Molecular epidemiology of bluetongue virus serotype 4 isolated in the Mediterranean Basin between 1979 and 2004
VIRUS RESEARCH
Authors: Breard, Emmanuel; Sailleau, Corinne; Nomikou, Kyriaki; Hamblin, Chris; Mertens, Peter P. C.; Mellor, Philip S.; El Harrak, Medhi; Zientara, Stephan
Abstract
The nucleotide sequences of genome segments 2, 7, 8, 9 and 10, coding for viral proteins (VP) and non-structural proteins (NS)-VP2, VP7, NS2, VP6 and NS3/NS3A, respectively, were determined and compared for 10 strains of bluetongue virus (BTV) serotype 4 isolated in the Mediterranean Basin between 1979 and 2004, and the South African attenuated BTV 4 vaccine strain. The sequence data generated for the BTV 4 strains isolated in Greece in 1979, 1999 and 2000 showed that they had a common origin but were distinct from the lineage of the BTV 4 strains isolated from 2003 onward in the western Mediterranean Basin (Italy, Morocco, Spain and Corsica). The nucleotide and deduced amino acid (aa) sequences of the BTV 4 strains within each lineage were identical to each other, irrespective of the year of isolation or the geographical location. Although the sequence of VP2 from the Turkish and Greek strains were highly similar, there were sufficient differences in the VP6, VP7 and NS2 proteins to suggest that the Turkish BTV 4 belongs to a third lineage. Alignment of the NS3 sequences from the attenuated BTV 4 vaccine strain and the field strains showed 13 aa substitutions, which may, either singularly or together, be responsible for attenuation and hence determining the virulence of the virus. (c) 2007 Elsevier B.V. All rights reserved.
HETEROGENEITY OF THE AMINO-ACID-SEQUENCES OF ESCHERICHIA-COLI SHIGA-LIKE TOXIN TYPE-I OPERONS
GENE
Authors: PATON, AW; BEUTIN, L; PATON, JC
Abstract
PCR was used to amplify approx. 1470-bp segments of DNA containing complete Shiga-like toxin type I(sltI) operons from Escherichia coli strains belonging to serotypes O48:H21, O111:H- and OX3:Hs. These fragments were cloned and DNA sequence analysis identified several variations, as compared with published sltI sequences. All three sltI genes analysed were more closely related to Shiga toxin-encoding genes (sht) of Shigella dysenteriae type 1, than to previously published E. coli phage-encoded sltI genes. The greatest deviation in deduced amino acid (aa) sequence was observed in the SltI protein from the OX3:H8 strain, which differed from the phage 933J-encoded SltI by 9 aa in the A subunit and 3 aa in the B subunit.