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Volume 20, Number 5—May 2014

Influenza A Subtype H3 Viruses in Feral Swine, United States, 2011–2012

Zhixin Feng, John A. Baroch, Li-Ping Long, Yifei Xu, Frederick L. Cunningham, Kerri Pedersen, Mark W. Lutman, Brandon S. Schmit, Andrew S. Bowman, Thomas J. DeLiberto, and Xiu-Feng WanComments to Author 
Author affiliations: Mississippi State University, Mississippi State, Mississippi, USA (Z. Feng, L.-P. Long, Y. Xu, X.-F. Wan); Jiangsu Academy of Agricultural Sciences, Nanjing, China (Z. Feng); Animal and Plant Health Inspection Service of the US Department of Agriculture, Fort Collins, Colorado, USA (J.A. Baroch, K. Pedersen, M.W. Lutman, B.S. Schmit, T.J. DeLiberto); Animal and Plant Health Inspection Service of the US Department of Agriculture, Mississippi State (F.L. Cunningham); The Ohio State University, Columbus, Ohio, USA (A.S. Bowman)

Main Article


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
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.

Main Article

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The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.