Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Veterinary Pathology


This thesis is presented in the alternate format and it is composed of three interrelated but independent manuscripts;The first manuscript, titled "Pseudorabies in cattle: a review," is a critical rather than a historical review of much of the literature available on the subject. It focuses on the problem from the perspective of pathogenetic mechanisms, highlights opportunities for further research, raises questions about accepted views, and suggests that recently developed techniques may prove useful in gaining new insights about this particular infectious process;The second manuscript is titled "Comparative usefulness of tissue fixatives for in situ viral nucleic acid hybridization." It deals with the student's efforts to adapt one of the newer research techniques for its use in pseudorabies-infected cattle tissues. The work was actually carried out with mice in order to limit expenses and conserve resources. It established that the available hybridization probes could detect the nucleic acids of pseudorabies virus effectively and specifically. In addition, the paper offers a detailed account of the various fixatives tested for degree of usefulness and compatibility with in situ hybridization. A modification of Carnoy's fluid (MOCA) was devised and found to be well-suited for fixation of bulky cattle tissues;The third manuscript is titled "Reproducibility of in situ hybridization when applied to MOCA and formalin-fixed pseudorabies-infected cattle tissues." It documents the reproducibility of in situ hybridization as well as its degree of correspondence to quantitative virus isolation when it was applied to a wide range of MOCA-fixed, pseudorabies-infected bovine tissues. In addition, the paper offers the results of a limited retroactive study carried out with 7 year old formalin-fixed infected neural bovine tissues. Reliable specific in situ hybridization occurred in MOCA-fixed neural tissues, but suspicious, seemingly false positive reactions were not uncommon in other tissues, particularly those rich in lymphocytes and macrophages. A strong hybridization signal was present in the formalin-fixed material despite its age, so that type of material is suitable for retrospective studies.



Digital Repository @ Iowa State University,

Copyright Owner

Harold Antonio McAllister



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File Size

106 pages