One of the challenges facing the deployment of oncolytic viruses to fight tumors in humans is the immune response they generate. Naturally, we would think that viruses for which most of the target population has immunity to (e.g. those abrogated by the MMRV vaccine) are ineligible therapeutic candidates, but researchers are finding new ways to make host immunity a non-issue. For example, using Measles Virus (MV) to fight cancer would normally be inefficient because most people are vaccinated at an early age. Because strong immunosuppression during oncolytic therapy is a risky option, scientists have developed a method of 'shielding' the pathogen from the host.
Researchers from the Mayo Clinic replaced measles virus glycoproteins with modified CDV (canine distemper virus) glycoproteins that are able to attach to cancer cells via an attached antibody. The shielded MV was successful in eliminating tumors in murine models and was also successful in evading human antibodies. THis study was a proof of concept for chimeric viruses.