Location: Virus and Prion ResearchTitle: Characterization of a novel human seasonal H3 influenza A virus spillover endemic in US swine
|SHARMA, ADITI - IOWA STATE UNIVERSITY|
|ZELLER, MICHAEL - IOWA STATE UNIVERSITY|
|HARMON, KAREN - IOWA STATE UNIVERSITY|
|LI, GANWU - IOWA STATE UNIVERSITY|
|ZHANG, JIANQIANG - IOWA STATE UNIVERSITY|
|GAUGER, PHILLIP - IOWA STATE UNIVERSITY|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/18/2019
Publication Date: 11/4/2019
Citation: Sharma, A., Zeller, M.A., Anderson, T.K., Vincent, A.L., Harmon, K., Li, G., Zhang, J., Gauger, P.C. 2019. Characterization of a novel human seasonal H3 influenza A virus spillover endemic in US swine [abstract]. Conference of Research Workers in Animal Diseases . Abstract No. P178.
Technical Abstract: Objective: A reverse-zoonosis transmission of human-seasonal H3 IAV from humans into swine was detected in Oklahoma in March, 2017 and has demonstrated sustained circulation within the U.S. swine population. The objective of this study was to genetically characterize the hemagglutinin (HA) and neuraminidase (NA) genes of 46 viruses and whole genome sequences of 13 strains. Methods: Publicly available human-seasonal and swine H3 data were obtained from IRD and randomly sampled. A time-scaled Bayesian analysis was used to calculate the time to the most recent common human H3 ancestor. HA glycosylation was analyzed using the Nglyc online tool. Results: Spatial dissemination of genetically similar H3 HA across the central U.S. was observed with 1 detection in Ohio, 3 in Illinois, 5 in Iowa, 11 in Arkansas, 12 in Indiana, 12 in Oklahoma and 2 from unknown states. Spillover of this lineage from humans into swine occurred between approximately August 2016 and September 2016. Whole genome sequencing revealed that the N2 neuraminidase (NA) was also of human-seasonal origin with the matrix gene of H1N1pdm09 origin and all other internal genes of triple reassortant (TRIG) origin. Pairwise comparison between the first detected swine HA gene and the most similar human seasonal H3 revealed 99.9% similarity. Evaluation of N-glycosylation sites revealed that after 2017 the HA protein lost a predicted glycosylation at position 133 (H3 numbering) within the antigenic site A and the 130-loop of the receptor binding site. Following spillover, early swine viruses had an antigenic motif of STHNYK (amino acid position 145, 155, 156, 158, 159 and 189) which was identical with the closest human seasonal virus. STHNYK was the primary motif post-introduction, whereas STHNYN was predominant after April 2017. Conclusion: We report an emergence of the second sustained human seasonal H3 IAV spillover into swine in the 2010 decade (designated “2010.2”). These data confirm that human IAV are repeatedly introduced into swine and become established in the population, contributing to the genetic and antigenic diversity of IAV circulating in swine.