Related Experiment Videos
Attenuation of virulence of flaviviruses following passage in HeLa cells
L M Dunster1, C A Gibson, J R Stephenson
1Department of Microbiology, University of Surrey, Guildford, U.K.
Abstract:
The ability of passage in HeLa cells to attenuate flaviviruses was investigated for three different strains of the mosquito-borne West Nile (WN) virus and two tick-borne viruses, louping-ill and Langat. One strain of WN virus, Sarawak, was attenuated 4000-fold for adult mice by intraperitoneal or intranasal challenge after six HeLa passages. The HeLa-passaged virus was also found to be antigenically different and temperature-sensitive in its growth characteristics compared with the parent. After six HeLa cell passages the Egypt 101 and Smithburn strains of WN virus lost their ability to infect monkey kidney cells and no longer killed adult mice, although inoculated animals became sick for several days. In contrast, two tick-borne flaviviruses remained as virulent for mice after six HeLa passages as the parent non-HeLa-passaged virus. Neither of the tick-borne viruses exhibited characteristics associated with temperature sensitivity. The results, therefore, indicate that the mosquito-borne, but not tick-borne, flaviviruses can be attenuated by very few passages in HeLa cells. This observation may provide a model system with which to analyse the molecular basis of attenuation and/or virulence of mosquito-borne flaviviruses.
Insights
Passaging mosquito-borne West Nile virus in HeLa cells significantly attenuates its virulence in mice. This HeLa cell passage method offers a potential model for studying flavivirus attenuation and virulence factors.
Area of Science:
- Virology
- Cell Biology
- Infectious Diseases
Background:
- Flaviviruses, transmitted by mosquitoes and ticks, pose significant public health challenges.
- Understanding viral attenuation is crucial for developing effective vaccines and therapeutics.
- HeLa cells are a widely used human cell line for viral research.
Purpose of the Study:
- To investigate the potential of HeLa cell passaging to attenuate flaviviruses.
- To compare the attenuation of mosquito-borne and tick-borne flaviviruses in HeLa cells.
- To explore the characteristics of attenuated flaviviruses, including antigenic and temperature-sensitive properties.
Main Methods:
- Three strains of West Nile virus (mosquito-borne) and two tick-borne flaviviruses (louping-ill and Langat) were subjected to six passages in HeLa cells.
- Attenuated viruses were tested for virulence in adult mice via intraperitoneal or intranasal challenge.
- Antigenic differences and temperature sensitivity of HeLa-passaged viruses were assessed compared to parent strains.
Main Results:
- One West Nile virus strain (Sarawak) showed a 4000-fold attenuation in mice after HeLa passaging and exhibited antigenic changes and temperature sensitivity.
- Two other West Nile virus strains (Egypt 101 and Smithburn) lost infectivity for monkey kidney cells and were no longer lethal to mice post-HeLa passaging.
- Tick-borne flaviviruses remained virulent after HeLa passaging and did not display temperature sensitivity.
Conclusions:
- HeLa cell passaging effectively attenuates mosquito-borne flaviviruses, but not tick-borne flaviviruses.
- The observed attenuation is associated with antigenic drift and temperature sensitivity in mosquito-borne flaviviruses.
- This HeLa cell passage system may serve as a valuable model for dissecting the molecular mechanisms of flavivirus attenuation and virulence.