Perspectives of molecular barcoding for virus research
Undoubtedly, molecular barcodes should strengthen their power in the context of molecule quantification. Together with precise instruments, such as the microfluidic system to delicately detect individual molecules and deep learning algorithms, dedicated to accurately interpret, calculate and classify each sequence of barcodes, we can foresee that molecular barcodes will continue to be one of the most attractive methods applied for quantitative biology. Additional advantage of the molecular barcoding approach is that we will be able to track any intermediate product relevant to the origin of genomic DNA, such as RNA isoforms and antisense RNA or the functional unit which is absent following mRNA processing; few examples have already shown the feasibility of molecular barcoding for tackling these questions[28,158,159]. Furthermore, no matter barcoding DNA- or RNA viruses, molecular barcodes are presently embedded in genomic DNA or cDNA. However welcome, it is known that many zoonotic viruses causing EIDs belong to RNA viruses. Direct barcoding and sequencing native viral RNA molecules without conversion to cDNA will be expected to bring us a more informative picture concerning chemical RNA modifications present in the native RNA molecules and the whole transcriptome. Example given by Smith and colleagues[160]demonstrated the potential for barcoding directly on native RNA molecules by using the platform offered by Oxford Nanopore Technologies.