A method has been developed that will allow for the first time to see how viruses are created

Researchers at Harvard, including an Israeli, succeeded in developing a system capable of tracking nanometer-sized viruses on a sub-millisecond time scale

[Translation by Dr. Nachmani Moshe]
Researchers have succeeded in developing a system capable of tracking nanometer-sized viruses on a sub-millisecond time scale. The method, developed by researchers from the School of Engineering and Applied Sciences at Harvard University, is the first step in the ability to track proteins and individual genomic molecules that move at high speeds during the formation of viruses.

Want to make a virus? It's simple: combine a molecule of genetic material, DNA or RNA, together with a handful of proteins, mix them and within a second you will get an active virus. Viruses, such as the flu virus, spread so efficiently that they can be particularly lethal to their hosts, as a result of their ability to spontaneously form in large quantities. If researchers understand how viruses are formed, they will also be able to design drugs that prevent viruses from forming in the first place. At the same time, the exact mechanism by which viruses are created has remained a mystery for a long time due to the fact that this creation occurs extremely quickly and on a minimal scale in terms of length. The research was led by Vinothan Manoharan, a professor of chemical engineering and physics, and has long been published in the scientific journal ACS Nano.

"Our goal was to understand how viruses manage to organize themselves spontaneously, at such a fast rate and in such a durable manner," said Yoav Lahini, a research associate and one of the two lead authors of the article. Identifying essential intermediate steps during formation could help researchers understand how to interfere with this process, Lahini explains. Understanding the mechanism could also help engineers design better and more efficient synthetic nanomaterials that can be obtained spontaneously.

There are two main challenges in tracking the formation of viruses: speed and size. Despite the fact that fluorescence microscopy allows the identification of individual proteins, the fluorescent chemical compound that emits the photons does so at a rate that is too slow to observe the formation process. The situation is similar to the case where one tries to observe the movement of the flying wings of the hummingbird bird using a "stop-image" type camera; She perceives parts of the process, but the essential parts are missing. Extremely small particles, such as the protein envelope of viruses, can be observed by the way they scatter light. In this method, known as elastic scattering, an unlimited amount of photons is emitted in one moment, a fact that solves the problem of speed. However, the photons also react with dust particles further scattering the light, and there are defects in the optical path, and therefore all these factors interfere with tracking the tiny particles.

In order to solve these problems, the team decided to take advantage of the extraordinary quality of optical fibers, perfected after years of research in the telecommunications industry. The researchers designed a new optical fiber with a nanometer-sized channel that is smaller than the wavelength of light, a channel that runs along the inside of the fiber's silica core. This channel is filled with a liquid containing nanoparticles, so that when the light passes through the fiber core, it is scattered by the nanoparticles in the channel and processed by a microscope located above. With the help of the new system, the researchers were able to observe the movement of viruses with a diameter of 26 nanometers at a rate of thousands of measurements every second. "These are the smallest viruses ever observed on a sub-millisecond time scale, which is similar to the time scale of the formation mechanism of viruses," said one of the research partners. The next step the researchers plan is to track not only individual viruses, but also the individual virus proteins, which scatter light in a hundred to a thousand times smaller amount than an entire virus.

"This research is an advanced step in observing and measuring the formation of viruses," says the researcher. "Viral infection involves many and complex molecular and cellular pathways, but the process of self-aggregation occurs in many different viruses. The simple technology, which is also cheap, convenient and scalable, could provide a new, cost-effective and efficient way to understand and measure viruses. From the point of view of basic physics, understanding the mechanism of self-assembly in systems that have evolved in nature could be an important milestone in the study of complex systems."

for the scientific article

The news about the study