Highly Efficient Vertical Transmission for Zika Virus in Aedes aegypti after Long Extrinsic Incubation Time

Abstract

While the Zika virus (ZIKV) 2014–2017 pandemic has subsided, there remains active transmission. Apart from horizontal transmission to humans, the main vector Aedes aegypti can transmit the virus vertically from mother to offspring. Large variation in vertical transmission (VT) efficiency between studies indicates the influence of parameters, which remain to be characterized. To determine the roles of extrinsic incubation time and gonotrophic cycle, we deployed an experimental design that quantifies ZIKV in individual progeny and larvae. We observed an early infection of ovaries that exponentially progressed. We quantified VT rate, filial infection rate, and viral load per infected larvae at 10 days post oral infection (d.p.i.) on the second gonotrophic cycle and at 17 d.p.i. on the second and third gonotrophic cycle. As compared to previous reports that studied pooled samples, we detected a relatively high VT efficiency from 1.79% at 10 d.p.i. and second gonotrophic cycle to 66% at 17 d.p.i. and second gonotrophic cycle. At 17 d.p.i., viral load largely varied and averaged around 800 genomic RNA (gRNA) copies. Longer incubation time and fewer gonotrophic cycles promoted VT. These results shed light on the mechanism of VT, how environmental conditions favor VT, and whether VT can maintain ZIKV circulation.

Evidence of Zika virus horizontal and vertical transmission in Aedes albopictus from Spain but not infectious virus in saliva of the progeny

“…A recent study conducted with orally infected Ae. aegypti mosquitoes with Asian ZIKV lineage has shown that VT moderately decreased with gonotrophic cycles [18], which would agree with our results in Ae. albopictus, since we found higher prevalence in E1 progeny than in the E2 progeny.…”

“…Moreover, ZIKV VT has also been experimentally demonstrated in Ae. aegypti [16][17][18] and Ae. albopictus mosquitoes [17]; and venereal transmission, in Ae.…”

Survival and Replication of Zika Virus in Diapause Eggs of Aedes Albopictus From Beijing, China

“…It was worth noting that diapause eggs under SD photoperiod had a relative higher infection rate before 7 dpov and then MIR on 70 dpov would have been minimal, even zero, in GC1, suggesting that the virus infectivity and RNA copy number decreased with time and no virus replication occurred in the eggs finally. These results corroborated the findings of a great deal of previous work (Manuel et al, 2020 ). Despite the trend of rapid decreasing MIRs, vertical transmission was observed during GC1 (Chaves et al, 2019 ).…”

Interspecies Isobaric Labeling-Based Quantitative Proteomics Reveals Protein Changes in the Ovary of Aedes aegypti Coinfected With ZIKV and Wolbachia

“…During infection in female mosquitoes, the virus can be located in different tissues, but mainly in the gut, salivary glands, and ovaries ( Sá-Guimarães et al., 2021 ). Ovaries infection is of paramount importance to maintain the vertical transmission of arboviruses, even if at low rates ( Thangamani et al., 2016 ; Manuel et al, 2020 ; Nag et al., 2021 ). Therefore, evaluating physiological and molecular changes in mosquito ovaries due to arbovirus infection, especially those affecting life-history traits related to vertical transmission, might provide new insights to design innovative vector control approaches.…”