Research into the bamboo mosaic vi-rus (BaMV) may seem a thankless task, but if the mysteries of this field are plumbed deeply, its unique attributes may be just the key to solving some of the riddles of viruses.
While conducting BaMV research, Lin Na-sheng discovered by happenstance parasitic entities even smaller than a virus: satellite nucleic acids.
Lin notes that satellite nucleic acids require BaMV for replication and envelopment, as well as to move about the body of the host plant. She also discovered that some BaMV satellite nucleic acids interfere with BaMV replication, reducing the damage caused by the virus to plants.
In the past, scientists' understanding of satellite nucleic acids was that they were extensions of the virus genome, given that the virus genome is so small. For example, BaMV has only five genes. Thus the majority of proteins helping it complete its replication cycle are provided by the host plant. Satellite nucleic acids usually serve as "accomplices" that help the virus in attacking its host, compounding symptoms caused by the virus. But satellite nucleic acids isolated from BaMV can, surprisingly, hinder the virus's replication, in turn alleviating symptoms. In this way they become a weapon that helps the host plant defend against the virus. How does this happen? Lin states that traditional medicines cannot treat this viral blight, but satellite nucleic acids, which attach themselves to the virus, can actually obstruct virus replication, providing hope for prevention and treatment of this disease. Although there are still many riddles waiting to be tackled, this new discovery is the focus of Lin's research into treating bamboo.
Furthermore, satellite nucleic acids can serve as a tool for investigating the nucleic acid sequences and gene functions of host viruses.
Having studied the bamboo mosaic virus for nearly 20 years, Lin admits that scientists' knowledge of the virus itself remains quite limited at present. She points out that though BaMV has only five genes, we have only an elementary understanding of the function of these genes. The virus's replication and pathogenic mechanisms are highly involved, plus there's mutual interaction among the genes; therefore, to gain further understanding of the function of each gene, we need another molecule as an intermediary. "Satellite nucleic acids are a vector that could answer this question," says Lin.
By developing BaMV and its satellite nucleic acids into a "two-way vector," one can, for example, destroy one BaMV gene and then use the satellite nucleic acids to introduce a good gene into it, thus facilitating further study of the functioning of the BaMV nucleic acid sequence; this technique was used to understand the core initializing subsequence of the subgenome RNA. This BaMV research model is not only helpful for treating bamboo and pigs; it can also be expanded to other viruses of the same genus, such as potato virus X. The possibilities are endless.
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