Evolution-driven attenuation of alphaviruses highlights key glycoprotein determinants regulating viral infectivity and dissemination

Abstract

Understanding the fundamental mechanisms of arbovirus transmission and pathogenesis is 30 essential to develop new strategies for treatment and prevention. We previously took an in vivo 31 evolution-based approach and identified the chikungunya virus E1 glycoprotein residue 80 to 32 play a critical role in viral transmission and pathogenesis. In this study, we address the genetic 33 robustness and function of position 80 and demonstrate that this highly conserved residue is 34 a key determinant in alphavirus infectivity and dissemination through modulation of viral fusion 35 and cholesterol dependence. In addition, in studying the evolution of position 80, we identified 36 a network of glycoprotein residues, including epidemic determinants, that regulate virus 37 dissemination and infectivity. These studies underscore the importance of taking evolution-38 based approaches to not only identify key viral determinants driving arbovirus transmission 39 and pathogenesis but also to uncover fundamental aspects of arbovirus biology. 40 41 42 43 fusion, viral dissemination. 44 45 46 47 48 49 50 51 52 53 54 55 56the mature virion, E1 and the attachment protein E2 are arranged to form 80 trimeric spikes 87 constituted of trimers of E1-E2 heterodimers (Kielian and Rey, 2006; Sun et al., 2013). These 88 protein complexes then mediate CHIKV internalization by receptor mediated endocytosis and 89 fusion within the early endosome (Hoornweg et al., 2016), where low endosomal pH triggers 90 E1-E2 dissociation, E1 fusion loop insertion into the target membrane, and concomitant 91 membrane fusion (Kielian and Rey, 2006; van Duijl-Richter et al., 2015). 92The CHIKV glycoproteins play a significant role in CHIKV transmission, emergence, 93 and spread. In particular, an adaptive mutation in the CHIKV E1 glycoprotein, A226V, gave 94 rise to the Indian Ocean Linage (IOL) of CHIKV and represents one of the most emblematic 95 examples of the role of viral glycoproteins in transmission and adaptation (Schuffenecker et 96 al. , 2006). The emergence of the E1-A226V mutation was found to increase transmission by 97 Ae. albopictus mosquitoes conferring a selective advantage over the vector Ae. aegypti 98 (Tsetsarkin et al., 2007; Vazeille et al., 2007). As a consequence, this mutation allowed for 99 rapid spread from the Indian Ocean, to India, Italy and eventually France, due to its ability to 100 infect and to be transmitted by the widespread Ae. albopictus mosquito (Vignuzzi and Higgs, 101 2017). Since then, CHIKV has continued to evolve, accumulating mutations in the viral 102 attachment glycoprotein E2 (e.g., L210Q, K252Q), which further increased CHIKV fitness in 103 Ae. albopictus (Tsetsarkin et al., 2014; Tsetsarkin and Weaver, 2011). This continuous step-104 wise evolution of CHIKV again highlights the viral glycoproteins as key determinants of 105 arbovirus transmission and infectivity. 106In a previous study, we took an in vivo evolution-based approach to study novel and 107 emerging viral determinants of CHIKV transmission and path...

Distinct New York City Aedes albopictus Mosquito Populations Display Differences in Salivary Gland Protein D7 Diversity and Chikungunya Virus Replication

“…Therefore, we were curious whether these populations may harbor genetically unique alleles. We focused on the D7 long form locus due to its known antiviral properties, and therefore functional relevance for viral transmission [ 27 , 28 , 29 , 30 ]. We Sanger-sequenced the D7 long form transcripts from individual mosquitoes from all three populations ( Figure 2 ).…”

“…From those mosquitoes where we successfully amplified the target region, four out of the seven mosquitoes contained variants at sites 80 and 129 of the E1 glycoprotein ( Figure 7 , Table 1 ). These sites are significant because they are linked to phenotypes resulting in increased virulence and transmission for CHIKV [ 30 , 31 ].…”

“…Here, we find the emergence of unique viral variants in saliva after 7 days of replication in NYC mosquitoes ( Figure 7 , Table 1 ). Previous work characterizing adaptive mutations in the E1 glycoprotein has shown that mutations at sites V80 and A129 can result in increased virulence and transmission efficiency in mice [ 30 , 31 ]. These mutations arose during experimental evolution in the laboratory, similar to the setting in which we conducted this study.…”

“…Ae. albopictus mosquitoes from Tallman (F7) were exposed to an artificial blood meal containing 1 × 10 6 CHIKV infectious particles/mL [ 30 ]. Mosquitoes exposed to non-infectious bloodmeals were used as non-infected controls.…”

Clinical manifestations of chikungunya infection in the pediatric population: systematic review

“…The incapacitating nature of the disease has caused a substantial economic burden and collapse in health systems. The local transmission of CHIKV has been reported in more than 100 countries and territories in Asia, Africa, Europe, and the Americas (VILLERO-WOLF Y et al, . NOVAL MG et al, 2019.…”