Changes in some biophysical characteristics of African horsesickness virus (no. 3922) during attenuation

dc.contributor.advisorKipps, A
dc.contributor.advisorPolson, A.
dc.contributor.authorRussell, B.W
dc.date.accessioned2020-05-18T13:39:25Z
dc.date.available2020-05-18T13:39:25Z
dc.date.issued1967
dc.date.updated2020-04-16T11:56:50Z
dc.description.abstractAfrican horsesickness virus (No.3922, Type 7), attenuated for the horse by serial passage in suckling mouse brain, was studied at various passage levels to determine whether any change in the biophysical characters of the infectious particles had occurred. during the process of attenuation. Such changes were indeed observed. Propagation of the virus in tissue culture was accomplished only after the modification of standard culture media by the addition of egg white, a complex substance containing a number of proteins including the enzyme lysozyme. Some evidence is presented to show that the presence of egg white materially assisted in the successful cultivation of horsesickness virus; as well as in the formation of plaques in monolayers ·of cultured cells. Electron micrographs of horsesickness virus obtained from these cultured cells, and the results of a study of the fine structure of infected mouse nervous tissue, are presented. A remarkable change in the buoyant density of the infectious particles of this horsesickness virus was found to occur during attenuation. The 'wild' or virulent strain was found to consist mainly of particles of density 1.26 gm/ml. The attenuated strain however proved to be composed of particles with deneities quite different from that of the wild strain, predominantly 1.21 and 1.34 gm/ml. This alteration of the buoyant appeared to be directly related to the degree of attenuation. Studies in electrophoresis using a newly designed apparatus showed that the wild strain of horsesickness virus is homogeneous in its migration in an electric field. The attenuated strain showed a changed electrophoretic pattern· indicating the presence of particles of different mobilities. As in density gradient analysis, electrophoresis showed a fundamental difference between the wild and attenuated strains of this virus. It was possible also to show a correlation between the slowly migrating component of the attenuated strain and the fraction of higher density. The sedimentation coefficient of the infectious particles of the No.3922 strain of horsesickness virus was studied at various stages of attenuation ·and the particle size at three passage levels were calculated. The particle size and other characteristics determined in this way were compared with the results of measurements obtained from ultrafiltration of the virus through collodion membranes. It was found that the diameter of the infectious particles of the attenuated strain is greater than that of the wild strain. This study shows that physical measurements may be used to give
dc.identifier.apacitationRussell, B. W. (1967). <i>Changes in some biophysical characteristics of African horsesickness virus (no. 3922) during attenuation</i>. (). ,Faculty of Science ,Animal Demography Unit (ADU). Retrieved from en_ZA
dc.identifier.chicagocitationRussell, B.W. <i>"Changes in some biophysical characteristics of African horsesickness virus (no. 3922) during attenuation."</i> ., ,Faculty of Science ,Animal Demography Unit (ADU), 1967. en_ZA
dc.identifier.citationRussell, B.W. 1967. Changes in some biophysical characteristics of African horsesickness virus (no. 3922) during attenuation. . ,Faculty of Science ,Animal Demography Unit (ADU). en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Russell, B.W AB - African horsesickness virus (No.3922, Type 7), attenuated for the horse by serial passage in suckling mouse brain, was studied at various passage levels to determine whether any change in the biophysical characters of the infectious particles had occurred. during the process of attenuation. Such changes were indeed observed. Propagation of the virus in tissue culture was accomplished only after the modification of standard culture media by the addition of egg white, a complex substance containing a number of proteins including the enzyme lysozyme. Some evidence is presented to show that the presence of egg white materially assisted in the successful cultivation of horsesickness virus; as well as in the formation of plaques in monolayers ·of cultured cells. Electron micrographs of horsesickness virus obtained from these cultured cells, and the results of a study of the fine structure of infected mouse nervous tissue, are presented. A remarkable change in the buoyant density of the infectious particles of this horsesickness virus was found to occur during attenuation. The 'wild' or virulent strain was found to consist mainly of particles of density 1.26 gm/ml. The attenuated strain however proved to be composed of particles with deneities quite different from that of the wild strain, predominantly 1.21 and 1.34 gm/ml. This alteration of the buoyant appeared to be directly related to the degree of attenuation. Studies in electrophoresis using a newly designed apparatus showed that the wild strain of horsesickness virus is homogeneous in its migration in an electric field. The attenuated strain showed a changed electrophoretic pattern· indicating the presence of particles of different mobilities. As in density gradient analysis, electrophoresis showed a fundamental difference between the wild and attenuated strains of this virus. It was possible also to show a correlation between the slowly migrating component of the attenuated strain and the fraction of higher density. The sedimentation coefficient of the infectious particles of the No.3922 strain of horsesickness virus was studied at various stages of attenuation ·and the particle size at three passage levels were calculated. The particle size and other characteristics determined in this way were compared with the results of measurements obtained from ultrafiltration of the virus through collodion membranes. It was found that the diameter of the infectious particles of the attenuated strain is greater than that of the wild strain. This study shows that physical measurements may be used to give DA - 1967 DB - OpenUCT DP - University of Cape Town KW - African horsesickness virus KW - virus LK - https://open.uct.ac.za PY - 1967 T1 - Changes in some biophysical characteristics of African horsesickness virus (no. 3922) during attenuation TI - Changes in some biophysical characteristics of African horsesickness virus (no. 3922) during attenuation UR - ER - en_ZA
dc.identifier.urihttps://hdl.handle.net/11427/31899
dc.identifier.vancouvercitationRussell BW. Changes in some biophysical characteristics of African horsesickness virus (no. 3922) during attenuation. []. ,Faculty of Science ,Animal Demography Unit (ADU), 1967 [cited yyyy month dd]. Available from: en_ZA
dc.language.rfc3066eng
dc.publisher.departmentAnimal Demography Unit (ADU)
dc.publisher.facultyFaculty of Science
dc.subjectAfrican horsesickness virus
dc.subjectvirus
dc.titleChanges in some biophysical characteristics of African horsesickness virus (no. 3922) during attenuation
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
Files
Original bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
thesis_sci_1967_russell_b_w.pdf
Size:
6.94 MB
Format:
Adobe Portable Document Format
Description:
License bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
license.txt
Size:
0 B
Format:
Item-specific license agreed upon to submission
Description:
Collections