Dynamic changes of dengue viral loads and IgM antibody and their relationships with disease severity / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate the dynamic changes of dengue viral loads and IgM antibody in patients with dengue fever ( DF) and to analyze their relationships with disease severity. Methods A to-tal of 1 508 serum samples were collected from 1 140 hospitalized patients including 1 050 mild cases and 90 severe cases within 10 days after the onset of DF in Guangzhou in 2014. The viral loads were determined by using fluorescence quantitative RT-PCR. ELISA was performed to measure the dengue virus ( DENV)-spe-cific IgM antibody. Results In general, the DENV viral loads in patients declined gradually from 108 copies/ml on day 1 to 103 copies/ml on day 10 after the onset of DF. The viral loads in severe cases were significantly higher than those in mild cases on days 5 to 7 (P<0. 05). The positive rates of DENV RNA in serum samples also decreased with the disease progression from 100% on day 1 to 40% on day 10. Com-pared with the mild cases, the patients with severe DF showed higher positive rates of DENV RNA on day 6 and day 8 (P<0. 05). The DENV-specific IgM antibody could be detected on day 2 and the secretion of IgM antibody increased gradually with the disease progression. The levels of IgM antibody in mild cases were sig-nificantly higher than those in severe cases (P<0. 001). The positive rates of IgM antibody in patients in-creased form 8% on day 2 to 95% on day 6. Higher positive rates of IgM antibody were detected in mild ca-ses on days 5 and 6 as compared with those in patients with severe DF (P<0. 05). Conclusion High viral load and low level of IgM antibody during the fastigium of DF were closely associated with the disease severity.