for productive infection. Additional research using the technique Knockout Cell Line has shown that although GB4 does not have the direct entry receptor for B19V, it plays a post-entry role in productive infection.

Globoside 4 (Gb4) are a type of SSEA, stage-specific embryonic antigen, that is present in cellular development and tumorous tissues without the mechanism of Gb4 being completely known. However a study has shown Gb4 directly activates the epidermal