Cellular Prion Protein Combined with Galectin-3 and -6 Affects the Infectivity Titer of an Endogenous Retrovirus Assayed in Hippocampal Neuronal Cells

Prion diseases are infectious and fatal neurodegenerative diseases which require the cellular prion protein, PrP(C), for development of diseases. The current study shows that the PrP(C) augments infectivity and plaque formation of a mouse endogenous retrovirus, MuLV. We have established four neuronal cell lines expressing mouse PrP(C), PrP(+/+); two express wild type PrP(C) (MoPrP(wild)) and the other two express mutant PrP(C) (MoPrP(mut)). Infection of neuronal cells from various PrP(+/+) and PrP(-/-) (MoPrP(KO)) lines with MuLV yielded at least three times as many plaques in PrP(+/+) than in PrP(-/-). Furthermore, among the four PrP(+/+) lines, one mutant line, P101L, had at least 2.5 times as many plaques as the other three PrP(+/+) lines. Plaques in P101L were four times larger than those in other PrP(+/+) lines. Colocalization of PrP and CAgag was seen in MuLV-infected PrP(+/+) cells. In the PrP-MuLV interaction, the involvement of galectin-3 and -6 was observed by immunoprecipitation with antibody to PrP(C). These results suggest that PrP(C) combined with galectin-3 and -6 can act as a receptor for MuLV. P101L, the disease form of mutant PrP(C) results suggest the genetic mutant form of PrP(C) may be more susceptible to viral infection.