Pathogenesis, humoral immune responses and transmission between co-housed animals in a ferret model of human RSV infection.

Small animal models have been used to obtain many insights regarding the pathogenesis and immune responses induced following infection with human respiratory syncytial virus (hRSV). Amongst those described to date, infections in cotton rats, mice, guinea pigs, chinchillas and Syrian hamsters with hRSV strains Long and/or A2 have been well characterised, although clinical isolates have also been examined. Ferrets are also susceptible to hRSV infection but the pathogenesis and immune responses elicited following infection have not been well characterised. Herein, we describe the infection of adult ferrets with hRSV Long or A2 via the intranasal route and characterised virus replication, as well as cytokine induction, in the upper and lower airways. Virus replication and cytokine induction during the acute phase of infection (days 0-15 post-infection) were similar between the two strains and both elicited high levels of F glycoprotein-specific binding and neutralising antibodies following virus clearance (days 16-22 post-infection). Importantly, we demonstrate transmission from experimentally infected donor ferrets to co-housed naïve recipients and have characterised virus replication and cytokine induction in the upper airways of infected contact animals. Together, these studies provide a direct comparison of the pathogenesis of hRSV Long and A2 in ferrets and highlight the potential of this animal model to study serological responses and examine interventions that limit transmission of hRSV. IMPORTANCE Ferrets have been widely used to study pathogenesis, immunity and transmission following human influenza virus infections, however far less is known regarding the utility of the ferret model to study hRSV infections. Following intranasal (IN) infection of adult ferrets with the well characterised Long or A2 strains of hRSV, we report virus replication and cytokine induction in the upper and lower airways, as well as the development of virus-specific humoral responses. Importantly, we demonstrate transmission of hRSV from experimentally infected donor ferrets to co-housed naïve recipients. Together, these findings significantly enhance our understanding of the utility of the ferret as a small animal model to investigate aspects of hRSV pathogenesis and immunity.