Summary auto-generated
This study examines the molecular characteristics of narcissus latent virus (NLV) and Maclura mosaic virus (MacMV) to clarify their taxonomic classification within the Potyviridae family. Researchers sequenced the 3′-terminal regions of both viruses, including portions of the nuclear inclusion body b (NIb) gene, the complete coat protein gene, and untranslated regions. Biochemical analysis revealed coat protein sizes of 39±5 kDa (NLV) and 40 kDa (MacMV) from infected tissue, though deduced sequences suggested smaller sizes (32±8 and 34±1 kDa respectively). Phylogenetic comparisons showed that NLV and MacMV exhibit closer similarity to bymoviruses than to carlaviruses or other potyviruses, with coat protein identity of only 14-23% to established potyvirus genera—comparable to diversity between recognized potyviruses genera. Both viruses contain a single continuous open reading frame similar to potyviral organization, contrasting with carlavirus genomes. The findings strongly support establishing NLV and MacMV as a new genus, tentatively designated macluraviruses, within the Potyviridae family, rather than classifying them as carlaviruses as previously thought.
Key findings
- NLV and MacMV coat proteins show only 14-23% amino acid identity to established Potyviridae genera, suggesting they constitute a distinct genus rather than belonging to existing classifications
- Sequence analysis reveals NLV and MacMV have closer evolutionary relationships to bymoviruses than to carlaviruses, despite morphological similarities to carlaviruses
- Both viruses contain single continuous open reading frames analogous to potyviral genome organization, unlike the two independent ORFs found in carlavirus genomes
- A proposed LQM cleavage site between NIb and coat protein regions was identified in both viruses, consistent with bymovirus processing patterns
- The authors propose designating NLV and MacMV as a new fifth genus of Potyviridae, tentatively named macluraviruses
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Abstract
The nucleotide sequences of part of the nuclear inclusion body b (NIb) gene, the complete coat protein gene and the 3' untranslated regions of narcissus latent virus (NLV) and Maclura mosaic virus (MacMV) were determined. Deduced amino acid sequences for the NIb and coat protein genes revealed that NLV and MacMV are closely related. Gel analysis and Western blotting of the coat proteins of NLV and MacMV from infected tissue or purified virus indicated that they have molecular masses of 39.5 kDa and 40 kDa (respectively), whereas estimates from deduced amino acid sequences suggested that they have molecular masses of 32.8 kDa and 34.1 kDa. Comparison of the NIb and coat protein sequences with other viruses showed that NLV and MacMV have close affinities with viruses of the Potyviridae and suggests that they should form a new genus of the family.