Apoptotic events induced by human rhinovirus infection.

HeLa and 16HBE14o(-) bronchial epithelium cells infected with human rhinovirus serotype 14 (HRV14) were found to exhibit typical apoptotic morphological alterations, such as cell contraction and nuclear condensation. These events coincided with high-molecular-weight DNA fragmentation, activation of caspase-9 and caspase-3 and poly(ADP-ribose) polymerase cleavage. Caspase activation was preceded by cytochrome c translocation from the mitochondria to the cytoplasm, indicating that apoptosis caused by HRV14 infection was triggered predominantly via the mitochondrial pathway. Apoptosis did not affect HRV14 replication per se, but it facilitated the release of newly formed virus from cells. As apoptosis was fully induced at the time of maximal accumulation of progeny HRV14, it is postulated that apoptosis contributed to the destabilization of the cell and facilitated viral progeny release.

Antiviral effects of pyrrolidine dithiocarbamate on human rhinoviruses.

Human rhinoviruses (HRVs) are the predominant cause of the common cold. The frequency of HRV infections in industrial countries and the lack of effective therapeutical treatment underline the importance of research for new antiviral substances. As viral infections are often accompanied by the generation of oxidative stress inside the infected cells, several redox-active substances were tested as potential antivirals. In the course of these studies it was discovered that pyrrolidine dithiocarbamate (PDTC) is an extremely potent compound against HRV and poliovirus infection in cell culture. Besides the ability to dramatically reduce HRV production by interfering with viral protein expression, PDTC promotes cell survival and abolishes cytopathic effects in infected cells. PDTC also protects cells against poliovirus infection. These effects were highly specific, as several other antioxidants (vitamin C, Trolox, 2-mercaptoethanol, and N-acetyl-L-cysteine) are inactive against HRV infection. Synthesis of HRV proteins and cleavage of eucaryotic initiation factor 4G responsible for host cell shutoff of cellular protein synthesis are severely inhibited in the presence of PDTC.