VIRUS (Syllabus: GS Paper 3 – Sci and Tech)

News-CRUX-10     30th May 2024        
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Context: Recently, researchers from Harvard University, Cambridge, and Jiangsu University, Zhenjiang, reported developing one such tool: it can detect if cells have been infected by a virus using only light and some knowledge of high-school physics.


  • About: Virus are infectious agent of small size and simple composition that can multiply only in living cells of animals, plants, or bacteria.

oThe name is from a Latin word meaning “slimy liquid” or “poison.”

  • Discovery: By Russian scientist Dmitry I. Ivanovsky in 1892.
  • Taxonomic Position: Viruses occupy a unique taxonomic position, distinct from plants, animals, and prokaryotic bacteria, often placed in their own kingdom.
  • Composition: All true viruses contain nucleic acid (DNA or RNA) and protein, with the nucleic acid encoding the genetic information unique to each virus.
  • Parasitic Nature:

o Viruses are obligate parasites, dependent on host cells for replication and almost all life-sustaining functions.

o Lack of ribosomes prohibits protein synthesis, necessitating the use of host cell ribosomes for viral mRNA translation.

  • Viral Infection: It can stress cells and change their shapes, sizes, and features. As the infection gains the upper hand and the body becomes ‘diseased’, the changes become more stark.
  • Parameters of the Fingerprint: The contrast between the light and dark stripes and the inverse differential moment, a mathematical value that defined how textured the diffraction pattern was.
  • Differentiation of Cell States: The method can differentiate between uninfected, virus-infected, and dead cells. 
  • Virus-infected cells were elongated and had more clear boundaries than uninfected cells. This changed the contrast between light and dark stripes of the diffraction fingerprint, and increased the differences in light intensity.
  • Comparison with Standard Techniques: The researchers compared their new technique with this standard for accuracy, time, and cost. 
  • They reported that their light-based method could detect viral infections as accurately or even more accurately than the standard method.
  • Current methods to detect virus infections in cells are not straightforward.
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