Evidence of Experimental Vertical Transmission of Emerging Novel ECSA Genotype of Chikungunya Virus in Aedes aegypti

Abstract

BackgroundChikungunya virus (CHIKV) has emerged as one of the most important arboviruses of public health significance in the past decade. The virus is mainly maintained through human-mosquito-human cycle. Other routes of transmission and the mechanism of maintenance of the virus in nature are not clearly known. Vertical transmission may be a mechanism of sustaining the virus during inter-epidemic periods. Laboratory experiments were conducted to determine whether Aedes aegypti, a principal vector, is capable of vertically transmitting CHIKV or not.Methodology/Principal FindingsFemale Ae. aegypti were orally infected with a novel ECSA genotype of CHIKV in the 2nd gonotrophic cycle. On day 10 post infection, a non-infectious blood meal was provided to obtain another cycle of eggs. Larvae and adults developed from the eggs obtained following both infectious and non-infectious blood meal were tested for the presence of CHIKV specific RNA through real time RT-PCR. The results revealed that the larvae and adults developed from eggs derived from the infectious blood meal (2nd gonotrophic cycle) were negative for CHIKV RNA. However, the larvae and adults developed after subsequent non-infectious blood meal (3rd gonotrophic cycle) were positive with minimum filial infection rates of 28.2 (1∶35.5) and 20.2 (1∶49.5) respectively.Conclusion/SignificanceThis study is the first to confirm experimental vertical transmission of emerging novel ECSA genotype of CHIKV in Ae. aegypti from India, indicating the possibilities of occurrence of this phenomenon in nature. This evidence may have important consequence for survival of CHIKV during adverse climatic conditions and inter-epidemic periods.

Rift Valley fever virus: strategies for maintenance, survival and vertical transmission in mosquitoes

“…Yolk formation in the developing oocytes, termed vitellogenesis, is initiated immediately after ingestion of a blood meal so orally ingested virus must replicate rapidly to be transmitted within the same ovarian cycle. The expansion of the ovaries during oogenesis may also increase the permeability of tissue to virus, contributing to increased VT in subsequent cycles [103]. Absence of virus in the first gonotrophic cycle has been observed for chikungunya virus (Alphavirus), [103] and YFV [104].…”

“…The expansion of the ovaries during oogenesis may also increase the permeability of tissue to virus, contributing to increased VT in subsequent cycles [103]. Absence of virus in the first gonotrophic cycle has been observed for chikungunya virus (Alphavirus), [103] and YFV [104]. This contrasts with the detection of LACV and CEV in the progeny of Aedes spp.…”

Detection of Persistent Chikungunya Virus RNA but not Infectious Virus in Experimental Vertical Transmission in Aedes aegypti from Malaysia

“…For comparison, previous studies of vertical transmission of CHIKV in Aedes mosquitoes were summarized ( Table 2). RT-PCR was the most common method used to detect CHIKV, in seven of nine studies, 8,9,14,18,[20][21][22] and only one of those failed to detect CHIKV RNA. 22 RNA detection rates otherwise ranged between 0.4% and 100%, in both experimentally and naturally infected samples.…”

“…Progeny adult homogenates were also analyzed by RT-PCR targeting the region encoding E1 and plaque assay. The eggs from the first gonotrophic cycle were not examined as vertical transmission is more likely to occur in second and subsequent cycles following infection with CHIKV, 14 probably due to a longer extrinsic incubation period allowing replication in the ovaries.…”

Arbovirosis Transmitidas Por Mosquitos (Diptera: Culicidae) en La República Dominicana: Una Revisión

“…aegypti y Ae. albopictus, cuya sinantropia y antropofilia comportan altos niveles de exposición humana al virus, teniendo además en consideración que en ambas se ha verificado la transmisión vertical del CHIKV (Agarwal et al, 2014). Los seres humanos constituyen el principal reservorio del virus durante los períodos epidémicos.…”