The most conclusive evidence that viruses cause cancers was provided by
A)finding oncogenes in viruses.
B)the presence of antibodies against viruses in cancer patients.
C)cancer that developed in chickens following injection of cell-free filtrates.
D)treating cancer with antibodies.
E)some liver cancer patients having had hepatitis.

Question

Quizplus · Accepted Answer

The injection of cell-free filtrates from infected chickens into healthy chickens produced cancer, demonstrating that the virus was the causative agent. This was first demonstrated by Francis Peyton Rous in 1911 and provided the first conclusive evidence for the viral cause of cancers. Choice A is also relevant as viruses with oncogenes can cause cancer, but this was not the first evidence for viral causation. Choice B is not conclusive as antibodies can be present in response to the cancer rather than the virus. Choice D is not relevant to this question as it is discussing treatment rather than causation. Choice E is also relevant to viral causation, but not the most conclusive evidence.

The Most Conclusive Evidence That Viruses Cause Cancers Was Provided