TABLE 1.

Estimated binding affinities of soluble forms of the Tvb receptors for ASLV envelope glycoproteins expressed on the surfaces of L15 CEFs

Cells	Apparent KD (nM)a
	sTvbS1-mIgG	sTvbS1C125S-mIgG	sTvbS3-mIgG
L15/ASLV(B)	0.07 ± 0.01	1.27 ± 0.65	0.15 ± 0.03
L15/ASLV(D)	0.23 ± 0.08	8.77 ± 3.17	0.50 ± 0.14
L15/ASLV(E)	0.17 ± 0.05	≫1,000b	NDBc

^aApparent K_D values were estimated by fitting data via nonlinear least squares to log logistic growth curve function as described in Materials and Methods. Each result is the average and standard deviation from three experiments.

^bBinding of the sTvb^S1C125S-mIgG receptor was detectable but not sufficient to calculate a reliable apparent K_D (Fig. 3).

^cNDB, no detectable binding.