Transmission Incompetence of Culex quinquefasciatus and Culex pipiens pipiens from North America for Zika Virus

Abstract

AbstractIn late 2014, Zika virus (ZIKV; <i>Flaviviridae</i>, <i>Flavivirus</i>) emerged as a significant arboviral disease threat in the Western hemisphere. <i>Aedes aegypti</i> and <i>Aedes albopictus</i> have been considered the principal vectors of ZIKV in the New World due to viral isolation frequency and vector competence assessments. Limited reports of <i>Culex</i> transmission potential have highlighted the need for additional vector competence assessments of North American <i>Culex</i> species. Accordingly, North American <i>Culex pipiens</i> and <i>Culex quinquefasciatus</i> were orally exposed and intrathoracically inoculated with the African prototype ZIKV strain and currently circulating Asian lineage ZIKV strains to assess infection, dissemination, and transmission potential. Results indicated that these two North American <i>Culex</i> mosquito species were highly refractory to oral infection with no dissemination or transmission observed with any ZIKV strains assessed. Furthermore, both <i>Culex</i> mosquito species intrathoracically inoculated with either Asian or African lineage ZIKVs failed to expectorate virus in saliva. These in vivo results were further supported by the observation that multiple mosquito cell lines of <i>Culex</i> species origin demonstrated significant growth restriction of ZIKV strains compared with <i>Aedes</i>-derived cell lines. In summation, no evidence for the potential of <i>Cx. pipiens</i> or <i>Cx. quinquefasciatus</i> to serve as a competent vector for ZIKV transmission in North America was observed.