The electron microscope had been invented in 1931 by German researcher Max Knoll, and improved by Delft engineering student Jan Bart Le Poole. During the post-war years, this made the Technische Hogeschool (Technical College) in Delft the first and only place in the Netherlands to have such a microscope.

For virology, the advent of the electron microscope was an extremely important development. With the help of the electron the three shapes of virus particles that were discovered: rod-shaped, spherical, and filamentous.

Clearly, this was only the start of the many discoveries made possible by research with the increasingly stronger electron microscope.

In 1948, during his leave in the Netherlands, Thung and his Wageningen colleague Jan van der Want (1921-2007) conducted research on various plant viruses using an electron microscope in Delft.