LIU, Jianying et al. Role of mutational reversions and fitness restoration in Zika virus spread to the Americas. Nature Communications, v. 12, n. 595, p. 1-12, 2021.
Artículo
en Inglés
| IED | ID: ied-4236
Zika virus (ZIKV) emerged from obscurity in 2013 to spread from Asia to the South Pacific and the Americas, where millions of people were infected, accompanied by severe disease including microcephaly following congenitalinfections. Phylogenetic studies have shown that ZIKV evolved in Africa and later spread to Asia, and that the Asian lineage is responsible for the recent epidemics in the South Pacific and Americas. However, the reasons for the sudden emergence of ZIKV remain enigmatic. Here we report evolutionary analyses that revealed four mutations, which occurred just before ZIKV introduction to the Americas, represent direct reversions of previous mutations that accompanied earlier spread from Africa to Asia and early circulation there. Our experimental infections of Aedes aegyptimosquitoes, humancells, and mice using ZIKVstrains with and without these mutations demonstrate that the original mutations reduced fitness for urban, human-amplifed transmission, while the reversions restored fitness, increasing epidemicrisk. These findings include characterization of three transmission-adaptive ZIKVmutations, and demonstration that these and one identified previously restored fitness for epidemictransmission soon before introduction into the Americas. The initial mutations may have followed founder effects and/or drift when the virus was introduced decades ago into Asia.