Related Experiment Videos
A variant of La Crosse virus attenuated for Aedes triseriatus mosquitoes
Abstract:
A plaque-purified variant was cloned from prototype La Crosse (LAC) virus. This variant (PP-31) was lethal to suckling mice by the intracerebral route, produced "wild-type" plaques in Vero and BHK-21 cells, and grew to high titers (greater than 10(7) PFU/ml) in suckling mice and in cell culture. The variant was able to orally infect the vector, Aedes triseriatus; however, it was unable to escape infected midgut cells and disseminate to secondary target organs. Large, atypical, focal accumulations of viral antigen were detected in these midguts by immunofluorescence. Orally infected mosquitoes were unable to transmit virus by bite to suckling mice or vertically to their progeny. Even after inoculation of the variant virus into mosquitoes, there appeared to be a restriction on cell to cell virus movement. The role such variants may play in the modulation of infection in an arthropod vector is discussed.
Insights
A plaque-purified variant of La Crosse virus (PP-31) was lethal to mice but could not spread within mosquitoes. This variant highlights how viral strains can be restricted in arthropod vectors, impacting disease transmission.
Area of Science:
- Virology
- Arthropod-borne viruses
- Viral pathogenesis
Background:
- La Crosse virus (LAC) is a significant cause of pediatric arboviral encephalitis in North America.
- Understanding viral variants and their interactions with vectors is crucial for predicting and controlling disease outbreaks.
Purpose of the Study:
- To characterize a plaque-purified variant (PP-31) of La Crosse virus.
- To investigate the replication, dissemination, and transmission capabilities of the PP-31 variant in a mammalian host and its primary vector, Aedes triseriatus.
Main Methods:
- Plaque purification of La Crosse virus.
- Intracerebral inoculation of suckling mice.
- Oral infection of Aedes triseriatus mosquitoes.
- Immunofluorescence assays to detect viral antigen.
- Virus titration in cell culture and mosquitoes.
Main Results:
- The PP-31 variant was lethal to suckling mice and replicated to high titers in mice and cell culture.
- Oral infection of Aedes triseriatus mosquitoes with PP-31 resulted in midgut infection but failed dissemination to secondary organs.
- Large, atypical accumulations of viral antigen were observed in mosquito midguts.
- PP-31 was not transmitted by orally infected mosquitoes via bite or vertically.
- Even after direct inoculation into mosquitoes, cell-to-cell virus movement appeared restricted.
Conclusions:
- The PP-31 variant exhibits a significant defect in its ability to propagate within the Aedes triseriatus vector.
- This defect in vector dissemination and transmission suggests that specific viral variants can be modulated within arthropod hosts.
- Such vector-specific restrictions may play a role in regulating the epizootic potential of La Crosse virus.