TABLE 1.

Characteristics of MAbs against the NS1 protein of DV1

Hybridoma cell strain	Isotype	Affinity constant (liters/mol)	Reaction with DV1 NS1 protein		IFA result from cells infected by:				Epitope groupb
			ELISAa	Western blot	DV1	DV2	DV3	DV4
M1	IgG1	2.1 × 1010	+++	+	+	−	−	−	I
M2	IgG1	6.0 × 106	++	+	+	−	−	−	III
M3	IgG1	3.0 × 109	+++	+	+	−	−	−	VI
M4	IgG1	1.4 × 1010	+++	+	+	−	−	−	II
M5	IgG1	7.7 × 109	+++	+	+	−	−	−	VI
M6	IgG2a	6.1 × 109	+++	+	+	+	+	+	IV
M7	IgG1	6.0 × 108	+++	+	+	−	−	−	VI
M8	IgG1	1.0 × 107	++	+	+	−	−	−	VI
M9	IgG1	1.0 × 108	++	+	+	−	−	−	V
M10	IgG1	1.8 × 108	+	+	+	−	−	−	V

^aThe purified recombinant DV1 NS1 protein was used as the coating antigen and was reacted with purified MAbs against the DV1 NS1 protein. The absorbance was measured at 450 nm: +, OD₄₅₀ = 0.8 to 1; ++, OD₄₅₀ = 1 to 2; +++, OD₄₅₀ > 2.

^bCompetition ELISA was performed to analyze the epitope specificity of the different MAbs. MAbs M3, M5, M7, and M8 effectively competed (≥75% inhibition) with each other, which suggests that these four MAbs recognized the same epitope. Similarly, M9 and M10 are suggested from another group, with >75% inhibition of each other's binding. MAbs M1, M2, M4, and M6 did not interfere with heterologous MAb binding (<25% inhibition), suggesting that these MAbs may recognize discrete epitopes. Therefore, these 10 MAbs were divided into six groups, each group reacting with the same epitope or sterically overlapping epitopes on the NS1 protein.