Molecular characterization of a proposed novel macluravirus identified in sand ginger (Kaempferia galanga)

A novel macluravirus, designated provisionally as "kaempferia virus A" (KVA), was identified in sand ginger (Kaempferia galanga) by reverse transcription polymerase chain reaction (RT-PCR). The complete genome of this virus is 8,274 nucleotides in length, excluding the poly(A) tail. Its genome organization is typical of members of the genus Macluravirus, with a single large open reading frame (ORF) that encodes a polyprotein of 2,636 amino acids that is predicted to be processed into nine mature proteins. Comparative sequence analysis revealed that KVA shares 55-70% nucleotide sequence identity across the genome, as well as 49-77% and 42-68% amino acid sequence identity in the polyprotein and coat protein (CP), respectively, with the other reported macluraviruses. Phylogenetic analysis based on nucleotide sequences of the ORF showed that KVA was most closely related to and placed in the same clade with members of genus Macluravirus. The results indicate that KVA represents a new species of the genus Macluravirus in the family Potyviridae. To our knowledge, this is the first report of a plant virus infecting Kaempferia species.