TABLE 2.

Effects of anti-CD46 antibodies on GS-mediated syncytium formation and entry^b

MAb	Epitope	Block of HHV-6 functiona of:
		Syncytium formation	Expression of IE1
J4-48	SCR1	−	−
M75	SCR2	+++	+++
M160	SCR3	+++	+
OHV-2		−	−

^aBlock of CD46 function in syncytium formation and the expression of IE1. +++, syncytium formation and expression of IE1 were almost 90 to 100% inhibited by each antibody; +, almost 5 to 10% inhibited; −, not inhibited.

^bSup-T1 cells were incubated at 37°C for 60 min with each anti-CD46 MAb or OHV-2 (10 μg/ml) in RPMI 1640 with 10% FCS and then centrifuged with GS at an 0.1 MOI of at 37°C for 60 min. The cells were washed three times and cultured at 37°C for 12 h. They were fixed and stained with HE or fixed with acetone and stained with rabbit antiserum specific for HHV-6 IE1. The blocking effects were evaluated by microscopy.