Passenger virus

A passenger virus is a virus that is frequently found in samples from diseased tissue, such as tumours, but is not a contributing factor in causing the disease.
Experimental demonstration of passenger status.
Proving that a virus has no causative role can be difficult. Although none of the following signs is definitive, evidence that a virus found in diseased tissue might be passenger only rather than a causative agent includes:
Examples.
A well-established example is lactate dehydrogenase virus, which is often found in mouse tumours. GB virus C and Chandipura virus are possible examples in humans. It has also been suggested that a virus related to Alcelaphine herpesvirus 1 is a passenger virus that, unlike AHV1 itself, doesn't cause bovine malignant catarrhal fever. The discredited Duesberg hypothesis posits that HIV is a passenger virus in the etiology of AIDS.