The two most highly upregulated common genes from the NF-kB pathway were IP-10 (or CXCL10/IFN-inducible protein 10) and I-TAC (or CXCL11/IFN-inducible I cell a chemoattractant) ( Figure 3B) . In order to determine if this up-regulation of gene transcription lead to translation and protein release, concentrations of IP-10 and I-TAC protein in cell culture supernatant following dengue infection were determined by ELISA. In both the A549 and HepG2 infection models, dengue infected cells produced moderate, but significant (compared to heat-inactivated virus treated cells), concentrations of IP-10 ( Figure 4A ) and I-TAC ( Figure 4B ) at 72 hrs, but not at earlier time points (data not shown). We next investigated if these, or other, NF-kB induced proteins were influencing dengue virus replication. Adding dexamethasone to the HepG2 infection model to inhibit NF-kB activation [25] prevented IP-10 and I-TAC production, but had no effect on viral replication (data not shown). These results suggest that NF-kB activation, and IP-10 and I-TAC production, do not have a direct effect on viral replication and are, rather, simply part of the immune response to infection. Serum concentrations of IP-10 and I-TAC in the ten dengue fever patients described above, together with ten fever patients who did not have dengue (viral PCR negative) were also determined by ELISA. High concentrations of IP-10 ( Figure 4C ) and I-TAC ( Figure 4D) were present in the serum of dengue fever patients. There was significantly more IP-10 in the serum of the patients during the first (1-2 days after fever onset) and second (4-5 days after fever onset) visits, compared to the convalescent serum (P = 10 215 and P = 10 211 , respectively) as well as to non-dengue fever patient serum (P = 10 29 and P = 10 27 , respectively). I-TAC level was also significantly higher in first visit dengue patient serum comparing to both the convalescent (P = 10 27 ) and non-dengue fever (P = 10 26 ) patients. I-TAC levels in dengue fever patients at the second visit were significantly lower than at first visit (Fig 4D) .