This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A research team led by distinguished professor Giuseppe Pezzotti at the Biomedical Engineering Center, Kansai Medical University (Japan), has demonstrated that differences in the molecular structures of viral RNA can be captured as "Raman barcodes," enabling the identification of 20 SARS-CoV-2 variants and subvariants. These findings are expected to contribute to the development of a rapid method for identifying newly emerging viral variants.
The findings were published online in the journal Advanced Science on Sept. 30, 2026. The identification and surveillance of viral variants have traditionally relied on RNA sequencing, which provides detailed information about the nucleotide sequence of a virus but requires lengthy procedures using specialized instrumentation, sample processing and computational analysis. However, viral RNA is more than a simple sequence of the four genetic bases.
RNA molecules fold into complex three-dimensional structures through interactions between neighboring nucleotides and complementary bases. These secondary structures can influence how RNA behaves biologically and can differ even when the overall nucleotide composition appears similar. Raman spectroscopy is capable of instantaneously reading such structures.
The researchers therefore asked a fundamental question: Can the molecular vibrations of viral RNA provide a distinctive fingerprint of different viral variants, even when their conventional genetic composition appears highly similar? Raman spectroscopy offers a direct way to probe molecular vibrations. Instead of reading the RNA sequence letter by letter, it captures a molecular vibrational fingerprint arising from the RNA backbone, ribose rings, phosphate linkages and nitrogenous bases.
The study introduces the concept of encoding these fingerprints as Raman barcodes, providing the basis for a new concept of a "Raman genome." RNA nucleotide strands were extracted from 20 SARS-CoV-2 strains, comprising the original Japanese isolate, alpha, beta, gamma, delta, lambda, theta, mu and 12 omicron subvariants. The Raman spectra of these RNAs were systematically acquired and mathematically deconvoluted to identify their individual molecular components. Although all samples shared characteristic signals associated with the RNA backbone, ribofuranose rings, phosphate groups and nitrogenous bases, subtle but reproducible differences emerged among the strains.
These differences were not simply a reflection of differences in the relative abundance of the four RNA bases. The investigated strains showed highly similar base fractions when evaluated from their genome sequences, yet their Raman spectra exhibited markedly different molecular signatures. The researchers therefore encoded the characteristic spectral features into Raman barcodes.
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