title: Pathogenicity and transmission of triple reassortant H3N2 swine influenza A viruses is attenuated following Turkey embryo propagation.
abstract: Genetic lineages of swine influenza A viruses (SIVs) have recently been established in Turkeys in the United States. To identify molecular determinants that are involved in virulence and transmission of SIVs to Turkeys, we sequentially passaged two triple reassortant H3N2 SIV isolates from Minnesota in ten day old specific-pathogen free (SPF) Turkey embryos and tested them in seven-day old Turkey poults. We found that SIV replication in Turkey embryos led to minimal mutations in and around the receptor binding and antigenic sites of the HA molecule, while other gene segments were unchanged. The predominant changes associated with Turkey embryo passage were A223V, V226A and T248I mutations in the receptor-binding and glycosylation sites of the HA molecule. Furthermore, Turkey embryo propagation altered receptor specificity in SIV strain 07-1145. Embryo passaged 07-1145 virus showed a decrease in α2, 6 sialic acid receptor binding compared to the wild type virus. Intranasal infection of wild type SIVs in one-week-old Turkey poults resulted in persistent diarrhea and all the infected birds seroconverted at ten days post infection. The 07-1145 wild type virus also transmitted to age matched in-contact birds introduced one-day post infection. Turkeys infected with embryo passaged viruses displayed no clinical signs and were not transmitted to in-contact poults. Our results suggest that Turkey embryo propagation attenuates recent TR SIVs for infectivity and transmission in one week old Turkeys. Our findings will have important implications in identifying molecular determinants that control the transmission and virulence of TR SIVs in Turkeys and other species.
authors.affiliation: Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States; Vajra Instruments Inc., Lincoln, NE, United States. Electronic address: shobana.feb2000@gmail.com.
authors.forename: Shobana
authors.initials: S
authors.lastname: Raghunath
authors.affiliation: Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States.
authors.forename: Raghavendra Sumanth
authors.initials: RS
authors.lastname: Pudupakam
authors.affiliation: Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States.
authors.forename: Jagadeeswaran
authors.initials: J
authors.lastname: Deventhiran
authors.affiliation: Dept of Chemical and Bioengineering, University of Nebraska, Lincoln, NE, United States.
authors.forename: Rahul
authors.initials: R
authors.lastname: Tevatia
authors.affiliation: Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States. Electronic address: tleroith@vt.edu.
authors.forename: Tanya
authors.initials: T
authors.lastname: Leroith
mesh_terms: D000818:Animals; D003967:Diarrhea / Q000662:veterinary / Q000821:virology; D005260:Female; D053122:Influenza A Virus, H3N2 Subtype / Q000472:pathogenicity* / Q000502:physiology; D008910:Minnesota; D008958:Models, Molecular; D009976:Orthomyxoviridae Infections / Q000635:transmission / Q000662:veterinary* / Q000821:virology; D010063:Ovum / Q000821:virology; D016865:Reassortant Viruses / Q000472:pathogenicity* / Q000502:physiology; D013047:Specific Pathogen-Free Organisms; D013552:Swine; D013553:Swine Diseases / Q000635:transmission / Q000821:virology*; D014422:Turkeys; D014774:Virulence
keywords: Inter species transmission; Receptor binding site and hemagglutinin; Specific pathogen free Turkey embryos; Triple reassortant Influenza A viruses