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W C Lawrence

Publications and source records attributed to W C Lawrence.

28 records · Page 2Linked to original sources
PubMed1976

Purification of equine herpesvirus type 1.

A method for the purification of enveloped infectious equine herpesvirus type 1 (EHV-1) is presented. Virus from cell culture fluids harvested at 48 h post infection was concentrated by sedimentation and partially purified by differential precipitation with ammonium sulphate. The final steps of purification consisted of two cycles of flotation of virus in pre-formed CsCl density gradients. Yields of infectious virus were about 30% (18 to 44%) of that present in starting material. As judged by electron microscopy, mixed radioisotope labelling, and absence of phosphohydrolase, virus preparations possessed a high degree of purity. Sedimentation of EHV-1 into CsCl density gradients resulted in low recovery of infectious virus. Flotation of virus in CsCl gradients, however, was not deleterious to infectivity of viral preparations.

Ammonium Sulfate↗
PubMed1976

Morphological components of herpesvirus. II. Preservation of virus during negative staining procedures.

The disruption of envelopes and the fragmentation of capsids of equine herpes-virus type I observed in negatively stained samples were attributed to viral dehydration on carbon films during preparation for electron microscopy. Prior fixation of virus with OSO4 or glutaraldehyde and subsequent application of negative stain before drying minimized envelope disruption and virtually eliminated the occurrence of capsomere sheets and broken capsids. This sample procedure significantly improves electron microscopic evaluation of herpesvirus samples.

Animals↗
PubMed1974

Morphological components of herpesvirus. I. Intercapsomeric fibrils and the geometry of the capsid.

Highly purified equine herpesvirus type 1 (EHV-1) and herpes simplex virus type 1 (HSV-1) were observed by electron microscopy in various stages of disintegration. Under the conditions used, envelopes of virions usually were fragmented, and virus capsids collapsed in situ into flattened sheets of capsomeres. A matrix of intercapsomeric fibrils was observed. Evidence suggesting that the capsid hexamer has threefold structural symmetry is presented.

Capsid↗
PubMed1971

Evidence for a relationship between equine abortion (herpes) virus deoxyribonucleic acid synthesis and the S phase of the KB cell mitotic cycle.

Autoradiographic analyses of deoxyribonucleic acid (DNA) synthesis in randomly growing KB cell cultures infected with equine abortion virus (EAV) suggested that viral DNA synthesis was initiated only at times that coincided with the entry of noninfected control cells into the S phase of the cell cycle. Synchronized cultures of KB cells were infected at different stages of the cell cycle, and rates of synthesis of cellular and viral DNA were measured. When cells were infected at different times within the S phase, viral DNA synthesis was initiated 2 to 3 hr after infection. However, when cells in G1 and G2 were infected, the initiation of viral DNA synthesis was delayed and occurred only at times corresponding to the S phase. The times when viral DNA synthesis began were independent of the time of infection and differed by as much as 5 hr, depending on the stage of the cell cycle at which cells were infected. Viral one-step growth curves were also related to the S phase in a manner which indicated a relationship between the initiation of viral DNA synthesis and the S phase. These data support the concept that initiation of EAV DNA synthesis is dependent upon some cellular function(s) which is related to the S phase of the cell cycle.

Animals↗
PubMed1971

Deoxyribonucleic acid synthesis in synchronized mammalian KB cells infected with herpes simplex virus.

We examined the patterns of host cell and virus deoxyribonucleic acid (DNA) synthesis in synchronized cultures of KB cells infected at different stages of the cell cycle with herpes simplex virus (HSV). We found that the initiation of HSV DNA synthesis, we well as the production of new infectious virus, is independent of the S, G1, and G2 phases of the mitotic cycle of the host cell. This is in contrast to data previously found with equine abortion virus. Because HSV replicates independently of the cell cycle, we were able to establish conditions that would permit the study of rates of HSV DNA synthesized in logarithmically growing cells in the virtual absence of cellular DNA synthesis. This eliminates the need for separation of viral and cellular DNA by isopycnic centrifugation in CsCl. We found that HSV DNA synthesis was initiated between 2 to 3 hr after infection. The rate of DNA synthesis increased rapidly, reaching a maximum 4 hr after infection, and decreased to 50% of maximum by 8 hr. Evidence is also presented which suggests that HSV infection can inhibit both the ongoing synthesis of host DNA as well as the initiation of the S phase.

Carcinoma↗
PubMed1967

Intracellular uncoating of type 5 adenovirus deoxyribonucleic acid.

Highly purified, (32)P-labeled type 5 adenovirus was employed to study "uncoating" of viral deoxyribonucleic acid (DNA)-defined as the development of sensitivity to deoxyribonuclease. Viral infectivity and radioactivity adsorbed to KB cells at the same rate, and significant amounts of (32)P did not elute from cells throughout the eclipse period. Kinetic studies of viral penetration, eclipse of infectivity, and uncoating of viral DNA indicated that the three events were closely related temporally, that the rates of each were similar, and that they were completed within 60 to 90 min after infection. Viral penetration, eclipse, and uncoating proceeded normally under conditions which blocked protein synthesis, but they did not occur at 0 to 4 C. Neither viral DNA nor viral protein was degraded to acid-soluble material during the eclipse period. The nature of adenovirus DNA was studied after it was converted intracellularly from deoxyribonuclease-resistant to deoxyribonuclease-susceptible. Intact virions centrifuged in sucrose gradients had a sedimentation coefficient of approximately 800, and viral DNA sedimented as a particle of about 30S. Infection of KB cells with purified (32)P-labeled virus yielded deoxyribonuclease-susceptible viral nucleic acid which was in particles with sedimentation coefficients of 350 to 450S, i.e., greater than 10 times faster than DNA obtained from purified virions which had been disrupted by exposure to pH 10.5. When the DNA from disrupted virions was mixed with cell lysates, its sedimentation characteristics were essentially unchanged by the presence of cellular material.

Adenoviridae↗