Passage of Shope's Rabbit Fibroma Virus through One-Day-Old Mice. ∗

Abstract

Summary

The fact that the virus titer, as shown by intracutaneous inoculations into rabbits, declined only slightly in the 3 serial passages through mice, despite a 250-fold dilution at each passage, indicates the possibility of virus proliferation. However, too few experiments were performed to establish this relationship clearly. There is no doubt that the virus can persist in the brain of the living mouse (one-day-old) for periods at least up to a month. With further attempts at mouse-to-mouse passages it appears likely that the virus can be established in this host.

While fibromas of domestic rabbits that were produced by direct inoculation of tumor suspensions are usually non-infective¶ for arthropods, those tumors resulting from arthropod transmission from the natural cottontail rabbit hosts are often infective(4). Treatment of the recipient domestic rabbits with x-rays or carcinogens prior to infection with the virus also effectively changes the infectivity of the resultant tumors so that they are infective for arthropods (4,5). It now appears that passage of the virus through one-day-old mouse brain, which does not seem to affect the mouse, does alter the virus so that subsequent inoculations into domestic rabbits produce infective tumors.