Experimental Infection of Six Species of Ixodid Ticks with Dugbe Virus (Family Bunyaviridae, Genus Nairovirus)

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  • Disease Assessment Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland
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The vector potential of each of 6 species of colonized North American and African ixodid ticks was assessed by intracoelomic inoculation with Dugbe virus (IbAr 1792, 14th passage in suckling mouse brain) and viral titers were monitored after selected incubation periods. Persistence of Dugbe virus for ≥53 days in 5 species (Dermacentor andersoni, D. variabilis, Amblyomma americanum, Rhipicephalus appendiculatus, and R. sanguineus) indicates that infection occurred. Viral titers were significantly higher in female vs. male D. variabilis, R. appendiculatus, and A. americanum after blood feeding. Blood feeding had no significant effect on the viral titers of either female or male R. sanguineus. D. andersoni males also exhibited no significant change in viral titers after bloodfeeding, but 100% (20/20) of drop-off females and 96% (24/25) of post-oviposition females (36 days postinoculation) contained no detectable virus even though virus was still found in unfed specimens ≤124 days postinoculation. Virus was not recovered from >30,000 1st generation progeny (eggs, larvae, nymphs, adults) collected as eggs from inoculated female D. andersoni, D. variabilis, R. sanguineus, and R. appendiculatus 27–51 days postinoculation. R. sanguineus and R. appendiculatus transmitted Dugbe virus to guinea pigs when allowed to feed 1–3 weeks postinoculation.