Cytopathology of cultured cells infected with herpes simplex virus
Creators: name: Haines, Patricia Jean
Publisher: name: University of British Columbia
Year: 2011

description: The cytopathology of herpes simplex virus (HSV) in H.Ep.2 and BHK-21 cells was studied using the techniques of light microscopy, immunofluorescence, electron microscopy, autoradiography and cytogenetics. Both cell types supported rapid growth cycles of HSV resulting in the production of maximum titres after 22 - 24 hours of infection. Cultures treated with 10 µg/ml ara-C or 100 µg/ml IDU at the time of infection showed a 99% decrease in infectious virus production. HSV-infected H.Ep.2 and BHK-21 cells revealed typical virus-induced inclusion bodies and a generalized disorganization of the nucleus and cytoplasm. Syncytia formation was not observed but after 24 hours of infection, nearly 100% of the cells were rounded and often detached from the glass surface. Addition of 10 µg/ml ara-C or 100 µg/ml IDU failed to prevent virus cytopathology but did cause a characteristic cytoplasmic disruption and rounding of uninfected cells. Virus-infected cells also revealed at least four separate immuno-fluorescent elements after exposure to hyperimmune serum prepared in guinea pigs. These elements included small nuclear granules, amorphous nuclear masses, diffuse cytoplasmic antigens, and intense surface fluorescence. The nuclear antigens and cytoplasmic fluorescence appeared after treatment with ara-C or IDU but the surface fluorescence was not produced in the presence of the anti-viral agents. Herpes simplex virus developed in the nucleus of infected H.Ep.2 and BHK-21 cells. The virions were enveloped at the inner lamella of the nuclear membrane and after passing into the cytoplasm, were released from the cells by a process of reverse phagocytosis. Ara-C and IDU allowed the synthesis of certain viral antigens and the development of nuclear cytopathology but completely prevented the formation of infectious HSV particles. Both drugs caused a marked distortion of the mitochondria and endoplasmic reticulum in uninfected cells. DNA synthesis in HSV-infected cells, as measured by ³H-thymidine incorporation, was almost completely inhibited by 4 hours of infection. This early inhibition of cellular DNA synthesis was followed by an immediate increase in ³H-thymidine uptake corresponding to the synthesis of viral DNA. Both cell types showed a brief stimulation of mitosis prior to the complete inhibition observed after 20 hours of infection. Cellular and viral DNA synthesis and mitosis appeared to be inhibited in virus-infected and uninfected cells treated with ara-C or IDU. Infection with HSV resulted in severe chromosomal damage to H.Ep.2 and BHK-21 cells. Chromosomal abnormalities included chromatid gaps and breaks, enhanced secondary constrictions, fragmentation, erosion, and endoreduplication, and were dependent on virus dose and time of infection. The capacity of the virus to induce chromosomal aberrations in cultured cells was UV-inactivated approximately five times less rapidly than the infectious property. Ara-C acted synergistically with the virus to produce a large number of cells with multiple chromosome breaks and also caused a significant number of abnormalities in uninfected cells. In contrast, IDU treatment resulted in few aberrations over and above those produced by HSV and little damage in uninfected cells. It was concluded that HSV was capable of producing severe morphological and genetic alterations in cultured human and hamster cells. The antiviral agents ara-C and IDU were able to completely inhibit virus multiplication but were unable to prevent any of the virus-induced cytopathic effects in vitro.