The replication of dengue virus (DENV) RNA requires at least two viral 
non-structural (NS) proteins, NS3 and NS5. To facilitate the study of the DENV 
replication complex, human monoclonal IgG that are specific for NS proteins have 
been generated and characterised. The anti-NS3 IgG, 3F8, binds a conserved 
epitope (aa526-531) in the NS3 helicase domain, and cross-reacts with NS3 from 
all four DENV serotypes and the related yellow fever virus. The anti-NS2B IgG, 
3F10, binds aa49-66 of NS2B (CF18), which forms part of the 47 aa hydrophilic 
cofactor region required for NS3 protease activity. The specificity of the IgG 
for their respective non-structural proteins has been demonstrated by 
immunofluorescence of cells infected with DENV and Western blotting. 3F8 is able 
to co-immunoprecipitate NS3 and NS5 from BHK-21 cells infected with DENV2, and 
3F10 is able to detect an interaction between recombinant NS2B(CF18)NS3 
full-length protein and the NS5 RNA-dependent RNA polymerase (RdRp) domain in an 
ELISA-based binding assay. The assay is specific and highly reproducible, with a 
clear binding curve seen when RdRp is incubated with increasing amounts of 
full-length NS3, but not the NS3 protease domain. The NS3 helicase domain 
competes with NS3 full-length for NS5 RdRp binding, with a K(d.) of 2.5μM. Since 
NS3 and NS5 are required for DENV replication, this fascile assay could be used 
to screen for non-nucleoside, allosteric inhibitors that disrupt the interaction 
between the two proteins.