The development of a specific inflammation in mice that had been infected by two influenza virus strains, A/chicken/Kurgan/5/2005 (H5N1) and A/Hamburg/2009 MA (H1N1), was studied. We investigated the effect of a non-toxic lipopolysaccharide from Rhodobacter capsulatus PG on the survival and body weight of the mice, production of IgG antibodies, and the induction of proand anti-inflammatory cytokines in blood serum. The administration of the R. capsulatus PG lipopolysaccharide was shown to induce interferon-â synthesis, both in healthy and influenza A virus-infected mice, and to promote production of antiviral antibodies in the blood of the influenza-infected animals. © 2019 National Research University Higher School of Economics.