Ornithodoros lahorensis as a biological vector of African swine fever virus.

Abstract

African swine fever virus (ASFV), the sole known DNA arbovirus, causes acute hemorrhagic fever in domestic pigs with case fatality rates approaching case fatality 100%. While less contagiously transmitted than viral agents like foot-and-mouth disease virus, ASFV's epidemiological significance stems from its complex transmission ecology involving soft ticks. Ornithodoros ticks are established biological vectors, with eight species confirmed globally. However, potential vectors in China, where Ornithodoros lahorensis (O. lahorensis) is endemic and remain uncharacterized. This study tested the hypothesis that O. lahorensis serves as a competent biological vector for ASFV under laboratory conditions. We hypothesized that vector competence, defined as the ability to acquire, maintain, and transmit infectious African swine fever virus, differs between soft (O. lahorensis, Argas persicus) and hard (H. longicornis, R. sanguineus, D. silvarum) tick species, and tested this using experimental transmission assays. Results demonstrated that O. lahorensis efficiently supported transstadial persistence and transovarial transmission of ASFV. Naïve pigs exposed to infected O. lahorensis developed acute ASF with case fatality 100%. Viral replication in salivary glands, midgut, and Malpighian tubules was confirmed by qPCR and transmission electron microscopy, with no significant fitness costs to ticks. In contrast, A. persicus and all ixodid species failed to transmit. Here identifies O. lahorensis as a critical ASFV vector in China, informing targeted acaricidal control in endemic regions.