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Establishment and characterization of St Louis encephalitis virus persistent infections in Aedes and Culex mosquito
1Department of Biomedical and Environmental Health Sciences, School of Public Health, University of California, Berkeley 94720.
Abstract:
Persistent infections with St Louis encephalitis (SLE) virus were established in three mosquito cell lines (Aedes albopictus, A. dorsalis and Culex tarsalis) and were maintained for over 2 years. All three persistently infected cell cultures shared two features: (i) no overt cytopathic effect and (ii) a relatively high proportion of cells infected (41 to 85%). The Aedes persistently infected cultures were resistant to superinfection with the homologous virus but not heterologous viruses. Two significant differences were observed between the Aedes and C. tarsalis persistently infected cell cultures: (i) viral titres in the A. albopictus and A. dorsalis cell cultures decreased slowly over time (the decrease was particularly marked in the A. albopictus cell cultures), whereas titres in the C. tarsalis cell cultures remained relatively constant and (ii) the addition of anti-SLE virus antibody led to decreased virus production in the C. tarsalis cell cultures (one of two cultures was cured of infection), whereas antibody had no effect on the persistently infected Aedes cell cultures. These results suggest that there may be significant differences in the regulation of viral replication and the maintenance of flavivirus persistent infections in mosquito cell lines of different origins.
Insights
Persistent St Louis encephalitis (SLE) virus infections were established in mosquito cell lines. Differences in viral replication and antibody response suggest varied flavivirus persistence mechanisms in different mosquito cell origins.
Area of Science:
- Virology
- Infectious Diseases
- Cell Biology
Background:
- Persistent viral infections can evade host immune responses.
- Mosquito cell lines are crucial models for studying arboviruses like St Louis encephalitis (SLE) virus.
- Understanding flavivirus persistence in vector cells is key to controlling transmission.
Purpose of the Study:
- To establish and characterize persistent St Louis encephalitis (SLE) virus infections in three distinct mosquito cell lines.
- To investigate differences in viral replication, superinfection resistance, and antibody-mediated effects in these persistently infected cell cultures.
- To explore potential variations in flavivirus persistence mechanisms across different mosquito vector species.
Main Methods:
- Establishing persistent SLE virus infections in Aedes albopictus, Aedes dorsalis, and Culex tarsalis cell lines over two years.
- Monitoring for cytopathic effects and quantifying infected cell proportions.
- Assessing resistance to homologous and heterologous virus superinfection.
- Measuring viral titers over time and evaluating the impact of anti-SLE virus antibodies.
Main Results:
- All three cell lines exhibited persistent SLE virus infection without overt cytopathic effects, with 41-85% of cells infected.
- Aedes cell cultures showed resistance to homologous superinfection but not heterologous viruses.
- Viral titers declined over time in Aedes cultures, while remaining stable in Culex tarsalis cultures.
- Anti-SLE virus antibodies reduced viral production in Culex tarsalis cultures, with one culture cured, but had no effect on Aedes cultures.
Conclusions:
- Persistent flavivirus infections in mosquito cell lines exhibit distinct characteristics based on cell line origin.
- Differences in viral titer dynamics and antibody responsiveness suggest varied regulatory mechanisms of viral replication.
- These findings highlight significant differences in the maintenance of flavivirus persistent infections across mosquito species.