Correlating soft X-ray tomography with super-resolution fluorescence microscopy brings a new method of evaluating virosome solutions for vaccine development

Virosomes, which are like non-replicating “artificial viruses,” are capable of delivering vaccination antigens to targeted sites in a host cell. In general, a virosome is a liposome with the virus’s envelope glycoproteins either physically bound to the virosome’s surface or chemically cross-linked to it.

When delivered to the cell, they initially trigger an immune response that is “anti-viral’’. Additionally, host cells can express the viral antigen(s) intracellularly causing a second wave of antigen exposure and a stronger immune stimulation.

In the paper referenced below, a 3D correlative microscopy methodology, incorporating cryo-Soft X-ray Microscopy (cryo-SXM) and cryo-Structured Illumination Microscopy (cryo-SIM), has been used to provide a reliable analytical method for characterising Zika- and Chikungunya-derived Virosomes. This includes changes in cellular ultrastructure following viral infection as well as the ability to deliver promised immunity.

The paper has concluded that a correlative cryo-microscopy approach using both cryo-SXM and cryo-SIM allows the characterisation of virosome vaccine candidates and could efficiently complement protocols currently in place for similar vaccine formulations. This result highlights the possibility of the integrated method during early pre-clinical trials to validate cell survival and recovery after virosome integration, similar to immunization in animals or people. This is significant because it is important to demonstrate that vaccination candidates do not harm host cells, but rather are efficient enough to trigger immune responses without eradicating cell populations.

Correlative imaging using super-resolution fluorescence microscopy and soft X-ray tomography at cryogenic temperatures provides a new way to assess virosome solutions for vaccine development

Chidinma A.Okolo, Maria Harkiolaki,