Sequencing and antigenic studies of a Norwegian virus isolated from encephalomyelitic sheep confirm the existence of louping ill virus outside Great Britain and Ireland

Abstract

We have carried out an antigenic analysis and nucleotide sequence comparison of the envelope glycoprotein of recognized louping ill virus strains isolated from Scotland with that of a Norwegian virus known to cause encephalomyelitis in sheep. Monoclonal antibodies with defined specificity for the louping ill virus envelope glycoprotein failed to distinguish between the Norwegian virus and prototype louping ill virus in indirect immunofluorescence, haemagglutination inhibition and neutralization tests. Nucleotide sequencing of the envelope glycoprotein and alignment of the deduced amino acid sequence with other known sequences revealed that the Norwegian virus closely resembles (> 95 % identity for nucleotide and > 98% identity for amino acid sequences) louping ill virus. Maximum variation in identities among four strains of louping ill virus were 4-4 % and 1.8 % respectively for nucleotide and amino acid alignments. We conclude that sheep encephalomyelitis in Norway is caused by louping ill virus. These results imply that other viruses present in Europe and known to cause encephalitis/encephalomyelitis of sheep could be caused by louping ill virus.Louping ill (LI) virus is a tick-borne member of the genus Flavivirus in the family Flaviviridae and is closely related antigenically to other members of the tick-borne encephalitis (TBE) flavivirus serocomplex (Porterfield, 1980;Westaway et al., 1985;Francki et al., 1991). There are currently about 68 antigenically distinct, but very closely related viruses in the genus, many of which cause serious human and animal diseases. Flaviviruses contain a positive-stranded RNA genome approximately 10.5 kb in length and with a similar organization. Complete or partial nucleotide sequences of many flaviviruses have been determined (Rice et al

Seroprevalence of antibodies to tick-borne encephalitis virus and Anaplasma phagocytophilum in healthy adults from western Norway

“…Traavik and co-workers found evidence of tick-borne encephalitis-like virus in this part of Norway in studies of animals and humans in the 1970s [6][7][8]. However, there is evidence that these findings represented other flaviviruses [9,10]. As far as we know, no recent survey of TBEV in ticks has been performed in Sogn and Fjordane county.…”

Identification of naturally occurring monoclonal antibody escape variants of louping ill virus

“…Viral E gene sequencing of LI/A virus, chosen randomly from the five antibody escape variants, was carried out as described below. A 10 % (w/v) mouse brain suspension of the plaque-purified virus was used for the extraction of viral RNA as previously described (Gao et al, 1993). The virus suspension was treated with proteinase K and extracted with phenol and ether.…”

“…Their geographical origins, the hosts from which they were isolated and the year of isolation are listed in Table 1. Strain L1/31, which is the prototype LI virus, was used for the preparation of monoclonal and polyclonal antibodies, the antigenic specificities of which have been described previously (Venugopal et al, 1992;Gao et al, 1993). Stocks of all viruses were prepared as 10 % (w/v) suspensions of infected suckling mouse brain in PBS pH 7-2.…”

“…So far, no strain diversity has been identified for LI or TBE virus (Heinz & Kunz, 1982;Reid, 1988;Holzmann et al, 1992). It has been reported that the E protein of LI viruses within and outside of the British Isles (Gao et at., 1993) as well as the Japanese isolate of Negishi virus (Venugopal et al, 1992) are closely related as shown by nucleotide sequence and antibody analyses. In this paper, we have extended this work by comparing 18 LI virus isolates obtained in the U.K. and Norway for their reactivities with E-specific and non-structural protein NSl-specific MAbs.…”

Identification and characterization of a novel tick-borne flavivirus subtype in goats (Capra hircus) in Spain

“…Reports of LIV outside the British Isles are rare. A LIV isolate reported from Norway originated from the UK, grouping with the genotype 1 isolates from Scotland & England (Gao et al, 1993a(Gao et al, , 1997. However, LIV also demonstrates a high degree of genetic homology to tick-borne encephalitis virus (TBEV) and other mammalian tick-borne viruses, particularly Spanish sheep encephalitis virus (SSEV).…”