Table. Cross-reactive antibody responses against H3 and influenza A(H1N1)pdm09 virus in 76 influenza-positive serum samples from feral swine, United States, 2011–2012*.
| Source, virus | Antigenic cluster† | No. seropositive (%)‡ |
GMT (95% CI)§ |
No. overall seropositive (%)¶ | |||
|---|---|---|---|---|---|---|---|
| HI | MN | HI | MN | ||||
| Feral swine IAV | |||||||
| A/swine/Texas/A011040013/2012(H3N2) | H3N2-β | 36 (47.4) | 36 (47.4) | 163 (40–640) | 259 (40–1,280) | 25 (32.9) | |
| Domestic swine IAV | |||||||
| A/swine/Ohio/11SW64/2009 (H3N2) | H3N2-α | 27 (35.5) | 30 (39.5) | 65 (40–160) | 121 (40–1,280) | 17 (22.4) | |
| A/swine/Iowa/12627/2009(H3N2) | H3N2-α | 30 (39.5) | 31 (40.8) | 73 (40–320) | 183 (40–1,280) | 15 (19.7) | |
| A/swine/Ohio/11SW347/2011(H3N2) | H3N2-β | 31 (40.8) | 31 (40.8) | 122 (40–640) | 112 (40–1,280) | 17 (22.4) | |
| A/swine/Iowa/6368/2012(H3N2) | H3N2-β | 26 (34.2) | 36 (47.4) | 94 (0–640) | 240 (40–1,280) | 20 (26.3) | |
| Human H3N2v IAV | |||||||
| A/IA/07/2011 | 32 (42.1) | 31 (40.8) | 109 (40–640) | 313 (40–1,280) | 21 (27.6) | ||
| Human seasonal IAV | H3N2-β | ||||||
| A/Perth/16/2009 | H3N2-β | 12 (15.8) | 5 (6.6) | 76 (40–320] | 121 (40–1,280) | 1 (1.3) | |
| A/Victoria/361/2011 | H3N2-β | 11 (14.5) | 2 (2.6) | 141 (40–640) | 226 (40–1,280) | 0 | |
| A/California/7/2009 | H3N2-β | 5 (6.6) | 3 (3.9) | 70 (40–640) | 80 (40–320) | 1 (1.3) | |
*Influenza detected by ELISA. GMT, geometric mean titer; HI, hemagglutination-inhibition; MN, microneutralization; IAV, influenza A virus. †The antigenic cluster H3N2-α and H3N2-β were defined in (5). ‡Seropositive was defined as the HI or MN titer >40. §Only serum with an HI or MN titer >40 are used to calculate the GMT. ¶Overall seroconversion was defined as both HI and MN titer >40.