Arthropod-borne Viruses in Danube Delta: Surveillance, Phylogeography and Vector Feeding Patterns

Abstract

Table of Contents Abstract ....................................................................................................................................... 1 Zusammenfassung.................................................................................................................... 4 Acknowledgements.................................................................................................................. 7 List of Abbreviations ............................................................................................................. 10 List of Figures .......................................................................................................................... 14 List of Tables ........................................................................................................................... 18 1 Introduction .......................................................................................................................... 19 1.1 Background ........................................................................................................................ 19 1.2 Arbovirus surveillance in Europe ................................................................................. 26 1.2.1 Arbovirus surveillance in Romania..................................................................................... 28 1.3 Arboviruses relevant to public health in Europe ....................................................... 30 1.3.1 Mosquito-borne viruses ......................................................................................................... 30 1.3.2 Tick-borne viruses .................................................................................................................. 34 1.3.3 Culicoides-borne viruses ........................................................................................................ 37 1.4 The importance of vector feeding patterns.................................................................. 39 1.4.1 Xenosurveillance: disease identification using blood meals ......................................... 41 1.5 Study rationale and aims................................................................................................. 42 1.6 List of publications........................................................................................................... 45 2 Additional Chapter: Discovery and Genetic Characterization of Sulina Virus, a Novel Orthonairovirus Infecting Ixodes ricinus Ticks from Danube Delta ............... 47 2.1 Background ........................................................................................................................ 47 2.2 Materials and methods .................................................................................................... 49 2.2.1 Tick sampling and processing .............................................................................................. 49 2.2.2 Sulina virus discovery and genome sequencing............................................................... 49 2.2.3 Prevalence of Sulina virus in ticks ...................................................................................... 50 2.2.4 Virus isolation.......................................................................................................................... 50 2.2.5 Serological screening of engorged ticks and host sera .................................................... 51 2.2.6 Sequence data analysis........................................................................................................... 51 2.3 Results................................................................................................................................. 53 2.3.1 Tick identification, molecular and serological screening of Sulina virus ................... 53 2.3.2 Sulina virus genome ............................................................................................................... 54 2.3.3 Phylogenetic analysis ............................................................................................................. 60 2.4 Discussion .......................................................................................................................... 63 3 General Discussion ............................................................................................................. 69 3.1 Vector surveillance in Danube Delta Biosphere Reserve......................................... 69 3.1.1 Longitudinal mosquito surveillance ................................................................................... 69 8 3.1.2 Species composition of Culicoides biting midges ............................................................ 76 3.2 Detection and characterization of arboviruses ........................................................... 81 3.2.1 West Nile virus: phylogeography of an endemic pathogen ........................................... 81 3.2.2 Letea virus: a reassortant orbivirus discovered in grass snakes (Natrix natrix) ......... 87 3.3 Vectors feeding patterns.................................................................................................. 94 3.3.1 Host-feeding pattern of mosquitoes.................................................................................... 94 3.3.1.1 Xenosurveillance of WNV using mosquito blood meals ........................................... 100 3.3.2 Blood meal analysis of Culicoides biting midges ........................................................... 102 4 Conclusions and outlook ................................................................................................. 107 5 References ........................................................................................................................... 110 Appendix ................................................................................................................................ 142