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Transmission of Northway and St. Louis encephalitis viruses by arctic mosquitoes
Abstract:
Transmission of a Canadian arctic isolate of Northway virus has been demonstrated after incubation of arctic Aedes communis mosquitoes at 13 degrees C for 27 days after intrathoracic injection of 300 plaque forming units of virus. Replication has also been demonstrated after intrathoracic injection of domestic A. aegypti mosquitoes of this virus. Virions of Northway virus, 84--92 nm diameter were morphologically typical of a bunyavirus after propagation in salivary glands of A. communis or in tissue cultures of baby hamster kidney (BHK-21) cells. An Ontario isolate of St. Louis encephalitis was transmitted by bites of A. communis after 27 days incubation at 13 degrees C after oral ingestion of 3 or 30 mouse LD50 virus. This mosquito species transmitted virus after 13 to 76 days incubation at 13 degrees C following intrathoracic injection of 3 mouse LD50 or higher virus doses.
Insights
Northway virus can infect and replicate in Aedes communis mosquitoes, demonstrating potential for transmission. St. Louis encephalitis virus was also transmitted by these mosquitoes under experimental conditions.
Area of Science:
- Arbovirology
- Medical Entomology
- Virology
Background:
- Northway virus is an arbovirus found in the Canadian Arctic.
- Mosquitoes are important vectors for arboviruses, transmitting them to hosts.
Purpose of the Study:
- To investigate the transmission capability of Northway virus in mosquitoes.
- To assess the vector competence of Aedes communis for Northway virus and St. Louis encephalitis virus.
Main Methods:
- Intrathoracic injection and oral feeding of viruses into Aedes communis and Aedes aegypti mosquitoes.
- Incubation of infected mosquitoes at 13°C for extended periods.
- Morphological analysis of virus particles in mosquito salivary glands and cell cultures.
Main Results:
- Northway virus replicated and was transmitted by Aedes communis mosquitoes after incubation at 13°C.
- St. Louis encephalitis virus was transmitted by Aedes communis after oral ingestion and intrathoracic injection, with prolonged incubation periods at 13°C.
Conclusions:
- Aedes communis mosquitoes are capable of transmitting Northway virus.
- The findings suggest a potential role for Aedes communis in the enzootic cycle of Northway virus and highlight its competence as a vector for other arboviruses like St. Louis encephalitis virus.