2,3,7,8-tetrachlorodibenzo-p-dioxin and the viral infection

Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a widespread highly toxic environmental contaminant, suppresses immune response and leads to an increased susceptibility to infectious agents. In particular, several studies have provided evidence that TCDD decreases resistance to numerous viruses. Indeed, in vivo and in vitro investigations showed that the presence of TCDD is able to interfere with the replication of both human and animal viruses, such as influenza A viruses, coxsackie virus B3, immunodeficiency virus type-1 (HIV-1), cytomegalovirus (CMV), herpes simplex II, and bovine herpesvirus 1. Moreover, TCDD could induce an exacerbation of latent infection produced by HIV-1, CMV or Epstein-Barr virus. In this review, we first describe the general effects of TCDD exposure on mammalian cells, then we focus on its influence on the viral infections. Overall, the available data support the concept that TCDD exposure may act as an additional risk factor in promoting of viral diseases.

New aspects of murine coxsackie B3 myocarditis--focus on heavy metals

The magnitude of inflammatory lesions in the hearts of coxsackie B3 (CB3)-virus infected mice can be affected by the potentially toxic heavy metals cadmium (Cd), nickel (Ni) and methyl mercury (MeHg). The infection is associated with a changed distribution, such as Cd accumulation in the spleen and kidneys. New target organs for Ni during the infection were the heart, pancreas and lungs in which inflammatory lesions were present. This increased uptake was correlated with the disturbed function of immune cells and an increased inflammatory reaction. Ni and MeHg appeared to have a direct effect on immune cells that resulted in changed natural killer cell activity and decreased mobilization of macrophages, CD4+ and CD8+ cells into the inflammatory lesions. Although MeHg increased spleen T cell activity and gamma-interferon (IFN-gamma) levels, the inflammatory lesions in the heart increased. Another detrimental effect of MeHg treatment was evident by an increased calcium and decreased zinc content in the inflamed heart, which may partly explain the more severe inflammatory lesion. The host's response, CB3 infection, changed the distribution of each metal in a specific way, a fact which may subsequently result in altered target organ toxicity and resistance to the infection.