MECHANISM OF IMMUNITY IN HOSTS TO CHRONIC INFECTIONS IN WILD CONDITIONS

Open Access
Author:
Creppage, Kathleen Elizabeth
Area of Honors:
Immunology and Infectious Disease
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Isabella Cattadori, Thesis Supervisor
  • James Endres Howell, Honors Advisor
Keywords:
  • immunity
  • wild conditions
Abstract:
ABSTRACT BACKGROUND: The aim of this study was to examine a pool of samples (one year, specifically) for evidence of arrested development of Trichostrongylus retortaeformis (TR) in wild rabbit guts. Prior studies have indicated that a variety of parasites in rabbits, sheep, and cattle move into this arrested state as a method of protection from both the host immune environment and the ecological environment. Patterns in arrested development can yield descriptive data about host immunity, population dynamics, and local climatic conditions over time. RESULTS: There were a number of trends among arrested larvae and host characteristics. When comparing the numbers of recovered larvae over a period of 12 months, there was a steady increase in fall and winter, a decline in the spring, a sharp increase in April before the new offspring are born, and then another decline in the summer months. Arrested larval load rose with increasing age until about age 7, where it began to decline as the rabbits reached late adulthood and their immune systems weakened. CONCLUSION: The results suggest two underlying mechanisms for arrested development of T. retortaeformis in the rabbit host. The first is likely a seasonal response; in the later fall and harsher winter months, the larvae arrest their development as a means of protection. The second is an immune mechanism, indicated by the large recovery of stage 4 larvae (L4s) in April when the majority of female rabbits are pregnant and probably shed larvae more rapidly. These results support prior research and beliefs concerning hypobiosis in rabbits, ruminants and other grazing animals. Further research with several consecutive years of samples could unearth more descriptive patterns and associations.