Comparative Vector Competence of North American Culex pipiens and Culex quinquefasciatus for African and European Lineage 2 West Nile Viruses

• Published in: The American journal of tropical medicine and hygiene 2018-01, Vol.98 (6), p.1863-1869
• Main Authors: Romo, Hannah, Papa, Anna, Kading, Rebekah, Clark, Rebecca, Delorey, Mark, Brault, Aaron C
• Format: Article
• Language: English
• Subjects: Epidemics; Mosquitoes; West Nile virus
• ISSN: 0002-9637; 1476-1645
• DOI: 10.4269/ajtmh.17-0935

West Nile virus (WNV) is a mosquito-borne flavivirus that is phylogenetically separated into distinct lineages. Lineage 1 (L1) and lineage 2 (L2) encompass all WNV isolates associated with human and veterinary disease cases. Although L1 WNV is globally distributed, including North America, L2 WNV only recently emerged out of sub-Saharan Africa into Europe and Russia. The spread of L2 WNV throughout and beyond Europe depends, in part, on availability of competent vectors. The vector competence of mosquitoes within the genus for WNV is well established for L1 WNV but less extensively studied for L2 WNV. Assessing the vector competence of North American mosquitoes for L2 WNV will be critical for predicting the potential for L2 WNV emergence in North America. We address the vector competence of North American and for L2 WNV. Both mosquito species were highly competent for each of the L2 WNV strains assessed, but variation in infection, dissemination, and transmission was observed. An L2 WNV strain (NS10) isolated during the Greek outbreak in 2010 exhibited a reduced capacity to infect compared with other L2 WNV strains. In addition, a South African L2 WNV strain (SA89) displayed a significantly shorter extrinsic incubation period in compared with other L2 WNV strains. These results demonstrate that North American mosquito species are competent vectors of African and European L2 WNV and that emergence of L2 WNV is unlikely to be hindered by poor competence of North American vectors.