TABLE 3.
Serologic reactivity to swine H1N1 viruses of pig sera collected from different swine farms in Chungbuk Province, South Koreaa
| Mo rangeb | No. of sera tested | No. of sera (%) positive for H1N1 | No. of sera (%) positive for: |
||
|---|---|---|---|---|---|
| Sw/Korea/CAN01/04 | Sw/Korea/SCJ01/09 | Dual infection | |||
| Apr-May | 555 | 157 (28.3) | 34 (6.1) | — | 123 (22.2) |
| June-July | 217 | 33 (15.2) | 7 (3.2) | 2 (1) | 24 (11) |
| Aug-Sept | 369 | 47 (12.7) | — | 25 (6.8) | 22 (5.9) |
| Oct-Dec | 480 | 91 (19) | 8 (1.7) | 33 (6.9) | 50 (10.4) |
| Total | 1,621 | 328 (20.2) | 49 (3) | 60 (3.7) | 219 (13.5) |
a
Hemagglutination inhibition (HI) assays were performed as previously described (21). Pig sera were tested for the presence of antibody against a 2004 Korean H1N1 swine isolate (29) or a swine pandemic (H1N1) 2009 influenza virus isolate (Sw/Korea/SCJ01/09) using 0.5% turkey RBC. Limit of detection for the HI assays was set to <20 HI units. —, no cross-reactivity.
b
Apr, April; Aug, August; Sept, September; Oct, October; Dec, December.