Genetic characterization of the Wyeomyia group of orthobunyaviruses and their phylogenetic relationships

Abstract

Phylogenetic analyses can give new insights into the evolutionary history of viruses, especially of viruses with segmented genomes. However, sequence information for many viral families or genera is still limited and phylogenies based on single or short genome fragments can be misleading. We report the first genetic analysis of all three genome segments of Wyeomyia group viruses Wyeomyia, Taiassui, Macaua, Sororoca, Anhembi and Cachoeira Porteira (BeAr328208) in the genus Orthobunyavirus of the family Bunyaviridae. In addition, Tucunduba and Iaco viruses were identified as members of the Wyeomyia group. Features of Wyeomyia group members that distinguish them from other viruses in the Bunyamwera serogroup and from other orthobunyaviruses, including truncated NSs sequences that may not counteract the host's interferon response, were characterized. Our findings also suggest genome reassortment within the Wyeomyia group, identifying Macaua and Tucunduba viruses as M-segment reassortants that, in the case of Tucunduba virus, may have altered pathogenicity, stressing the need for whole-genome sequence information to facilitate characterization of orthobunyaviruses and their phylogenetic relationships.

Fig. 1.

Analysis of Wyeomyia group M- and L-segment ORFs. (a) Deduced M-segment polyprotein sequences of Wyeomyia group viruses were analysed for predicted processing sites for the generation of mature proteins Gn, NSm and Gc. In addition to the conserved protease motif (protease site) and trypsin-like site (trypsin), potential signal-peptide cleavage sites were analysed using algorithms implemented in Geneious and SignalP-NN/SignalP-HMM; three sites were predicted (signal 1, 2 and 3). Different signal 2 sites out of the two highest-scoring motifs (AT/SA-E/DE or T/SL/IC-V/IA/V) were favoured for different viruses by the algorithms. (b) Deduced M-segment polyprotein sequences of Wyeomyia group viruses were analysed for predicted N-glycosylation sites. The likelihood of glycosylation at a given site is indicated by the height of the line in the diagram. (c) RNA-dependent RNA polymerase motifs pre-A, A, B, C, D and E were identified in the deduced L-segment amino acid sequence of Wyeomyia group viruses.

Fig. 2.

Phylogenetic relationships of Wyeomyia group viruses amongst themselves and to other representative orthobunyaviruses. Deduced amino acid sequences of the S (N ORF) (a), M (Gn, NSm, GC polyprotein ORF) (b) and L (POL ORF) (c) segments of Wyeomyia group viruses were aligned with those of representative orthobunyaviruses, and phylogenetic trees were reconstructed with the maximum-likelihood method as implemented in mega5, performing 1000 pseudoreplicates. The resulting bootstrap values are indicated at the respective nodes. Bars, 0.1 substitutions per site (a, b); 0.05 substitutions per site (c). GenBank accession numbers are given next to virus abbreviations: MAGV, Maguari virus; MDV, Main Drain virus; NORV, Northway virus; POTV, Potosi virus; CVV, Cache Valley virus; TENV, Tensaw virus; FSV, Fort Sherman virus; BATV, Batai virus; SHOV, Shokwe virus; BIRV, Birao virus; NOLAV, Nola virus; ILEV, Ilesha virus; MBOV, Mboke virus; BOZOV, Bozo virus; BUNV, Bunyamwera virus; NRIV, Ngari virus; MPOV, M’Poko virus; GERV, Germiston virus; KRIV, Kairi virus; GROV, Guaroa virus; BWAV, Bwamba virus; PGAV, Pongola virus; TVTV, Trivittatus virus; CHTV, Chatanga virus; SSHV, snowshoe hare virus; LACV, La Crosse virus; TAHV, Tahyna virus; CEV, California encephalitis virus; SAV, San Angelo virus; MELV, Melao virus; SOURV, South River virus; JCV, Jamestown Canyon virus; JSV, Jerry Slough virus; CARV, Caraparu virus; VINV, Vinces virus; ORIV, Oriboca virus; MTBV, Marituba virus; MADV, Madrid virus; LEAV, Leanyer virus; OROV, Oropouche virus; AKAV, Akabane virus. GenBank accession AJ697960 is reported as representing members of an uncharacterized orthobunyavirus group from Peru (Mores et al., 2009), possibly related to TUCV when comparing the reported partial Gn sequence to the sequences presented in this paper.