Detection of initial intra-cellular functional, structural and ultra-structural changes in virus-inoculated cells: A pilot study

Mammalian cells from embryonic mouse 3 T3 and bovine trachea (EBTr) lines were incubated in in vitro-conditions. A sub-population of from the EBTr cells was inoculated with low initial infectious titers of the vaccine avipoxviral strains FK (fowl), and another - with vaccine avipoxviral strain Dessau (pigeon) (Poxviridae family). Analogically, a subpopulation from the 3 T3 cells was pre-incubated in cultural fluid from transfected by recombinant DNA-plasmid P3-X63-Ag8 mouse malignant myeloma cells and cocultivated with them, another – co-cultivated with the same malignant cells. Although cytopathogenic effect, cell inclusions and mature virions were not observed, different methods of microscopic observations revealed molecular, structural and ultra-structural differences in the inoculated cells compared to the non-inoculated. Light microscopy observations of fixed and semi-thin slides revealed membrane excrescences, changed cell shape, size and nucleus-cytoplasm ratio, as well as activated lipid and protein synthesis (particularly of collagen and elastin). Transmission electron microscopy (TEM) of ultra-thin slides indicated cytoplasmic vacuolation and granulation, changes in the cytoplasmic organelles and in the nuclear chromatin. These changes were suggested as initial markers of cell (infectious, malignant or degenerative) injury and are underlining the initial cellular protective mechanisms. As one of the manifestations of these protective systems was proposed the production of immune molecules by non-immune cells in appropriate conditions. Also, a possibility about transfer of nucleotide (DNA- and/or RNA-) fragments between cellular and viral genomes was suggested. This phenomenon is probably due to activated fusion processes on the influence of organic detergent and drastic temperature changes.