Degree Type

Dissertation

Date of Award

1984

Degree Name

Doctor of Philosophy

Department

Veterinary Microbiology and Preventive Medicine

Abstract

Reference strains and field isolates of herpesviruses recovered from cattle in the U.S. were compared by restriction endonuclease (RE) analysis and the indirect fluorescent antibody test (IFAT). As a result of this comparison five major biotypes of bovine herpesvirus were defined. These types were: (1) infectious bovine rhinotracheitis virus (Bovine herpesvirus 1: BHV-1); (2) bovine herpes mammillitis virus (Bovine herpesvirus-2: BHV-2); (3) malignant catarrhal fever virus (MCFV: Herpesvirus alcelaphinae); (4) the group of slow cytopathic effect (CPE) isolates represented by the prototype strain Movar 33/63 (bovine cytomegalovirus candidate) and (5) the syncytia-forming Pennsylvania 47 strain. A low but consistent level of serologic cross-reactivity was detected among MCFV, the Movar group and Pennsylvania 47. No isolate from American domestic cattle was similar to the African MCFV, which has been sporadically isolated in the U.S. from exotic ruminants. The possibility of Pennsylvania 47 strain being the causal agent of non-wildebeest-associated MCF is discussed. Several non-syncytial, slow CPE strains, which were recovered from dissimilar clinical syndromes and were serologically related to Movar 33/63, exhibited very similar DNA RE cleavage patterns, confirming their identity as members of a single type. Rabbits were inoculated with a cell-culture propagated suspension of the strain Movar 33/63, and sacrificed at different intervals between 3 days and 42 weeks postinfection (PI). Cell-free infectious virus was detected only in conjunctival secretions, buffy coat and spleen homogenates up to 7 days PI. Beyond this brief acute replication period, co-cultivation or explanation was required for the detection of viral infectivity. The spleen, the only organ from which virus was consistently recovered, exhibited the highest infectious titers as detected by infectious center assay. The use of several cell fractionation techniques allowed separation of B-enriched, T-enriched and non-T, non-B cell fractions. Infectivity during the acute and persistent phases of the infection was associated with the non-T, non-B population which was highly enriched in adherent and non-adherent spleen mononuclear phagocytes. No virus was isolated from either T or B cells. No histologic injury was detected in the organs. A protocol for optimal detection of Movar 33/63-specific nucleic acids by cytohybridization has been developed.

DOI

https://doi.org/10.31274/rtd-180813-12824

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Fernando Abel Osorio

Language

en

Proquest ID

AAI8505857

File Format

application/pdf

File Size

164 pages

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