Table 2. Neutralizing and infection-enhancement activities against each of the 4 serotypes of dengue virus.
| Activity | % Prevalence of neutralizing or enhancing activity to DENV serotypes(number positive/total number) | |||
| DENV-1 | DENV-2 | DENV-3 | DENV-4 | |
| Neutralizing antibody (PRNT50 ≥1∶10) | 69 (55/80) | 60 (48/80) | 56 (45/80) | 20 (16/80) |
| DENV-1 patienta | 58 (7/12) | 67 (8/12) | 17 (2/12) | 8 (1/12) |
| DENV-3 patienta | 69 (9/13) | 69 (9/13) | 62 (8/13) | 15 (2/13) |
| Othersb | 71 (39/55) | 56 (31/55) | 64 (35/55) | 69 (38/55) |
| Enhancing activityc | 26 (21/80) | 26 (21/80) | 30 (24/80) | 73 (58/80) |
| DENV-1 patienta | 33 (4/12) | 25 (3/12) | 42 (5/12) | 75 (9/12) |
| DENV-3 patienta | 38 (5/13) | 8 (1/13) | 62 (8/13) | 85 (11/13) |
| Othersb | 22 (12/55) | 31 (17/55) | 25 (14/55) | 69 (38/55) |
a
Serum samples obtained from DENV patients. Infecting DENV serotype was determined by RT-PCR.
b
Others consist of a total of 55 serum samples from 55 non acute dengue patients. Serum samples were derived from the following categories: DENV genome and NS1 antigen negative (n = 34), and chikungunya virus (CHIKV) genome positive (n = 21).
c
Positive infection-enhancement activity was defined as fold-enhancement values greater than cut-off plus a 2 times SD (or cut-off+2SD) in the mean plaque count in the presence of human serum samples.