Infection of Chinese hamster ovary cells by pseudorabies virus

Chinese hamster ovary (CHO) cells have recently been used for identificatio n of receptors for several alphaherpesviruses, including pseudorabies virus (PrV) (R. J. Geraghty, C. Krummenacher, G. H. Cohen, R J. Eisenberg, and P . G. Spear, Science 280:1618-1620, 1998). The experiments were based on the fact that CHO cells are inefficient target cells for PrV. However, a detai led analysis of the interaction between PrV and CHO wild-type and recombina nt PrV-receptor bearing cells has not been performed. We show here that PrV has a growth defect on CHO cells which leads to a ca. 100-fold reduction i n plating efficiency, strongly delayed penetration kinetics, and a 10(4)-fo ld reduction in one-step growth. Entry of PrV into CHO cells is significant ly delayed but is not affected by inhibitors of endocytosis, suggesting tha t the mechanism of penetration resembles that on permissive cells. The defe cts in plating efficiency and penetration could be corrected by expression of herpesvirus entry mediators B (HveB), HveC, or HveD, with HveC being the most effective. However, the defects in one-step growth and plaque formati on were not corrected by expression of PrV receptors, indicating an additio nal restriction in viral replication after entry. Surprisingly, PrV infecti on of CHO cells was sensitive to neutralization by a gB-specific monoclonal antibody, which does not inhibit PrV infection of other host cells. Moreov er, the same monoclonal antibody neutralized PrV infectivity on cells displ aying the interference phenomenon by overexpression;of go and subsequent in tracellular sequestration of go receptors. Thus, absence of go receptors on two different host cells leads to an increased sensitivity of PrV toward g B neutralization. We hypothesize that this is due to the increased requirem ent for interaction of gB with a cellular surface protein in the absence of the gD-gD receptor interaction. As expected, CHO cells are as susceptible as other host cells to infection by PrV gD(-) Pass, an infectious go-negati ve PrV mutant. However, PrV gD(-) Pass was also not able to form plaques on CHO cells.