Downloaded from www.microbiologyresearch.org by IP: 54.70.40.11 On: Thu, 01 Nov 2018 02:49:56 Short Communication Complete coding sequence and molecular epidemiological analysis of Sindbis virus isolates from mosquitoes and humans, Finland Jussi Sane, 1 Satu Kurkela, 1,2 Niina Putkuri, 1 Eili Huhtamo, 1 Antti Vaheri 1,2 and Olli Vapalahti 1,2,3 Correspondence Jussi Sane jussi.sane@helsinki.fi Received 14 March 2012 Accepted 30 May 2012 1 Infection Biology Research Program, Department of Virology, Haartman Institute, Faculty of Medicine, PO Box 21, FI-00014 University of Helsinki, Helsinki, Finland 2 Department of Virology and Immunology, HUSLAB, PO Box 400, FI-00029 HUS, Helsinki, Finland 3 Department of Veterinary Biosciences, Faculty of Veterinary Medicine, PO Box 66, FI-00014 University of Helsinki, Helsinki, Finland Sindbis virus (SINV) is an arthropod-borne alphavirus, which causes rash-arthritis, particularly in Finland. SINV is transmitted by mosquitoes in Finland but thus far no virus has been isolated from mosquitoes. In this study, we report the isolation of the first SINV strain from mosquitoes in Finland and its full-length protein-coding sequence. We furthermore describe the full-length coding sequence of six SINV strains previously isolated from humans in Finland and from a mosquito in Russia. The strain isolated from mosquitoes (Ilomantsi-2005M) was very closely related to all the other Northern European SINV strains. We found 9 aa positions, of which five in the nsP3 protein C terminus, to be distinctive signatures for the Northern European strains that may be associated with vector or host species adaptation. Phylogenetic analyses further indicate that SINV has a local circulation in endemic regions in Northern Europe and no novel strains are frequently being introduced. Sindbis virus (SINV) is an arthropod-borne, enveloped ssRNA virus in the genus Alphavirus of the family Togaviridae (Powers et al., 2012). The SINV genome is 11.7 kb in size and encodes four non-structural proteins (nsP1–4) and structural proteins (C, E3, E2, 6K and E1) (Strauss et al., 1984; Strauss & Strauss, 1994). SINV is found across Eurasia, Africa and Oceania (Huba ´lek, 2008) and as suggested by a recent study on partial E2 sequences (Lundstro ¨m & Pfeffer, 2010), the virus forms five geno- types with distinct geographical distributions reflecting major bird migration patterns. Clinical SINV infections in humans have been reported primarily from Northern Europe, particularly Finland, where the infection is called Pogosta disease (Kurkela et al., 2004). The infection is known as Ockelbo disease in Sweden (Skogh & Espmark, 1982) and as Karelian fever in Russia (L’vov et al., 1985). Acute SINV infection is characterized by febrile rash- arthritis (Kurkela et al., 2005; Sane et al., 2011; Turunen et al., 1998). SINV infection may also cause persisting joint manifestations (Kurkela et al., 2008a; Laine et al., 2000; Niklasson & Espmark, 1986). Other important pathogenic alphaviruses causing rash-arthritis include Chikungunya and Ross River viruses (Powers et al., 2001). SINV epidemics have emerged approximately every 7 years in Finland with thousands of serologically confirmed cases (Sane et al., 2010). Recent evidence indicates that certain climatic conditions and the density of hatch-year black grouse are significant determinants of the occurrence of human SINV infections in Finland (unpublished data). Mosquitoes have been implicated as the main source of SINV transmission in Finland (Sane et al., 2011), where, however, no virus has previously been isolated from mosquitoes. The late summer mosquito genera, Culex and Culiseta, have been suspected to be potential vectors from which the virus has been isolated in Sweden in the 1980s (Francy et al., 1989; Niklasson et al., 1984). In the present study, we report the isolation of the first SINV strain from mosquitoes in Finland and its full-length protein-coding region sequence. Furthermore, we describe the full-length coding sequence of five SINV strains iso- lated from humans in Finland in 2002 (Kurkela et al., 2004) and of a strain isolated from mosquitoes in Russia in 1983 (L’vov et al., 1985) and the genetic characteristics and evolutionary/phylogenetic relationships of these strains. The GenBank/EMBL/DDBJ accession numbers for the sequences reported in this paper are JQ771793 (Ilomantsi-2005M), JQ771794 (Ilomantsi-2002A), JQ771795 (Ilomantsi-2002B), JQ771796 (Ilomantsi- 2002C), JQ771797 (Johannes-2002), JQ771798 (Kiihtelysvaara-2002) and JQ771799 (LEIV-9298). Supplementary material is available with the online version of this paper. Journal of General Virology (2012), 93, 1984–1990 DOI 10.1099/vir.0.042853-0 1984 042853 G 2012 SGM Printed in Great Britain