title: Enhanced replication of swine influenza viruses in dexamethasone-treated juvenile and layer turkeys.
abstract: Frequent transmission of swine influenza viruses (SIVs) to turkeys has been reported since 1980s. Experimental studies also showed that SIVs can infect turkeys with varying replication and transmission efficiency depending on the strain. However, host factors involved in infection/replication efficiency remain unclear. To investigate whether the immune status of turkeys might play a role in the susceptibility of turkeys to SIVs, we studied the replication efficiency of two recent SIVs (human-like H1N2 and triple reassortant (TR) H3N2) in dexamethasone-treated turkeys. The viruses were inoculated intranasally in both dexamethasone-treated and untreated control juvenile and layer turkeys. Amount of virus shedding was monitored at 2, 4, and 7 days post inoculation (DPI). Additionally, passage of both viruses was attempted in dexamethasone-treated 4-week-old turkeys. In both juvenile and layer turkeys, we were able to detect human-like H1N2 SIV only from dexamethasone-treated turkeys and no virus was detected in untreated birds. The virus shedding of the TR H3N2 SIV was also consistently higher (≈ 1 Log(10)EID(50)/ml) in dexamethasone-treated birds in both tracheal and cloacal swabs compared to untreated birds. Virus passage in dexamethasone-treated turkeys was successful up to the second passage and no virus was recovered from the third passage. These results show that potential immunosuppression due to dexamethasone treatment may enhance the transmission and adaptation of SIVs in turkeys through enhancement of virus replication, prolonged virus shedding, and possible decrease of infectious dose required to initiate infection.
authors.affiliation: Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, United States; Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, United States.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Ali
authors.affiliation: Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, United States; Department of Poultry Diseases, Menoufia University, Menoufia, Egypt.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Ibrahim
authors.affiliation: Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, United States; Department of Poultry Diseases, Mansoura University, Mansoura, Egypt.
authors.forename: Abdelfattah H
authors.initials: AH
authors.lastname: Eladl
authors.affiliation: Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, United States; Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, United States.
authors.forename: Yehia M
authors.initials: YM
authors.lastname: Saif
authors.affiliation: Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, United States; Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, United States. Electronic address: lee.2854@osu.edu.
authors.forename: Chang-Won
authors.initials: CW
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology*; D004285:Dogs; D006801:Humans; D057221:Influenza A Virus, H1N2 Subtype / Q000502:physiology*; D053122:Influenza A Virus, H3N2 Subtype / Q000502:physiology*; D005585:Influenza in Birds / Q000821:virology*; D061985:Madin Darby Canine Kidney Cells; D011201:Poultry Diseases / Q000821:virology*; D034421:Sus scrofa; D013552:Swine; D014422:Turkeys; D014779:Virus Replication / Q000187:drug effects*; D017201:Virus Shedding
chemical_list: D003907:Dexamethasone