A new assay system for evaluation of developmental immunotoxicity of chemical compounds using respiratory syncytial virus infection to offspring mice.

We evaluated the effect of 6-propyl-2-thiouracil (PTU), an anti-thyroid agent, on developmental immunity using respiratory syncytial virus (RSV) infection to offspring mice as a new risk assessment for brominated flame retardants (BFRs), because some BFRs are suspected of affecting the thyroid system. Pregnant mice were exposed to PTU in drinking water from gestation day 10 to weaning on postnatal day 21. Their offspring mice were infected intranasally with RSV. Exposure of 100ppm PTU significantly increased virus titers in the lungs of RSV-infected offspring compared with the control, and the 10ppm also elevated levels of interferon-γ, a marker of pneumonia, in the bronchoalveolar lavage fluids of offspring. Histopathological analysis revealed that PTU-exposure exacerbated pneumonia in RSV-infected offspring. Thus, exacerbation of RSV infection suggested PTU-exposure of dams elicited developmental immune disorder in the offspring. The murine RSV infection model may be useful to evaluate the developmental immunotoxicity of BFRs.