Respiratory Syncytial Virus Infection Modeled in Aging Cotton Rats (Sigmodon hispidus) and Mice (Mus musculus)

Serious infection with respiratory syncytial virus (RSV) is associated with high risk in infants, children, and elderly. There is currently no approved vaccine against RSV infection, and the only available prevention is immunoprophylaxis utilized in high-risk infants, leaving the elderly without many options. In the elderly, the chronic low-grade inflammatory state of the body can play a significant role during infection. The cotton rat and mouse have emerged as the preferred small animal models to study RSV infection in the elderly. These animal models of aging have shown an age-dependent time course for clearance of virus correlating with a significantly diminished cytotoxic T lymphocyte and humoral immune response in old animals compared to adult animals. In addition, protection through vaccination is reduced in aging rodents. These results mirror the findings in humans. In mice and cotton rats, treatment with ibuprofen, a nonselective nonsteroidal anti-inflammatory drug (NSAID), to decrease the chronic low-grade inflammation of the elderly immune system has proven successful in restoring the function of cytotoxic lymphocytes. While more research is required, these treatment types promise a beneficial effect in addition to a putative vaccine. Choosing an appropriate animal model to study RSV infection in the aging immune system is essential to benefit the growing population of elderly in the world. This review focuses on the current research of RSV infection in the cotton rat and mouse as model systems for an aging immune system.