An endocytic CARriage tale: Adenoviruses internalization and trafficking in neurons

In immune-competent hosts, adenoviruses (Ads) are mild pathogens that cause mainly infections of the respiratory and ocular tracks. The advent of Ad-based gene transfer vectors made the understanding of their interaction with the host cellular machinery an intensive field of research over the last decade. As studies focused primarily on epithelial-like cells, the mechanism of neuronal uptake of Ads was still missing. Using a combination of biochemical and cell biology approaches, we characterized the axonal trafficking pathway used by the canine adenovirus serotype 2 (CAV-2) to reach the neuronal soma. We showed that CAV-2 and CAR (coxsackievirus and adenovirus receptor) are entering a vesicular pathway coupled to the axonal transport machinery. The lumen of the multivalent Rab7 (+) vesicles that transport CAV-2 and CAR is, surprisingly, pH neutral. Among other issues, our study opens numerous questions concerning the neuronal function of CAR.