Research Program Area: Health & Exposure
Topic Areas: Health Effects of Air Pollution
These investigations dealt with the effects of ozone on cellular synthesis and viral replication in vitro. A series of experiments were performed to determine the relationship between concentrations of ozone and early indications of cellular damage. The effects of ozone on viral replication when cell cultures were exposed to various concentrations of ozone prior to and during virus inoculation were also investigated. Experiments were also run to determine the effects of ozone on the ability of mouse tracheal organ explants to synthesize interferon and on the interferon molecule itself. The three cell lines used in the determination of effects of ozone on macromolecular synthesis were found to have different sensitivities to ozone. The two cell lines derived from respiratory tissue, human fetal lung (HFL) cell and bovine turbinate (BT) cells, incur decreases in RNA, DNA and protein synthesis at ozone concentrations that have no effect on the mouse L929 cells. In general there were increasing inhibition with increases in ozone concentration and exposure times. No recovery in macromolecular' synthesis was seen when cells were exposed to ozone for longer periods of time (72 and 96 hours) as would be expected if the cells were becoming "tolerant" to the effects of ozone. There were no differences in the ability of HFL cells, BT cell, and L929 cells to support the replication of WSN influenza A virus, infectious bovine rhinotraceitis virus (IBRV) and vesicular stomatitis virus (VSV), respectively, when these cell lines were exposed to ozone at concentrations ranging from 0.2 ppm to 1,O ppm for 24 and 48 hours prior to virus inoculation. No differences could be seen in virus replication when these cell lines were exposed to 1.0 and 2.0 ppm for 48 hours prior to virus inoculation, then returned to an ozone atmosphere for an additional 72 hours while viral replication was taking place. No effect on interferon synthesis or on the interferon molecule was observed when murine tracheal organ explants were exposed to 1.0 and 2. 0 ppm ozone for 24 and 48 hours prior to induction of interferon then returned to an ambient air/ozone atmosphere for an additional 96 hours while interferon synthesis was taking place. The fact that the cell lines, after ozone exposure, can support the growth of viruses would appear to indicate that these viruses are replicating efficiently in the presence of ozone insult.
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