Researchers at Harvard University and Jiangsu University developed a technique for not only identifying infected cells, but also tracking the infection over time as the cells developed. They published their study, “Virus detection light diffraction fingerprints for biological applications,” in Science Advances.

“Viruses, infections, and pandemics have become recurrent features in our lives, profoundly impacting human existence and even extending their reach to animals. Despite this, accessible, rapid, and affordable virus detection methods have been lacking,” said Xingcai Zhang, PhD, researcher, Harvard University, told GEN. “Our study aims to visualize viral infection states, predict infection duration, unravel the infection process, explore inhibition methods, and contribute to understanding viral disease transmission and pathogenesis.”

Viral infection of cells causes stress resulting in cell morphology differences over time. This study leveraged those known morphological changes to discern between infected and non-infected cells in culture. The standard practice for identifying infected cells, the methyl thiazolyl tetrazolium (MTT) assay, requires the use of reagent treatments and chemical reactions which can take upwards of 40 hours per sample, which is destroyed in the process.

The method proposed in this paper uses a lensless light diffraction platform to detect diffraction patterns, which can be used to extract information such as contrast and inverse differential moment which are used to create diffraction fingerprints. The fingerprints can be monitored continuously in the same samples as there is no inherent damage to cells.

“Conventional detection methods introduce various variables to the viral infection process, confounding accuracy. Non-destructive testing isolates the virus as a singular factor, yielding more precise results,” Zhang told GEN. “Our light diffraction spectroscopy method preserves cell integrity during detection, ensuring that results reflect the inherent characteristics of the target, unaffected by external conditions. Spectroscopy, being non-contact and non-destructive, directly observes viral infection dynamics through cell morphological changes in the diffraction fingerprint profile, without compromising the sample.”

Highly accurate method

Not only does this lensless light diffraction method enable the continuous monitoring of infection progression, but it is also a highly accurate method when compared to MTT. Researchers treated Swine testicle cell lines with Pseudorabies virus. Infected and non-infected cells were evaluated using both methods. The results were significantly correlated, showing the diffraction method having a 98.9% correlation to the MTT method results. The diffraction method can be automated, and the procedure utilizes low lost materials and samples can be analyzed within two hours, compared to high cost equipment and materials costs and 40-hour analysis time.

“This paper provides an innovative detection method that eliminates the need for professional personnel and expensive complex professional field detection equipment for the prevention of viral infectious diseases and the study of cytovirology. Our continuous and high-throughput cell-based virus fingerprint research can be applied for the detection of viral diseases in humans, pets and livestock, and the selection and breeding of excellent livestock and poultry species at the cellular level. On the other hand, it can also detect the hidden spread of human-to-human, animal-to-animal, and zoonotic diseases in time and inhibit and block their further development,” wrote the authors.

Researchers hope that this method can be further refined for more broadscale use to address a wide range of concerns from detecting illness in humans, pets, and other animals, to studying human-to-human transmission of illnesses, to facilitating selective breeding in livestock. “This approach not only offers detection solutions but also contributes to curtailing the spread and impact of viral diseases in various domains, including veterinary science, pandemic preparedness, and drug screening,” said Zhang.

The next steps include integrating “insights from genomics, proteomics, and cytology will enhance the accuracy of our models” with the goal of revealing the relationships between these fields and diffraction, he continued. Ultimately, the researchers’ goals include introducing the diffraction methodology into industry settings.

“Further refinements in virus disease detection will underpin early biological screening, pandemic forecasting, veterinary practice, and drug development. This advancement holds promise for preemptive action against viral outbreaks, safeguarding human and animal well-being, either independently or in synergy with other cutting-edge technologies,” according to Zhang.

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