The simian vacuolating virus (SV40) can infect both human and apes and is of interest as capsule for drug delivery since it can efficiently infect a wide range of human cells. The icosahedral virus capsid is assembled from VP1 pentamers, and this assembly is stimulated by the presence of dsDNA. However, the real-time assembly process of SV40 and viruses in general is poorly understood limiting among other things our ability to manipulate capsid re-assembly in vitro for therapeutic purposes.Here, we show the real-time assembly of capsid around dsDNA employing dual-trap optical tweezers (OT). Protein assembly around the DNA leads to a drastic change in the contour length, which is readily observed when dsDNA is incubated with VP1 pentamers, indicating both kinking and crosslinking. Additionally, a new technology, acoustic force spectroscopy (AFS) capable to apply very low constant forces, provides indications of substantial capsid-like-structure formation observable as real-time shortening of DNA in the presence of VP1 combined with major rupture events when stretching the DNA-protein structure afterwards. In order to obtain visual information about protein coverage and arrangement on DNA, we generated atomic force microscope (AFM) images. In these images we observe significant cluster formation on DNA providing a good indication that we observe partial assembly. These results reveal that we can indeed track the assembly of viral capsids and visualize intermediates. This in turn provides a window into the complex kinetics of viral capsid formation.