Abundance of Phasi-Charoen-like virus in Aedes aegypti mosquito populations in different states of India

Abstract

Mosquitoes are known to harbor a large number of insect specific viruses (ISV) in addition to viruses of public health importance. These ISVs are highly species specific and are non-pathogenic to humans or domestic animals. However, there is a potential threat of these ISVs evolving into human pathogens by genome alterations. Some ISVs are known to modulate replication of pathogenic viruses by altering the susceptibility of vector mosquitoes to pathogenic viruses, thereby either inhibiting or enhancing transmission of the latter. In the present study, we report predominance of Phasi Charoen-like virus (PCLV, Family: Phenuviridae) contributing to >60% of the total reads in Aedes aegypti mosquitoes collected from Pune district of Maharashtra state using next generation sequencing based metagenomic analysis of viromes. Similar results were also obtained with mosquitoes from Assam, Tamil Nadu and Karnataka states of India. Comparison of Pune mosquito sequences with PCLV Rio (Brazil) isolate showed 98.90%, 99.027% and 98.88% homologies in the S, M and L segments respectively indicating less genetic heterogeneity of PCLV. The study also demonstrated occurrence of transovarial transmission as seen by detection of PCLV in eggs, larvae, pupae and male mosquitoes. Ae. aegypti mosquitoes collected from Pune also showed a large number of reads for viruses belonging to Baculoviridae, Rhabdoviridae, Genomoviridae and Bunyaviridae families. The role of PCLV in the replication of dengue and chikungunya virus is yet not clear. It warrants further studies to know the significance of PCLV and other ISVs on the replication and transmission of Ae. aegypti borne pathogenic viruses, especially in the absence of prophylactics or therapeutics.

Metagenomic Analysis of Viromes of Aedes Mosquitoes across India

“…Akin to our previous report [ 13 ], a large proportion of the reads was assigned to Homo sapiens , ranging from 4566 reads to 167,340 reads across all the viromes. In the previous study, we used the Centrifuge v1.0.4 database for metagenomic taxa assignment, whereas in this one, the EPI2ME Portal’s classification system (Kraken2) was used.…”

“…Pools of 20 adult female mosquitoes were processed for sequencing library preparation according to a previously published protocol [ 13 ], with a few modifications. In brief, mosquitoes were washed with sterile MilliQ water and homogenized in liquid nitrogen using a sterile mortar and pestle.…”

“…A maximum of 100 nanograms (ng) RNA was used for first-strand cDNA synthesis, followed by RNaseH treatment. Second-strand synthesis using Klenow fragment and Sequence-independent single-primer amplification (SISPA) [ 14 ] were carried out as described earlier [ 13 ]. The primers used for SISPA are given in Table 1 .…”

“…In a previous study, we reported an abundance of Phasi Charoen-like phasivirus (PCLV) in Ae. aegypti populations throughout India, a country endemic to DENV and CHIKV [ 13 ]. Here, we report the metagenomic analysis of virome constituents of Ae.…”

Transovarial transmission of mosquito-borne viruses: a systematic review

“…Due to a lack of therapeutics or effective vaccines, mosquito-borne viral diseases remain a serious global health threat. Mosquito vectors tend to be anthropophilic and are the primary carriers of a number of viruses, including DENV, ZIKV, CHIKV, and yellow fever ( Lole et al., 2022 ). The yellow fever mosquito ( Aedes aegypti ) and the Asian tiger mosquito ( Ae.…”