Natural infection and vertical transmission of two flaviviruses (Yellow fever and Zika) in mosquitoes in primary forests in the Brazilian state of Rio de Janeiro (Diptera: Culicidae)

Abstract

27 Background: Zika virus (ZIKV) was recently introduced in the American continent, 28 probably transmitted by Aedes aegypti and possibly by Ae. albopictus and Culex 29 quinquefasciatus in urban environments. ZIKV represents a known public health 30 problem as it has been involved in newborn cases of congenital microcephaly in South 31 America since 2005. The transmission of this virus in forested areas of other countries 32 and its relative ubiquity in relation to its vectors and reservoirs raises suspicions of its 33 adaptation to non-human modified environments (i.e., natural forests reserve) or on this 34 continent, similar to those seen for Yellow fever virus (YFV). The objective of this 35 work was to have an epidemiological monitoring tool mapping insects as well as 36 circulating arboviruses in wild areas with low human interference. This study was based 37 on the history of the insect flavivirus spreading cycle. Methods/Principal Findings: 38 Using a previously described sensitive PCR-based assay to assess the conserved NS5 39 region of the Flavivirus genus, both YFV partial genome and ZIKV were found in pools 40 of Aedes albopictus, a sylvatic mosquito adapted to human-modified environments, and 41 in Haemagogus leucocelaenus, a sylvatic mosquito. Conclusions: This is the first report 42 of natural infection by ZIKV in mosquitoes in a sylvatic environment on the American 43 continent. The wide distribution of these mosquitoes is probably important in the 44 transmission of ZIKV. Vertical transmission indicates a higher efficiency for the 45 maintenance and transmission of the virus in nature as well as the presence of the ZIKV 46 in permanent character in the forest areas as it occurs with the YFV thus making more 47 difficult the prevention of new cases of Zika in humans.48 49 50 3 51 Author Summary 52 Arboviruses are diseases transmitted by arthropod vectors, hence the origin of the term 53 ARthropod BOrne VIRUS, which is adopted since 1942. This work had as objective to 54 survey the circulating insects as well as to detect the presence of viruses in them. 55 Arboviruses circulate between insects and vertebrate hosts, having importance for 56 promoting diseases in humans and animals. The diseases most known at the time, due to 57 the recent cases reported by South America, are Dengue, Zika, Yellow Fever and 58 Chikungunya. For this study, we used appropriate traps to collect the insects and their 59 eggs in wild areas where there is little human interference. After collection, mosquitoes 60 and / or eggs were identified and separated as to the source and species. The eggs were 61 kept in laboratory conditions for the hatching of new insects. All the insects obtained 62 were separated into pools to be macerated and thus extract the RNA from the viruses to 63 be studied. Using molecular biology techniques, in our case the RT-PCR (Reverse 64 Transcriptase Polymerase Chain Reaction), we amplified the RNA and in sequentially, 65 we performed the sequencing reaction. With sequencing, it is possible to iden...

The Absence of Yellow Fever in Asia: History, Hypotheses, Vector Dispersal, Possibility of YF in Asia, and Other Enigmas

“…furcifer-taylori males in Africa [210] and from nulliparous Haemagogus janthinomys females and Hg. leucocelaenus in Brazil [211,212]. The conclusions of many studies and reviews, while acknowledging occurrence of VT in nature, have been that this mode of transmission is mathematically insufficiently robust to sustain virus and, thus, epidemiologically insignificant or that its role in virus maintenance is questionable [209,213,214].…”

Infection of the maternal-fetal interface and vertical transmission following low-dose inoculation of pregnant rhesus macaques (Macaca mulatta) with an African-lineage Zika virus

“…Of the two distinct genetic lineages of ZIKV, only Asian-lineage ZIKV is currently associated with congenital infection in humans [ 13 ]. Recently, African-lineage ZIKV has been reportedly detected in Brazil [Preprints 14 , 15 ], however these data have yet to be published. The potential novel detection of African-lineage ZIKV outside the African continent demonstrates the possibility of a new outbreak and underscores the need to further evaluate the threat that African-lineage ZIKV poses to pregnant people.…”