Laboratory Assessment of Vector Competence of Phlebotomus Duboscqi to a Novel Sandfly-associated Phlebovirus

Abstract

Phleboviruses transmitted by sand flies are among emerging public health threats. A novel Phlebovirus named Ntepes virus (NPV) was recently described in Kenya and found to infect humans from a wider geographic area. However, the entomologic risk factors such as potential vectors and transmission efficiency remains poorly defined. This study assessed the ability of the sand fly Phlebotomus duboscqi to transmit NPV. Two hundred and five 5-day old laboratory colonized P. duboscqi were exposed to NPV by membrane feeding in a triplicate experiment with a viremic blood meal of a dose of about 106.0pfu/ml. All the 205 NPV-exposed sandflies were randomly picked on the 6th, 10th and 15th days post infection and individually dissected into abdomens, legs and salivary glands to test for mid-gut infection, disseminated infection and transmissible infection, respectively, by cell culture. Of the 205 NPV-exposed sandflies, 40 (19.51%) developed infections which were all limited to the mid gut and that did not disseminate to the legs nor the salivary glands. Mid gut infection rates decreased with increasing extrinsic incubation period (Spearman’s correlation, ρ= -0.7145). These findings signify that P. duboscqi is an incompetent laboratory vector of NPV from ingestion of a viremic blood meal since the mid gut infections did not disseminate to the salivary glands to be transmitted by bites.