Role of Anopheles Mosquitoes in Cache Valley Virus Lineage Displacement, New York, USA.

Constentin Dieme,Alexander T Ciota,Joseph G Maffei,Lili Kuo,Chelsea Shultis,Kiet A Ngo,Steven D Zink,Michael A Drebot,Alan P Dupuis,Anne F Payne,Shaun Tyler,Laura D Kramer,P Bryon Backenson,Cheri A Koetzner,Jessica Stout

doi:10.3201/eid2802.203810

Abstract

Cache Valley virus (CVV) is a mosquitoborne virus that infects livestock and humans. We report results of surveillance for CVV in New York, USA, during 2000–2016; full-genome analysis of selected CVV isolates from sheep, horse, humans, and mosquitoes from New York and Canada; and phenotypic characterization of selected strains. We calculated infection rates by using the maximum-likelihood estimation method by year, region, month, and mosquito species. The highest maximum-likelihood estimations were for Anopheles spp. mosquitoes. Our phylogenetic analysis identified 2 lineages and found evidence of segment reassortment. Furthermore, our data suggest displacement of CVV lineage 1 by lineage 2 in New York and Canada. Finally, we showed increased vector competence of An. quadrimaculatus mosquitoes for lineage 2 strains of CVV compared with lineage 1 strains.

Highlights

Cache Valley virus (CVV) is a mosquitoborne virus that infects livestock and humans
Consistent with the findings of Armstrong et al, who analyzed CVV strains from Connecticut [4], we identified substantial variability in CVV activity in New York during 2000–2016
In both states, CVV could be isolated from different mosquito genera, including Aedes, Anopheles, and Coquillettidia [6]

Summary

Introduction

We report results of surveillance for CVV in New York, USA, during 2000–2016; full-genome analysis of selected CVV isolates from sheep, horse, humans, and mosquitoes from New York and Canada; and phenotypic characterization of selected strains. Our data suggest displacement of CVV lineage 1 by lineage 2 in New York and Canada. We showed increased vector competence of An. quadrimaculatus mosquitoes for lineage 2 strains of CVV compared with lineage 1 strains. Lineage 1 viruses were isolated in the United States and Canada during 1956–2011, and lineage 2 consists of more recent strains from the northeastern United States [4]. Accumulating evidence from surveillance suggests that Anopheles quadrimaculatus and An. punctipennis mosquitoes might be major vectors of CVV [6]. We determined vector competence of An. quadrimaculatus for representative CVV strains

Methods

Results

Conclusion