Natural vertical infection by dengue virus serotype 4, Zika virus and Mayaro virus in Aedes (Stegomyia) aegypti and Aedes (Stegomyia) albopictus

Abstract

Vertical transmission to progeny ensures the maintenance of arboviruses in their natural vectors. This mechanism is largely reported for dengue virus (DENV) and yellow fever virus (YFV). Few studies have addressed this mechanism for Zika virus (ZIKV), Mayaro virus (MAYV) and other arboviruses. The present study investigated the natural infection rate by arboviruses in 4490 Aedes (Stegomyia) aegypti and 296 Aedes (Stegomyia) albopictus (Diptera: Culicidae) reared from eggs collected with ovitraps in Cuiabá, Mato Grosso State, from February to July, 2017. After viral RNA extraction and reverse transcriptase‐polymerase chain reaction protocols for 10 flaviviruses and five alphaviruses, nucleotide sequencing and three passages in C6/36 cells, eight pools of Ae. aegypti positive for DENV‐4 genotype II, seven for ZIKV Asian genotype and two for MAYV genotype L were found. In addition, two Ae. albopictus pools were positive for DENV‐4 genotype II and two were positive for ZIKV Asian genotype. Infection was confirmed by viral isolation in all positive pools for DENV‐4 and for MAYV and in eight of nine for ZIKV. This mechanism may contribute to the spread of arboviruses during epidemics and also to their maintenance in natural vectors during interepidemic periods.

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

“…aegypti [12][13][14]. ZIKV was also repeatedly detected in eggs and larvae collected in urban and forested environments [15][16][17][18]. However, a few other studies report an absence of VT in the laboratory or lack of detection in immature stages in the field [19,20].…”

Silent circulation of dengue virus in Aedes albopictus (Diptera: Culicidae) resulting from natural vertical transmission

“…Natural vertical transmission of DENV in Ae. aegypti has been demonstrated in the states of Minas Gerais 35,[37][38][39] , Pernambuco 40 , Ceará 36 , Mato Grosso [40][41][42] Rio de Janeiro 43 and Amazonas 44 .…”

Mayaro Virus Pathogenesis and Transmission Mechanisms

“…Vertical transmission was revealed by the isolation of MAYV from two pools of adult Ae. aegypti which were collected from the egg stage in Brazil in 2017 [89]. Further studies are needed to identify the importance of vertical transmission during epidemics and the molecular mechanism that underlies viral maintenance in the vectors during unfavorable periods [90].…”

“…It is, however, clear that the effectiveness of this mechanism depends on climate change, geographical location, arbovirus genotype, and vector population dynamics [91]. Although this mechanism has been extensively reported for DENV, CHIKV, ZIKV, and Yellow fever virus infections [92][93][94][95], very few studies have addressed its role in MAYV and other arboviruses [89]. Airborne transmission of MAYV has also been reported among laboratory personnel [96].…”