Isolation and characterization of a California encephalitis serogroup orthobunyavirus from Finnish mosquitoes.
The mosquito-borne California encephalitis serogroup viruses of the genus Orthobunyavirus (family Bunyaviridae) include several causative agents of encephalitis in humans. Until recently, Inkoo virus (INKV) was the only orthobunyavirus isolated in Finland, showing high seroprevalence in the population. In this study, we recovered five orthobunyavirus isolates from mosquitoes collected in eastern Finland in the early autumns of 2007 and 2008 by inoculation of Vero cells. The isolates were determined by S, M and L segment sequences to represent the California encephalitis virus species but distinct from INKV (68% polyprotein amino acid (aa) identity). In genetic analyses, isolates clustered together with a number of westernmost Chatanga virus isolates (98% polyprotein aa identity) reported from Russia, forming a distinct phylogroup. However, the sequence homology of this phylogroup to the majority of Chatanga isolates, comprising three different geographically clustered phylogroups, was considerably lower (89-92% polyprotein aa identity). The five new isolates were designated as Möhkö isolates of Chatanga virus, according to the village of origin. The isolates were closely related to Snowshoe hare virus (SSHV) and La Crosse virus (LACV) with an aa identity of 87% and 82% within the M segment polyprotein, respectively. The genetic relatedness of Möhkö isolates to a number of human pathogenic orthobunyaviruses warrants further investigation on their potential disease associations and further serological analysis is needed to compare them to other Chatanga virus isolates and SSHV to determine their true antigenic relation.
Haartman Institute, Department of Virology, Faculty of Medicine, University of Helsinki, Finland. Electronic address: niina.putkuri@helsinki.fi.
Niina
N
Putkuri
Haartman Institute, Department of Virology, Faculty of Medicine, University of Helsinki, Finland; HUSLAB, Helsinki University Central Hospital, Helsinki, Finland.
Satu
S
Kurkela
Haartman Institute, Department of Virology, Faculty of Medicine, University of Helsinki, Finland.
Lev
L
Levanov
Haartman Institute, Department of Virology, Faculty of Medicine, University of Helsinki, Finland.
Eili
E
Huhtamo
Haartman Institute, Department of Virology, Faculty of Medicine, University of Helsinki, Finland; HUSLAB, Helsinki University Central Hospital, Helsinki, Finland.
Antti
A
Vaheri
Haartman Institute, Department of Virology, Faculty of Medicine, University of Helsinki, Finland.
Tarja
T
Sironen
Haartman Institute, Department of Virology, Faculty of Medicine, University of Helsinki, Finland; HUSLAB, Helsinki University Central Hospital, Helsinki, Finland; Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Finland.
Olli
O
Vapalahti
D000818:Animals; D002522:Chlorocebus aethiops; D009033:Culicidae / Q000821:virology*; D004670:Encephalitis, California / Q000821:virology*; D005387:Finland; D016851:Orthobunyavirus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D010802:Phylogeny; D014709:Vero Cells
California serogroup virus; Chatanga virus isolate; Mosquito-borne virus; Orthobunyavirus; Snowshoe hare virus-like