To test their function as Echo7 receptor, we infected CD55-KO cells or CD55-rescued cells with Echo7 and found that CD55-KO cells are resistant to Echo7 infection, while CD55 KO cells complemented with either CD55/GPI or CD55/TM rescued Echo7 infection (Fig 2E and 2F), demonstrating that CD55/TM, like wild type CD55, can function as an Echo7 entry receptor. Here, CD55 is linked to infection.