Low vector competence in sylvatic mosquitoes limits Zika virus to initiate an enzootic cycle in South America

Abstract

Zika virus (ZIKV) has spread in the Americas since 2015 and the potential establishment of a sylvatic transmission cycle in the continent has been hypothesized. We evaluated vector competence of five sylvatic Neotropical mosquito species to two ZIKV isolates. Distinct batches of Haemagogus leucoceleanus, Sabethes albiprivus, Sabethes identicus, Aedes terrens and Aedes scapularis females were respectively orally challenged and inoculated intrathoracically with ZIKV. Orally challenged mosquitoes were refractory or exhibited low infection rates. Viral dissemination was detected only in Hg. leucocelaenus, but with very low rates. Virus was not detected in saliva of any mosquito orally challenged with ZIKV, regardless of viral isolate and incubation time. When intrathoracically injected, ZIKV disseminated in high rates in Hg. leucocelaenus, Sa. identicus and Sa. albpiprivus, but low transmission was detected in these species; very low dissemination and no transmission was detected in Ae. terrens and Ae. scapularis. Together these results suggest that genetically determined tissue barriers, especially in the midgut, play a vital role in inhibiting ZIKV for transmission in the tested sylvatic mosquito species. Thus, an independent enzootic transmission cycle for ZIKV in South America is very unlikely.

Survey on Non-Human Primates and Mosquitoes Does not Provide Evidences of Spillover/Spillback between the Urban and Sylvatic Cycles of Yellow Fever and Zika Viruses Following Severe Outbreaks in Southeast Brazil

“…Noteworthy, during a ZIKV outbreak in Guadeloupe and French Guiana, we succeed in detecting ZIKV in urban mosquitoes with the same high throughput system [35]. Sylvatic Neotropical mosquitoes belonging to six species and three genera that have been experimentally challenged with three ZIKV isolates thus far were refractory or exhibited low infection rates [67,68]. Therefore, considering the low vectorial competence of sylvatic mosquitoes tested thus far, coupled with the short, low and asymptomatic viremia of experimentally injected NHPs [69,70], and the fact that recent evidence has concentrated their findings in urban or periurban environments, we assume that there are still no reasons to suppose that ZIKV has established an independent sylvatic cycle in the forests of the RJ and surroundings in Southeast Brazil.…”

From Anonymous to Public Enemy: How Does a Mosquito Become a Feared Arbovirus Vector?

“…The evolutionary history of Haemagogus genus mosquitoes, which are only found in the New World, is not well known. Phylogenetically, they seem to be quite close to the Aedes (Figure 1), which may explain their ability to transmit, more or less, the same viruses as Aedes aegypti: yellow fever, dengue [16], Zika [17], and chikungunya [18], all introduced into South America. New cycles of jungle yellow fever have thus developed, involving South American primates and tree-dwelling Haemagogus mosquitoes.…”

Understanding the role of arthropod vectors in the emergence and spread of plant, animal and human diseases. A chronicle of epidemics foretold in South of France

“…New cycles of jungle yellow fever have thus developed, involving South American primates and tree-dwelling Haemagogus mosquitoes. Phylogenetically, the genus Haemagogus seems to be quite close to Aedes [9], which may explain the ability of Haemagogus species to often transmit the same viruses: yellow fever, dengue [10], Zika [11], and chikungunya [12], all introduced into South America.…”

“…De nouveaux cycles forestiers de fièvre jaune se sont ainsi développés, impliquant des primates sud-américains et des moustiques Haemagogus, dont les larves se développent dans les creux d'arbres. Phylogénétiquement, le genre Haemagogus parait être assez proche du genre Aedes [9], ce qui pourrait expliquer la capacité des Haemagogus à souvent transmettre les mêmes virus : fièvre jaune, dengue [10], Zika [11], et chikungunya [12], tous introduits en Amérique du Sud.…”