Emergence and Spreading Potential of Zika Virus

Abstract

Zika virus (ZIKV) is an arthropod-borne Flavivirus (family Flaviviridae) closely related to dengue, yellow fever and West Nile viruses. ZIKV remained neglected, confined to enzootic transmission cycles in Africa and Asia, until the first significant outbreak was reported in Micronesia in 2007. Subsequent epidemics of growing incidence occurred in French Polynesia and other South Pacific Islands, and recently, in the Americas. The latter and currently ongoing outbreak of unprecedented incidence revealed the association of ZIKV infection with the occurrence of severe congenital malformations and neurological diseases, leading to a widespread concern about its potential to pose a global public health threat. Serological and molecular data suggest that the genetic and geographic diversification of ZIKV may be greatly underestimated. Here we discuss several ecological and epidemiological aspects, together with the evolutionary processes that may have driven the emergence and abrupt spread of ZIKV in the Americas.

Keywords: ZIKV; emerging infectious diseases; genetic variability ZIKV; molecular evolution; spreading potential ZIKV.

FIGURE 1

Maximum-likelihood analysis of all complete ORF sequences of Zika virus (ZIKV) available. The phylogenetic tree was performed using PhyML software (Guindon et al., 2005) under a GTR+G+I substitution model, and edited with FigTree program v1.4.2 (available at: http://tree.bio.ed.ac.uk). Strains are indicated by their accession number, year and country of isolation. Sequences derived from variants isolated during current American outbreak and from imported strains from Fiji and Samoa (Deng et al., 2016; Zhang et al., 2016), are indicated in blue and red, respectively. Bootstrap values >90% support major nodes but are not shown for visualization purpose. The bar at the bottom of the tree denotes nucleotide distance.