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In pigs, influenza A viruses and Mycoplasma hyopneumoniae (Mhp) are major contributors to the porcine respiratory disease complex. Pre-infection with Mhp was previously shown experimentally to exacerbate the clinical outcomes of H1N1 infection during the first week after virus inoculation. In order to better understand the interactions between these pathogens, this study aimed to assess very early responses (at 5, 24 and 48 hours) after H1N1 infection in pigs pre-infected or not with Mhp.
Clinical signs and macroscopic lung lesions were similar in both infected groups at early times post H1N1-infection and Mhp pre-infection affected neither the influenza virus replication nor the IFN-induced antiviral responses in lungs. However, it predisposed the animals to a higher inflammatory response to H1N1 infection, as revealed by the massive infiltration of neutrophils and macrophages into the lungs and the increased production of pro-inflammatory cytokines (IL-6, IL-1 and TNF-). Thus, it seems it is this marked inflammatory state that would play a role in exacerbating the clinical signs subsequent to H1N1 infection.
Céline Deblanc, Mario Delgado-Ortega, Stéphane Gorin, Mustapha Berri, Frédéric Paboeuf, Patricia Berthon, Georg Herrler, François Meurens and Gaëlle Simon; Mycoplasma Hyopneumoniae does Not Affect the Interferon-Related Anti-Viral Response but Predisposes the Pig to a Higher Level of Inflammation following Swine Influenza Virus Infection; Journal of General Virology (2016), 97, 2501�2515 DOI 10.1099/jgv.0.000573