Transmission competence of a new mesonivirus, Yichang virus, in mosquitoes and its interference with representative flaviviruses

Abstract

Advances in technology have greatly stimulated the understanding of insect-specific viruses (ISVs). Unfortunately, most of these findings are based on sequencing technology, and laboratory data are scarce on the transmission dynamics of ISVs in nature and the potential effects of these viruses on arboviruses. Mesonivirus is a class of ISVs with a wide geographical distribution. Recently, our laboratory reported the isolation of a novel strain of mesonivirus, Yichang virus (YCV), from Culex mosquitoes, China. In this study, the experimental infection of YCV by the oral route for adult and larvae mosquitoes, and the vertical transmission has been conducted, which suggests that YCV could adopt a mixed-mode transmission. Controlled experiments showed that the infectivity of YCV depends on the mosquito species, virus dose, and infection route. The proliferation curve and tissue distribution of YCV in Cx. quinquefasciatus and Ae. albopictus showed that YCV is more susceptible to Ae. albopictus and is located in the midgut. Furthermore, we also assessed the interference of YCV with flaviviruses both in vitro and in vivo. YCV significantly inhibited the proliferation of DENV-2 and ZIKV, in cell culture, and reduced transmission rate of DENV-2 in Ae. albopictus. Our work provides insights into the transmission of ISVs in different mosquito species during ontogeny and their potential ability to interact with mosquito-borne viruses.

Symbiotic Interactions Between Mosquitoes and Mosquito Viruses

“…In the absence of this obvious horizontal transmission cycle, these mosquito viruses were generally assumed to be transmitted vertically. However, experimental evidence for such vertical transmission is rare ( Bolling et al., 2011 ; Saiyasombat et al., 2011 ; Bolling et al., 2012 ; McLean et al., 2020 ; Ye et al., 2020 ). For instance, Cx.…”

“…To date, horizontal transmission via food sources in adult mosquitoes has only been tested through blood-feeding for a handful of viruses belonging to the flavivirus, negevirus, alphavirus and mesonivirus genera. Transmission through infected blood meals was not successful for the tested flaviviruses (CxFV, Palm Creek virus) ( Kent et al., 2010 ; Hall-Mendelin et al., 2016 ) but was possible for an alphavirus (Eilat virus) and a mesonivirus (Yichang virus), in case of high virus titres ( Vasilakis et al., 2013 ; Nasar et al., 2014 ; Ye et al., 2020 ). Mosquitoes can also be horizontally infected during larval stages, although only a few studies have been performed for RNA viruses.…”

“…Mosquitoes can also be horizontally infected during larval stages, although only a few studies have been performed for RNA viruses. For instance, Kamiti River virus (KRV, Flaviviridae ) and the Yichang virus can infect larvae when added to rearing water; although this was not the case for CxFV ( Lutomiah et al., 2007 ; Bolling et al., 2012 ; Ye et al., 2020 ). However, the same strain of CxFV has been found in Cx.…”

“…So far, only a mesonivirus (Yichang virus) has been shown to interfere with an arbovirus from a different family (DENV, Flaviviridae ) in vitro and reduce its transmission rate in Ae. albopictus ( Ye et al., 2020 ). In contrast to mosquito RNA viruses, DNA viruses have rarely been studied for their interactions with arboviruses.…”

Spatial scale influences taxon conservation in the eukaryotic virome of a mosquito

“…These viruses are mostly RNA viruses, the dominant group in terrestrial eukaryotes (16), and are thought to be mosquito commensals that do not infect vertebrates (17). Moreover, they are often supposed to be vertically transmitted, although other transmission modes have been observed (18)(19)(20)(21). Interestingly, a few mosquito-specific viruses have been shown to influence the infection of mosquitoes by human pathogens under laboratory conditions (21)(22)(23)(24)(25)(26).…”