Unusual filterable oncogenic agent isolated from horizontally transmitted Syrian hamster lymphomas

Area of Science:

• Oncology
• Virology
• Experimental Pathology

Background:

• An outbreak of horizontally transmitted malignant lymphoma occurred in Syrian hamsters.
• Conventional oncogenic viruses were not detected, but an infectious agent was implicated.

Purpose of the Study:

• To isolate and characterize the infectious agent responsible for hamster lymphomas.
• To determine if the isolated agent could induce lymphomas in susceptible hamsters.

Main Methods:

• Cell-free isolation of an agent from lymphoma tissues.
• Subcutaneous injection of the agent into newborn Syrian hamsters.
• Reisolation of the agent from induced lymphomas.

Main Results:

• Successful cell-free isolation of a filterable agent.
• The agent induced lymphomas efficiently in injected hamsters.
• The agent was reisolated from induced lymphomas, confirming reproducibility.

Conclusions:

• The isolated agent exhibits characteristics of a mammalian viroid.
• This agent is a novel, infectious cause of hamster malignant lymphoma.
• The findings suggest a new class of infectious agents causing cancer in mammals.