Location: Virus and Prion ResearchTitle: Detection and characterization of an H4N6 avian-lineage influenza A virus in pigs in the Midwestern United States
|GAUGER, PHILLIP - Iowa State University
|WALIA, RASNA - Orise Fellow
|RAJAO, DANIELA - Orise Fellow
|ZHANG, JIANQIANG - Iowa State University
|HARMON, KAREN - Iowa State University
|KILLIAN, MARY LEA - Animal And Plant Health Inspection Service (APHIS)
Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2017
Publication Date: 11/1/2017
Citation: Abente, E.J., Gauger, P.C., Walia, R.R., Rajao, D.S., Zhang, J., Harmon, K.M., Killian, M., Vincent, A.L. 2017. Detection and characterization of an H4N6 avian-lineage influenza A virus in pigs in the midwestern United States. Virology. 511:56-65. https://doi.org/10.1016/j.virol.2017.08.021.
Interpretive Summary: There are three subtypes of influenza A virus (IAV) found in swine globally: H1N1, H1N2 and H3N2. In addition to pigs, IAV is an important pathogen in humans and birds and other host species, and infection with viruses between hosts plays an important role in the evolution of this virus. IAV strains that are adapted to one type of host sporadically infect different host species and may lead to an outbreak in the new host population. In December of 2015 a subtype of IAV not normally found in pigs but common in wild ducks, H4N6, was detected in a sick pig. In an experimental challenge study, the H4N6 showed limited ability to infect the lungs of pigs, no virus was detected in the nasal cavity, and there was no evidence of spread from pig-to-pig. The experimental results suggest the H4N6 was not likely to be successful in pigs, and follow up testing on the pig farm indicate that the avian H4N6 was not sustained and quickly died out. Although this avian H4N6 had a low risk of infecting and spreading in pigs, these types of studies are critical for evaluating emerging IAV in swine that may impact swine producers.
Technical Abstract: H4Nx viruses were reported in swine in Canada and China, but had not been recognized in swine in the USA. In late 2015, an avian-origin H4N6 influenza A virus was isolated from pigs in the United States during a routine diagnostic investigation of clinical respiratory disease in the herd. Serological analysis from additional pigs at the farm and other pigs within the swine production system indicated that the virus did not efficiently transmit from pig to pig and the mode of transmission to swine could not be determined. The isolate was characterized at the molecular level and the pathogenesis and transmission was experimentally evaluated in pigs. Although the virus replicated in the lungs of pigs and caused mild pulmonary lesions, there was no evidence of replication in the upper respiratory tract or transmission to indirect contacts, supporting the findings on the farm.