Putative Lineage of Novel African Usutu Virus, Central Europe

[Sarah Gregory] The authors characterize the complete genome of the putative novel Usutu virus strain Usutu-BONN detected in a dead black bird from Germany. Genomic analysis revealed several unique amino acid substitutions among the polyprotein gene. Phylogenetic analysis demonstrated that Usutu bond constitutes a putative novel African Usutu virus lineage, which was probably, recently, introduced to Central Europe. Originally isolated from a Culex neavei mosquito in South Africa in 1959, Usutu virus was subsequently detected in different mosquito and bird species throughout sub-Saharan countries. Usutu virus has recently been introduced to Europe, where it caused wide spread deaths among resident bird populations, established a local transmission cycle, and became a resident pathogen. Usutu virus is maintained in an enzootic cycle involving mosquitos as vectors and birds as the main amplifying hosts. Humans are considered incidental or dead-end hosts. The authors have demonstrated that bats could also be infected with Usutu virus and might act as amplifying hosts, and there is increasing evidence that Usutu virus is pathogenic for humans, thus becoming a potential public health problem. On the basis of genetic differences, in comparison with Usutu virus strains from Africa, the Usutu virus strain from Europe, except those from Spain, form a distinct clade within Usutu virus phylogeny. The detection and isolation of Usutu virus from different bird species and mammalophilic mosquitos during the 2011 epizootic in Germany raised questions regarding the Usutu virus host range. Thus, as a part of the German Arbovirus Surveillance Program, the authors continued the monitoring of the mosquitoes, birds, and bats for the presence of Usutu virus.