Certain Factors Determining the Course of Virus-Induced Tumors

Abstract

When retrogressing or enlarging, the chicken tumors due to filtrable causes and the Shope rabbit papilloma conduct themselves like other neoplasms. 1 Their course is determined by a variety of influences. The papilloma is especially suited to the study of these because of its accessibility and discrete character.

Influence of the Initial Virus State. Shope virus from some sources gives rise to progressively enlarging papillomas, and that from others to growths which tend to disappear. Virus artificially attenuated (by heating) causes infrequent, inactive growths which eventually retrogress. 2 In the literature on chicken tumors similar facts find larger illustration.

Host Conditions Affecting the Virus. The blood serum of rabbits carrying the papilloma neutralizes the Shope virus in vitro. 3 To ascertain whether the course of the growth is influenced by the circulating antibodies we have tattooed or intradermally inoculated the virus at many points on the sides of 2 comparable groups of domestic rabbits, in addition rubbing it into broad scarified areas on the abdomen of one of the groups, producing in this way confluent papillomatous masses which appeared sooner and enlarged much faster than did the growths on the sides. The latter were all charted at short intervals, and the virus-neutralizing power of the hosts' sera was determined from time to time. Such power was absent prior to inoculation and its rate of development, though differing somewhat from individual to individual, on the whole varied pari Passu with the increase in bulk of the papillomatous tissue. The power appeared sooner and became much greater in the animals developing large abdominal masses, yet the growths on their sides differed no whit in magnitude and course from those of the control animals. A negative outcome of reinoculation with the virus, on the other hand, proved directly referable to the possession of neutralizing power by the blood.