Expression pattern of asialoglycoprotein receptor in human testis.

During acute or chronic hepatitis B virus (HBV) infection, the virus can invade the male reproductive system, pass through the blood-testis barrier and integrate into the germ line, resulting in abnormal spermatozoa. However, the pathway remains unclear. The asialoglycoprotein receptor (ASGR), a potential receptor for HBV, is mainly distributed in hepatocytes. We have examined the distribution of ASGR in human testis and found it in the seminiferous tubules and interstitial region but its enrichment in human testis is much lower than that in liver. By multiple immunoenzyme histochemistry staining, ASGR was precisely co-localized with vimentin (Sertoli cell marker) but not proliferating cell nuclear antigen (spermatogonial cell marker) in testis tissue. ASGR was expressed in human Leydig cells, stromal cells in the seminiferous tubules and Sertoli cells but seldom in spermatogonial cells. Therefore, ASGR could provide HBV with access to the luminal compartment of human testis. The mechanism by which HBV invades germ cells remains unknown.