TABLE 3.

Serologic reactivity to swine H1N1 viruses of pig sera collected from different swine farms in Chungbuk Province, South Koreaa

Mo rangebNo. of sera testedNo. of sera (%) positive for H1N1No. of sera (%) positive for:
Sw/Korea/CAN01/04Sw/Korea/SCJ01/09Dual infection
Apr-May555157 (28.3)34 (6.1)123 (22.2)
June-July21733 (15.2)7 (3.2)2 (1)24 (11)
Aug-Sept36947 (12.7)25 (6.8)22 (5.9)
Oct-Dec48091 (19)8 (1.7)33 (6.9)50 (10.4)
Total1,621328 (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.