Syrian hamsters (Mesocricetus auratus) as an upper respiratory tract model for respiratory syncytial virus infection.

Respiratory syncytial virus (RSV) is one of the leading causes of respiratory tract infection in children, immunocompromised individuals and older adults. Vaccines have recently been approved for use in adults and although further efforts to develop suitable interventions for children are ongoing, there are limited animal models for RSV infection. For preclinical efficacy testing of prophylactic and therapeutic treatments cotton rat and ferret models can be used. However, these can be expensive, difficult to source and house, and often have limitations such as insufficient virus replication in the respiratory tract and/or lack of horizontal transmission. In this study, Syrian hamsters (Mesocricetus auratus), which are relatively cheap, easy to source and house, were inoculated intranasally with a recombinant RSV-A-0594 strain expressing EGFP and using virological and pathological analyses. Viral replication was assessed and compared to viral replication in the ferret model. Although there was limited virus infection of the lower respiratory tract of Syrian hamsters, we show that a contemporary recombinant RSV-A strain replicates efficiently in the upper respiratory tract of Syrian hamsters (titers up to 4.5 Log10 TCID50/g and 12 Log10 RNA copies/g). These titers are comparable to those found in the ferret upper respiratory tract tissues post-infection with the same virus strain (up to 6.0 Log10 TCID50/g and 12 Log 10 RNA copies/g). Fluorescent regions indicating virus infection were macroscopically visible under UV-light in the nasal turbinates and histological assessment showed mucosal inflammation with necrotic cells in this tissue. In summary, Syrian hamsters generally displayed less severe systemic and pulmonary changes than ferrets, but do appear to be a promising model for upper respiratory tract infection with RSV.