Correlation of serostatus and viraemia levels among Indian dengue patients at the time of first diagnosis.

Background: Dengue is a public health problem worldwide. Therapeutic monoclonal antibodies (MAbs) against dengue virus (DENV) are likely to be available soon. In view of the feasibility issues pertaining to pretreatment viraemia quantitation for therapy decisions, we conducted this study for investigation of a correlation between patient serostatus (NS1/immunoglobulin M [IgM]/IgG) and viraemia levels among Indian dengue patients at the time of first diagnosis.

Methods: The study included 297 serum samples from dengue patients in Pune, India. The samples were tested for NS1, IgM and IgG (capture enzyme-linked immunosorbent assay [ELISA] for identifying secondary dengue) using Panbio ELISAs. Quantitation of viraemia was conducted using an NS1 ELISA-based 50% tissue culture infectious dose (TCID50) test in Vero cells.

Results: Viraemia was detectable only among NS1-positive patients (n = 229, range 0.5-8.3 logTCID50/ml) with a mean titre of 1.9 logTCID50/ml. Among the NS1-positive patients, DENV titres were higher in IgM-negative than IgM-positive patients (p < 0.0001) and in primary (IgG < 18 Panbio units) versus secondary (IgG > 22 Panbio units) dengue patients (p = 0.002). Virus titres were higher during the first 3 days of illness and decreased later (p = 0.005).

Conclusions: The study provides a range of infectious DENV titres in relation to serologic status among dengue patients in India. The data suggest the possibility of using serological markers (NS1/IgM) as a basis for treatment decisions.