Experimental infection of ponies with equine influenza A2 (H3N8) virus strains of different pathogenicity elicits varying interferon and interleukin-6 responses.
The production of interferon (IFN), interleukin-6 (IL-6), and tumor necrosis factor (TNF) was monitored in horses during the course of influenza A2 virus infections. The effects of two virus strains, Newmarket/2/93 and Sussex/89, were compared, of which the latter is considered the more pathogenic in terms of clinical signs. Ten naive ponies were infected with influenza A/equine/Sussex/89 and 10 with influenza A/equine/Newmarket/2/93, respectively. As expected ponies infected with Sussex/89 showed the most pronounced clinical signs but there was no notable difference in viral excretion compared with Newmarket/2/93. IFN was detected in nasal secretions of all ponies infected with Sussex/89 but only in 2 ponies infected with Newmarktet/2/93. IFN was not detected in serum of any animal. IL-6 activity was detected in nasal secretions of all experimental animals from day 2 and onwards, but showed markedly higher IL-6 responses were observed in ponies infected with Sussex/89. No TNF activity was detected in any of the samples collected. In summary, equine influenza A 2 infections elicited local, and in some cases systemic, IFN and IL-6 responses in the ponies. Interestingly, there was some evidence that the duration and levels of cytokine responses may be related to the pathogenicity of the influenza strains.
Unit of Comparative Medicine and Physiology, Department of Large Animal Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden. Eva.Wattrang@kirmed.slu.se
Eva
E
Wattrang
David M
DM
Jessett
Phillip
P
Yates
Lisbeth
L
Fuxler
Duncan
D
Hannant
D000818:Animals; D002417:Cattle; D002460:Cell Line; D005260:Female; D006734:Horse Diseases / Q000276:immunology* / Q000821:virology; D006736:Horses; D053123:Influenza A Virus, H3N8 Subtype; D009980:Influenza A virus / Q000145:classification / Q000276:immunology / Q000472:pathogenicity*; D007372:Interferons / Q000096:biosynthesis*; D015850:Interleukin-6 / Q000096:biosynthesis*; D008297:Male; D051379:Mice; D009976:Orthomyxoviridae Infections / Q000276:immunology / Q000662:veterinary*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D007372:Interferons