Future treatments may involve customizing treatment to the virus pathotype.

We are currently facing a global threat caused by a highly pathogenic avian H5N1 influenza virus (hpH5N1). Death occurs in 48 h in infected chickens, suggesting that they fail to eliminate the virus. Little is known about the immune response in chickens after hpH5N1 infection, or how the virus is evolving to modify and evade host protective responses. Therefore, to better understand the chicken immune response following hpH5N1 infection, we set up an experimental infection of chickens with an hpH5N1 strain, and quantified the mRNA expression of several cytokines and antiviral proteins at different time points post-infection. We show here that a weak host immune response is observed in vivo, in spite of the induction of IL-6, myxovirus resistance protein (Mx), and protein kinase R (PKR). This weak immune response, probably due in part to the absence of type I interferon, was not sufficient to counteract the hpH5N1 virus and protect the chicken from death.

To assess the susceptibility of pigeons (Columba livia) to infection with H5N1 high pathogenicity avian influenza virus (HPAIV), four groups of 1-yr-old and 4-wk-old racing pigeons (10 birds in each group) were inoculated oculonasally with 106 50% egg infectious dose (EID50) of A/crested eagle/Belgium/01/2004 (clade 1) or A/swan/Poland/305-135V08/2006 (clade 2.2). Contact specific-pathogen-free (SPF) chickens were kept in the same isolators as young pigeons (two chickens per group). At 3, 5, 7, 10, and 14 days postinfection (PI) two pigeons from each infected group were selected randomly, and oropharyngeal and cloacal swabs (pigeons and contact chickens) as well as a number of internal organs (pigeons) were collected for viral RNA detection in real-time reverse transcription PCR (RRT-PCR) and histopathology. At the end of the experiment (14 days PI) blood samples from two pigeons in each group and from contact SPF chickens were also collected, and sera were tested using hemagglutination inhibition (HI) test and blocking enzyme-linked immunosorbent assay (bELISA). During the observation period all pigeons remained clinically healthy, and no gross lesions were observed in any of the infected groups. SPF contact chickens were also healthy and negative in RRT-PCR and HI tests. However, the clade 1 H5N1 virus produced more sustained infection manifested by the presence of histopathologic changes (consisting mainly of mild to moderate hemorrhagic and inflammatory lesions), prolonged persistence of viral RNA (detectable between 3 and 10 days PI) in a variety of tissues of both adult and juvenile birds (with highest RNA load in lungs and brain) as well as slight viral shedding from the trachea and cloaca, but without transmission to SPF contact chickens. Additionally, two clade 1-infected adult pigeons sacrificed at the end of experiment showed seroconversion in bELISA and HI test (using homologous virus as antigen). The viral RNA was found only at day 3 PI in one adult pigeon inoculated with dade 2.2 H5N1 virus, but neither microscopic lesions nor seroconversion were found in any other tested birds inoculated with A/swan/Poland/305-135V08/2006. Our results support the observations that pigeons are resistant to H5N1 HPAIV (no deaths or clinical signs), but there may be clade-dependent differences in the pathogenic potentials of H5N1 HPAIV of Asian origin.

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The anti-inflammatory properties of glucocorticoids are well known but their protective effects exerted with a low potency against heavy metals-induced pulmonary inflammation remain unclear. In this study, a model of acute pulmonary inflammation induced by a single inhalation of cadmium in male Sprague-Dawley rats was used to investigate whether formoterol can improve the anti-inflammatory effects of budesonide. The cadmium-related inflammatory responses, including matrix metalloproteinase-9 (MMP-9) activity, were evaluated. Compared to the values obtained in rats exposed to cadmium, pretreatment of inhaled budesonide (0.5 mg/15 ml) elicited a significant decrease in total cell and neutrophil counts in bronchoalveolar lavage fluid (BALF) associated with a significant reduction of MMP-9 activity which was highly correlated with the number of inflammatory cells in BALF. Additionally, cadmium-induced lung injuries characterized by inflammatory cell infiltration within alveoli and the interstitium were attenuated by the pre-treatment of budesonide. Though the low concentration of budesonide (0.25 mg/15 ml) exerted a very limited inhibitory effects in the present rat model, its combination with an inefficient concentration of formoterol (0.5 mg/30 ml) showed an enhanced inhibitory effect on neutrophil and total cell counts as well as on the histological lung injuries associated with a potentiation of inhibition on the MMP-9 activity. In conclusion, high concentration of budesonide alone could partially protect the lungs against cadmium exposure induced-acute neutrophilic pulmonary inflammation via the inhibition of MMP-9 activity. The combination with formoterol could enhance the protective effects of both drugs, suggesting a new therapeutic strategy for the treatment of heavy metals-induced lung diseases.