Persistent viruses in mosquito cultured cell line suppress multiplication of flaviviruses

Abstract

In the growth kinetics analysis of flaviviruses in Aedes albopictus C6/36 cell lines obtained from the Japanese Collection of Research Bioresources (JCRB) Cell Bank and the European Collection of Authenticated Cell Culture (ECACC), these two cells line showed different viral susceptibility for Zika virus (ZIKV), Dengue virus (DENV), and Japanese encephalitis virus (JEV). Next-generation sequencing (NGS) analysis revealed that the C6/36 JCRB strain was persistently infected with two viruses without showing any cytopathic effects. The complete sequence analysis demonstrated that the one virus was Menghai rhabdovirus (MERV), which has been found from Aedes albopictus mosquito. The other virus was a novel virus, designated as Shinobi tetravirus (SHTV). Interestingly, the viral susceptibility of these two strains was almost even for Sindbis virus and Getah virus. We cloned SHTV and MERV from JCRB C6/36 cell line and then re-infected them into another C6/36 cell line, resulting in the reproduction of persistent infection with each virus. ZIKV growth was suppressed in SHTV and/or MERV re-infected C6/36 cells also. To our knowledge, this is the first demonstration that persistent infection with rhabdovirus and/or permutotetravirus suppressed flavivirus replication in mosquito cells.

Differential small RNA responses against co-infecting insect-specific viruses in Aedes albopictus mosquitoes

“…Only female carcasses allowed relatively high SHTV replication while AEFV and MERV RNA levels were comparable between both females and males carcasses. This is in agreement with a previous report showing that these ISVs do not compete with each other during infection in mosquito C6/36 cell line [14].…”

“…Recent metagenomics studies have shed light on the virome of these mosquito vectors, revealing diverse virus communities largely composed of insect-specific viruses (ISVs) that specifically infect invertebrates but not vertebrates [1-7]. ISVs have been shown to negatively regulate some arbovirus infections in mosquito cell cultures and in vivo [8-14]. For instance, two ISVs, Menghai rhabdovirus (MERV) and Shinobi tetravirus (SHTV), which were identified in an Aedes ( Ae .)…”

“…For instance, two ISVs, Menghai rhabdovirus (MERV) and Shinobi tetravirus (SHTV), which were identified in an Aedes ( Ae .) albopictus C6/36 cell line from the Japanese Collection of Research Bioresources (JCRB), suppressed Zika virus replication in vitro [14]. In spite of increased attention to ISVs, little is known about mosquito-ISV interactions, from the natural infection routes in vivo to the immune responses to ISVs.…”

Dianke virus: A new mesonivirus species isolated from mosquitoes in Eastern Senegal

“…Like our study where a large diversity of vectors was infected by the new strain, several studies have detected mesonivirus infection of mosquitoes with potentially significant health impacts (Zirkel et al, 2011;Nga et al, 2011;Vasilakis et al, 2014). Indeed, it has been shown that dual viral infections in mosquito can alter viral infectivity (Fujita et al, 2018) and ISVs are more and more considered as potential disease control agents in vector populations (Guzman et al, 2018;Öhlund et al, 2019). Virus phenotypic restriction could be more complex as Parry and Asgari (2018) highlighted that restriction of Dengue virus replication in Ae.aegypti mosquitoes could be hindered by interactions between a novel ISV and the endosymbiotic bacterium Wolbachia pipientis.…”

Aedes aegypti (Aag2)-derived clonal mosquito cell lines reveal the impact of pre-existing persistent infection with the insect-specific bunyavirus Phasi Charoen-like virus on arbovirus replication

“…This highlights the differential effects persistent and acute insect-specific virus infections can have on arbovirus replication. Meanwhile, Fujita et al showed that persistent infection with Shinobi tetravirus (SHTV; family Permutotetraviridae ) and Menghai rhabdovirus (MERV; family Rhabdoviridae ) alone and in combination reduce ZIKV replication in C6/36 cells, with the two viruses combined also suppressing the replication of the flaviviruses DENV and Japanese encephalitis virus (JEV) [39]. Both studies may not fully recapitulate the conditions encountered in nature, since C6/36 cells are immunocompromised [43], and the mosquito immune system is known to pose a barrier to arboviral infection, within-vector dissemination and transmission [44-48], and is a known contributor to the observed variability in vector competence [44,47].…”