One-half of the newborn hamsters orally inoculated with polyoma virus developed tumors within the interval of observation, whereas all of the newborn hamsters inoculated by the more conventional routes of virus inoculation (the subcutaneous and the intraperitoneal routes) eventually developed tumors. The death rate in the orally infected hamsters was less than that of either of the other two inoculated groups, and the age at occurrence of the first death in this group of hamsters was several days later than in the other two groups. In the course of tumor formation in the heart, lungs, liver, and kidney of the inoculated animal, significant change in an organ's weight was found to occur during the same age interval in which significant elevations of serum enzyme values occurred.

Polyoma virus was cultivated on mouse embryo primary cell monolayers, extracted by freeze-thaw techniques, concentrated by centrifugation, assayed by hemagglutination of guinea pig erythrocytes. and stored in the frozen state until used for hamster inoculation.

One hundred and twenty-seven Syrian hamsters were obtained by breeding in this laboratory, and the inoculated ones were grouped according to the route of polyoma virus inoculation; oral, subcutaneous. and intraperitoneal. Another group of hamsters were left uninoculated. When the hamsters became moribund, or before sacrifice, blood was extracted for lactic dehydrogenase and alkaline phosphatase serum enzyme studies.

Autopsy data of animals that had died or were sacrificed included the weights of the heart, lung, liver, kidney, and the total body weight of the hamster. Also recorded at autopsy was the presence or absence of gross tumors in these four organs.

The Rank Sum Test was used to analyze the results of the serum enzyme and organ weight studies within the framework of the age intervals when significant changes of these values were present. Correlation between elevated serum enzyme values and the change in weight of an organ were also made.

Significant elevations of lactic dehydrogenase values as demonstrated by the Rank Sum Test occurred within the same age interval in which the significant heart weight elevations occurred in animals with polyoma virus inoculated by all three routes.

Significant elevation of alkaline phosphatase values occurred only in orally inoculated hamsters. A significant decrease in liver weight also began during this same age interval and was related to the elevated alkaline phosphatase.

Two important conclusions suggested by this study are: (1) orally-inoculated polyoma virus was able to retain its tumorigenic property, and (2) serum enzyme studies may be used to detect early tumor development in the polyoma induced tumor-hamster system.

LLU Discipline





Graduate School

First Advisor

Robert L. Nutter

Second Advisor

Charles E. Winter

Third Advisor

Bo Ying Wat

Fourth Advisor

Arthur E. Dalgleish

Fifth Advisor

Leonard R. Bullas

Degree Name

Master of Science (MS)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Polyomaviruses; Tumor Virus Infections



Page Count

x; 97

Digital Format


Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


Loma Linda University Electronic Theses and Dissertations

Collection Website



Loma Linda University. Del E. Webb Memorial Library. University Archives

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Microbiology Commons