Exploring Routes of Infection of Severe Fever with Thrombocytopenia Syndrome Virus Using Experimentally Infected Animals.

Reports from endemic regions in Asia indicate that severe fever with thrombocytopenia syndrome virus (SFTSV), a canonically tick-borne virus, can be directly transmitted from infected humans and animals to naïve hosts. To understand this process, using a feline infection model, we observed that both intramuscular inoculation and oral inoculation resulted in adult cats developing viremia, with cats inoculated intramuscularly shedding virus orally. We also observed a potential organ tropism associated with the route of inoculation. Using an immunodeficient murine model, we further demonstrated that noncanonical routes of inoculation can result in lethal infections. However, we could not replicate the organ tropism seen in cats, possibly because of the immunodeficient nature of the mice. Like cats, mice shed SFSTV orally. These results indicate that SFTSV can exist in a vector-free cycle, highlighting a need for increased surveillance and precautions when handling potentially infected animals.