Identification of CD164 as an essential entry receptor for divergent adeno-associated viruses

Recombinant adeno-associated viruses (rAAVs) are widely used for in vivo gene delivery. While KIAA0319L, known as AAV receptor (AAVR), is essential for the transduction of multiserotype AAVs, it is dispensable for AAV4-related (Clade G) AAVs. We conducted a genome-wide CRISPR/Cas9 screen and identified CD164, a type I transmembrane sialomucin, as an essential entry receptor for Clade G AAVs. Ablation of CD164 expression substantially impaired both entry and transduction of Clade G AAVs. CD164-targeting antibodies and soluble CD164 ectodomain effectively blocked transduction. AAV4 capsids colocalized with CD164 at the plasma membrane and in endosomal compartments. In vitro, CD164 interacted with AAV4 or AAVrh32.33 capsids at high affinity. Importantly, systemic administration of rAAV4 or rAAVrh32.33 in <i>CD164</i> knockout (KO) mice resulted in nearly complete loss of transgene expression. These findings establish CD164 as an essential entry receptor for Clade G AAV vectors and uncover a distinct AAVR-independent mechanism of AAV tropism.