New light-based tool could cut cost of spotting viral infections

Sub: Science and tech

Sec: Space sector

Tags: Venus

Context:

Recently, researchers from Harvard University, Cambridge, and Jiangsu University, Zhenjiang, reported developing one such tool which can detect if cells have been infected by a virus using only light and some knowledge of high-school physics.

Viral infections:

A virus’ spread from animals to humans could unleash pandemics like COVID-19 creating significant public health crises with considerable economic and social fallout.
To nip such infections in the bud, public health researchers have advocated the ‘One Health’ approach:
- monitoring and protecting plants, animals, environment, and human health in an integrated fashion.
The one going on around the world killed more than 131 million poultry in 81 countries in 2022 and 2023, according to the World Health Organisation.
The methods they use include polymerase chain reaction or antigen tests, which detect the genes or proteins associated with the H5N1 virus.

Methodology of the light based tool:

A viral infection can stress cells and change their shapes, sizes, and features.
The researchers behind the new study translated the cellular changes into patterns that could be used to say if a cell had been infected. They infected cells from a pig’s testicles with pseudorabies virus, shone light on them through a microscope, and tracked how changes in the cells distorted the light.
Then they compared these distortions with those in light that had been shone through healthy cells. They finally reported that the difference between the two light patterns represented a ‘fingerprint’ of virus-infected cells.

Diffraction:

Diffraction is the interference or bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture.
Diffraction is the tendency of light waves to spread out after they pass through narrow openings or around small objects.
Once this diffracted light reaches a wall it renders a pattern of alternating light and dark rings or stripes around a dark center.
The fingerprint was based on two parameters:
- the contrast between the light and dark stripes and
- the inverse differential moment, a mathematical value that defined how textured the diffraction pattern was.
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.

Other methods used to detect viruses:

In one technique, researchers isolate infected cells in the lab and add chemical reagents like dimethyl thiazolyl diphenyl tetrazolium bromide to them.
The reagent destroys the cells, but not before the enzymes in the cells (called oxidoreductases and dehydrogenases) react with the reagent to produce purple crystals of a chemical entity called formazan.
This color change tells researchers the cells could have had a viral infection.
Cells dying of a viral infection lack these enzymes and thus produce little to no amounts of formazan crystals.

Advantages of Light Based methods:

The researchers compared their new technique with this standard for accuracy, time, and cost.
The light-based method could detect viral infections as accurately or even more accurately than the standard method.
The new method was also cheaper than the standard: while the equipment cost for the standard method using chemical reagents is about $3,000 (Rs 2.5 lakh), the cost of the new method described in this paper was about a tenth.
The new method reportedly takes only about two hours to detect virus infected cells, against the 40 hours the current standard required.
The low cost and ease of use point are likely to be lucrative to people working closely with animals, especially livestock or common pets such as dogs and cats.
The new tool can help spot viral infections in their bodies as well as for the selection and breeding of excellent livestock and poultry species at the cellular level.
While the new method is not specific to certain kinds of viruses, it can help detect viral infections in general and help stakeholders take preventive measures in time to avoid significant losses.