Why are viruses such a problem for transplant patients?
Viruses are common following organ transplants because modern immunosuppression impairs the ability to recognize and eliminate viruses. Organ transplants are very similar to a virally infected cell in that they are a normal human cell that has unusual proteins on the surface. These proteins are called major histo-compatibility (MHC) antigens in the case of an organ transplant and viral proteins in the case of a virally infected cell. Bacteria and fungi, on the other hand, are completely different and the body responds to these sorts of infections differently than it responds to viral infections. The body fights off viral infections in a way very similar to the way it “rejects” organ transplants. Therefore, since modern immunosuppression is aimed specifically at the immune responses against transplanted organs, the immune responses against viruses are impaired as well.
