Role of a Novel Protein, CAR-like Soluble Protein (CLSP), in Adenovirus Infection

Abstract

Coxsackievirus and adenovirus receptor (CAR) is a member of the immunoglobulin superfamily and a component of epithelial tight junction. CAR also functions as a primary receptor for coxsackievirus B and adenovirus (Ad) infection. Recently, we have identified a novel protein, CAR-like soluble protein (CLSP), which is closely related to CAR. Mouse CLSP (mCLSP) was composed of 390 amino acids, including three Ig domains, and showed strong homology to the IgV domain of CAR. Interestingly, mCLSP lacks a transmembrane domain, indicating that this is a soluble protein. When mCLSP cDNA was introduced into CAR-positive cells, the infection with Ad vector was severely inhibited. On the other hand, mCLSP promoted the infection with Ad vector in CAR-negative cells. Furthermore, recombinant CLSP directly bound to Ad and inhibited the Ad vector-mediated transduction in CAR-positive cells. Computational analysis for a genome database showed that the CLSP gene is rodent-specific, and that human and bovine lack this gene. Here, I discuss the function of CLSP for Ad infection.