Recently discovered tunneling nanotubes may be responsible for the spread of HIV and prion infectivity from cell to cell, scientists have found.

At 50 to 200 nanometers thick, they are wide enough to allow proteins to pass through, and can span distances of several cell diameters, wiggling around obstacles to connect the insides of two cells some distance apart. Nanotubes may also play a role in tumors becoming resistant to chemotherapy, so a drug that inhibits the growth of nanotubes could reduce the resistance to chemotherapy.