The aim of this study was to elucidate the entry point of a H7N1 HPAIV into the CNS of chickens and to define factors determining cell tropism within the brain.
For that purpose, the chronological and topographical distribution of viral antigen, as well as the presence and distribution of IAV receptors in the CNS of infected chickens was established. A double immunostaining was employed to determine the role of the olfactory sensory neurons (OSN) in the neuropathogenesis as an initial target of IAV entry into the CNS.
Lastly, the presence of haematogenous dissemination was determined by means of viral RNA detection in the blood and cerebrospinal fluid (CSF) using a quantitative real-time reverse transcription-polymerase chain reaction (RTqPCR).
In summary, the results obtained in this study indicate that the most likely pathway for entry of the H7N1 HPAIV into the chicken brain is the haematogenous route. This is supported by the fact that brain endothelial cells, choroid plexus and ependymal cells hold large numbers of IAV receptors in their surface, which could play an important role, together with the CSF, in the entry and early dissemination of the virus. Further studies are needed to explain the exact mechanism leading to the disruption of the BBB by IAV.
Article made possible through the contribution of Aida J Chaves, NÃºria Busquets, Rosa Valle, Raquel Rivas, JÃºlia Vergara-Alert, Roser Dolz, Antonio Ramis, Ayub Darji, NatÃ lia MajÃ³ and BioMed Central.