Final answer:
The statement is true. Prions, which are infectious agents composed entirely of proteins, can potentially aid in an infectious agent or increase susceptibility to it.
Step-by-step explanation:
The statement that some doubters of the protein-only hypothesis for prions think that prions somehow either directly aid in infectious agent such as an unknown virus or increase susceptibility to the agent is True.
Prions are infectious agents composed entirely of proteins and do not contain DNA or RNA. They are thought to contribute to several brain disorders, including mad cow disease and Creutzfeldt-Jakob disease. While the protein-only hypothesis suggests that prions can replicate and cause disease without the presence of a traditional infectious agent such as a virus or bacteria, some doubters believe that prions may interact with other unknown factors to cause or facilitate infection.