs were generated, all reactive with the WNV E protein.
- MAbs were categorized into WNV-specific, WNV-JEV cross-reactive HAI-positive, and WNV-JEV cross-reactive HAI-negative groups.
- Antigenic analysis using HAI and CF tests revealed distinct Indian and South African WNV strains, with some overlap observed.
- The Egyptian E 101 strain showed antigenic similarity to both Indian and South African strains.
- ELISA additivity tests indicated a single heterogeneous domain on the WNV epitope map.
Conclusions:
- Antigenically similar WNV strains appear to be prevalent in India.
- The study provides insights into the antigenic relationships between geographically diverse WNV strains.
- The generated MAbs are useful tools for WNV strain characterization and epitope mapping.