Cell cycle-dependent changes in lymphoid cells infected with feline leukaemia virus

Toth, Sarah R (1980) Cell cycle-dependent changes in lymphoid cells infected with feline leukaemia virus. PhD thesis, University of Glasgow.

Abstract

The aim of this study was to investigate a variety of cell cycle-related changes in FeLV-infected lymphoid cells. The cell cycle and the use of synchronised cells played a major role in most of the experiments carried out. The Introduction, therefore, contains an outline of the concept of the mammalian cell cycle and a discussion of some of its practical applications. In Chapter One, synchronising techniques and life cycle analysis methods are described in general, while the methods used during the course of this study are presented in more detail. The relationship between a distinct phase of the cell cycle and the release of FeLV is examined in Chapter Two. By using two assay systems and applying two different synchronising methods it was established that virus production is cell cycle-dependent. It occurs in the period in both homologous and heterlogous cell lines. Changes in morphology during synchronous growth were examined by transmission (TEM) and by scanning (SEM) electron microscopy (Chapter Three). An analysis of morphological data obtained by TEM and SEM revealed that synchronised cells of the cat lymphoblastoid line, FL74, exhibited distinct ultra structural variations which were closely related to the cell cycle. It was also established, for the first time, that the surface structure of lymphoid cells showed cell cycle-specific changes which were highly characteristic. When the number of budding C-type particles was counted on cells which were morphologically characterised in this way it was found that in both TEM and SEM preparations the early-G1-cells were releasing the highest number of virus particles. An investigation of the expression of viral antigens and FOCMA in synchronised cells was the subject of a further study described in Chapter Four. By using immunofluorescence techniques, evidence was obtained for the cell cycle-dependent expression of viral and FOCMA antigens. The viral structural antigens, pl5 and p30, and the major envelope glycoprotein gp70 reached a peak in the early-G1 phase, whereas, FOCMA was expressed 14 hours later in the late-G1 period, FOCMA peaks were detected on FeLV-infected feline but not on FeLV-infected canine cell lines. This suggested that FOCMA was distinct from the viral antigens. In order to investigate the kinetics of FeLV production and to explore some of the regulatory mechanisms responsible for the expression of antigens in FL74 cells, the effects of various metabolic inhibitors were examined (Chapter Five). It was found that virus production and antigen expression were regulated by a complex cell cycle-dependent synthesis of RNA, mRNA, viral and cellular proteins, which in turn were co-ordinated by mitosis. Finally, in Chapter Six, the occurrence and distribution of feline leukaemia virus-associated antigens were examined by immuno- electron microscopy. Ferritin labelling of cells prefixed in glutaraldehyde revealed that the cell surface antigens were randomly distributed. gp70 was found to be the most plentiful followed by FOCMA, p30 and pl5 in descending order. Antisera to pl5 and p30 did not stain intact viral particles, while the non-budding areas of the cell membrane were labelled. Both gp70 and FOCMA antisera stained viral particles as well as the non-budding areas of the cell membrane. In order to investigate the unexpected labelling of viral particles by FOGMA antisera, an immunofluorescence-immunoferritin study in capping conditions and competition experiments were performed. The results indicated that FOCMA was distinct from gp70 and that labelling of virions was possibly due to the undetected presence of neutralising antibodies in the FOCMA antisera used. Ferritin labelling of synchronised FL74 cells showed that in the early-G1 phase considerably more antigenic sites per unit length were expressed than in the S phase.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: W FH Jarrett
• Keywords: Veterinary science, Cellular biology
• Date of Award: 1980
• Depositing User: Enlighten Team
• Unique ID: glathesis:1980-73167
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 14 Jun 2019 08:56
• Last Modified: 14 Jun 2019 08:56
• URI: https://theses.gla.ac.uk/id/eprint/73167