genome of Beet cryptic virus 1 shows high homology to certain cryptoviruses present in phylogenetically distant hosts

• Published in: Virus genes Vol. 40; no. 2; pp. 267 - 276
• Main Authors: Szegő, Anita, Enünlü, Natalya, Deshmukh, Sachin D, Veliceasa, Dorina, Hunyadi-Gulyás, Éva, Kühne, Thomas, Ilyés, Pál, Potyondi, László, Medzihradszky, Katalin, Lukács, Noémi
• Format: Journal Article
• Language: English
• Published: Boston Boston : Springer US 01.04.2010; Springer US; Springer Nature B.V
• Subjects: 3' Untranslated Regions; 5' Untranslated Regions; Amino Acid Sequence; Beet cryptic virus 1; Beta vulgaris - virology; Biomedical and Life Sciences; Biomedicine; Capsid Proteins - genetics; Cluster Analysis; Daucus; Genome, Viral; Medical Microbiology; Molecular Sequence Data; Phylogeny; Plant Sciences; Plant Viruses - classification; Plant Viruses - genetics; Plant Viruses - isolation & purification; Protein Structure, Secondary; RNA Replicase - genetics; RNA Viruses - classification; RNA Viruses - genetics; RNA Viruses - isolation & purification; RNA, Viral - genetics; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Sequence Homology, Nucleic Acid; Vicia cryptic virus; Virology; White clover cryptic virus 1; Virus genome; Horizontal transfer; Sugar beet; BCV
• ISSN: 0920-8569; 1572-994X
• DOI: 10.1007/s11262-009-0432-4

This study determined the complete nucleotide sequence of Beet cryptic virus 1 (BCV1). As expected by analogy to previously sequenced alphacryptoviruses, dsRNA1 (2008 bp) encodes a 72.5-kDa protein containing sequence motifs characteristic for RNA-dependent RNA polymerases (RdRp). In addition to the full-length dsRNA1, a truncated form was also detected in dsRNA extracts. dsRNA2 (1783 bp) codes for the viral coat protein (CP) as proven by the identity of the predicted CP sequence to peptide sequences of the purified virion protein. The amino acid sequence of BCV1 RdRp as well as the 5′- and 3′-UTRs show 81-85% identity to the corresponding regions of Vicia cryptic virus (VCV), White clover cryptic virus 1 (WCCV1) and Carrot cryptic virus (CaCV). The amino acid sequence identity of the CP is about 55-62%, moreover, a strong conservation of predicted α-helical regions was observed. The high degree of similarity of these seed- and pollen-transmitted viruses persisting in phylogenetically distant hosts, together with their high similarity to fungal partitiviruses strongly supports the hypothesis that horizontal transfer by a fungus played a role in the emergence of the present cryptovirus species. The change in the distribution of cryptic viruses may also be due to human influence: While earlier BCV1 occurred frequently in sugar beet cultivars, it is very rare in cultivars currently used in agricultural practice and was detected in only one of the 28 cultivars investigated in our experiments.