Researchers use high-resolution imaging to observe HIV infection process in the cell nucleus Scientists at EMBL Heidelberg and at the Zentrum für Infektiologie at Heidelberg University Hospital have succeeded for the first time in imaging HIV during transport into the nucleus of an infected cell. The electron tomographic images show the protein envelope of the virus passing through one of the nuclear pores - the openings in the membrane around the nucleus that allow molecules in and out. The scientists found that the virus passes through the nuclear pore intact, only breaking apart inside the nucleus, where it releases its genetic information. This clarifies an important mechanism by which the virus's genetic material is integrated into the genome of the infected cell.