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Isolation and characterization of Midway virus: a new tick-borne virus related to Nyamanini
Abstract:
Midway virus, a new tick-borne virus isolated from two species of Ornithodoros (Alectorobius) ticks of the capensis group (O capensis, O denmarki), is described from Midway, Kure, and Manana islands in the Central Pacific (Hawaiian Archipelago) and from northern Honshu (Japan). Midway virion is enveloped, unusually large, acid and temperature sensitive, and its type of nucleic acid is RNA. Complement-fixation (CF) tests show a close relation of Midway to Nyamanini virus, which has been isolated from ardeid birds and Argas ticks in Africa, the Indian subcontinent, and Southeastern Asia. However, cross-box tests (CF, mouse and tissue culture neutralization, immunofluorescence) show that these two viruses are quite distinct. Midway virus is lethal for newborn Swiss mice inoculated by intracerebral, but not intraperitoneal route. It fails to kill four-week-old mice by either route. Midway virus causes cytopathic effects in BHK-21 cells and titerable plaques in Vero cells. Antibodies to it were prevalent among nestlings of Larus crassirostris (Black-tailed Gull) on Aomatsushima I., but were scarce among those of Nycticorax nycticorax (Black-crowned Night Heron) of the same island.
Insights
A new tick-borne virus, Midway virus, was identified in the Pacific and Japan. This novel RNA virus is lethal to newborn mice and shows distinct characteristics from related viruses.
Area of Science:
- Virology
- Arthropod-borne Diseases
- Epidemiology
Background:
- Tick-borne viruses pose significant public health risks.
- The discovery of novel viruses is crucial for understanding disease transmission.
- Ornithodoros ticks are known vectors for various pathogens.
Purpose of the Study:
- To describe a newly isolated tick-borne virus, named Midway virus.
- To characterize the biological and physical properties of Midway virus.
- To investigate the relationship between Midway virus and other known viruses.
Main Methods:
- Isolation of virus from Ornithodoros ticks collected from Pacific islands and Japan.
- Electron microscopy and nucleic acid analysis for virion characterization.
- Complement-fixation, neutralization, and immunofluorescence assays for serological relatedness.
- Mouse inoculation studies and cell culture experiments (BHK-21, Vero) to assess pathogenicity and cytopathic effects.
- Serological surveys in bird populations.
Main Results:
- Midway virus, an enveloped, large, acid and temperature-sensitive RNA virus, was isolated.
- Complement-fixation tests indicated a relationship with Nyamanini virus, but cross-neutralization tests confirmed they are distinct.
- Midway virus was lethal to newborn mice via intracerebral inoculation but not to older mice.
- Cytopathic effects and plaques were observed in BHK-21 and Vero cell cultures, respectively.
- Antibodies were prevalent in Black-tailed Gull nestlings but scarce in Black-crowned Night Herons.
Conclusions:
- Midway virus represents a novel tick-borne pathogen.
- The virus exhibits distinct serological and pathogenic properties.
- Further research is needed to understand the ecology and public health implications of Midway virus.