Avian influenza virus subtype H9N2 (H9N2) and Chlamydia psittaci (C. psittaci) are frequently isolated in chickens with respiratory disease. However, their roles in co-infection remain unclear. We tested the hypothesis that C. psittaci enhances H9N2 infection through suppression of host immunity. Thus, 10-day-old SPF chickens were inoculated intra-tracheally with a high or low virulence C. psittaci strain, and were simultaneously vaccinated against Newcastle disease virus (NDV). Significant decreases in body weight, NDV antibodies and immune organ indices occurred in birds with the virulent C. psittaci infection, while the ratio of CD4+/CD8+ T cells increased significantly compared to that of the lower virulence strain. A second group of birds were inoculated with C. psittaci and H9N2 simultaneously (C. psittaci+H9N2), C. psittaci 3 days prior to H9N2 (C. psittaci/H9N2), or 3 days after H9N2 (H9N2/C. psittaci), C. psittaci or H9N2 alone. Survival rates were 65%, 80% and 90% in the C. psittaci/H9N2, C. psittaci+H9N2 and H9N2/C. psittaci groups, respectively and respiratory clinical signs, lower expression of pro-inflammatory cytokines and higher pathogen loads were found in both C. psittaci/H9N2 and C. psittaci+H9N2 groups. Hence, virulent C. psittaci infection suppresses immune response by inhibiting humoral responses and altering Th1/Th2 balance, increasing mortality in H9N2 infected birds.

The obligate intracellular Gram-negative bacterium Chlamydia psittaci causes systemic disease in psittacine birds, domestic poultry, and wild fowl. Importantly, C. psittaci may cause pneumonia, encephalitis, endocarditis, and even death in humans. The potential of pigeons as a source of human psittacosis is supported worldwide by relatively high seroconversion rates in the birds. This study reports the whole-genome sequencing of C. psittaci strain HJ, isolated from meat pigeons suffering from severe pneumonia and high mortality in 2013 in Hebei, China.

Purpose To evaluate the efficacy of using optokinetic nystagmus (OKN) suppression and induction method as an objective measurement of visual acuity at near and distance. Methods Eighty‐three eyes of 83 patients were examined from December 2007 to February 2008. The visual stimuli were presented on a 17‐inch monitor screen located 40cm from subject for measuring visual acuity at near and on a 127‐inch projector screen located 3m for visual acuity at distance. Eye movement were recorded by infrared oculography and analyzed. The correlation between objective visual acuities at near and distance and subjective visual acuities at near and distance were evaluated. And the reproducibility of objective visual acuity measurement was also investigated. Results Linear regression identified that objective visual acuities measured by using OKN suppression and induction methods were found to be correlated with subjective visual acuities(r2; induction method at near: suppression method at near: induction method at distance: suppression method at distance = 0.641:0.685:0.566:0.724, P<.05). And the objective visual acuity measurement showed high reproducibility(intraclass correlation; induction method at near: suppression method at near: induction method at distance: suppression method at distance = 0.963:0.994:0.945:0.988, P<.05). The suppression method is useful in patient with visual acuities better than 20/120 while the induction method is useful in patient with visual acuities worse than 20/120. Conclusion The objective near and distance visual acuities measured by presenting optokinetic stimuli on 17‐inch monitor screen located 40cm from subject and on a 127‐inch projector screen located 3m were highly correlated with subjective near and distance visual acuities.

Purpose To determine the role of T cells and natural killer (NK) cells in mediating corneal xenograft rejection of a pig‐to‐mouse model. Methods Pig corneas were orthotopically transplanted to C57BL/6, Balb/c‐nu and CB.17 SCID mice with or without NK depletion. NK cells were depleted by an intraperitoneal injection of anti‐NK1.1 mAb three days before and one day after transplantation. Graft survival was clinically assessed by slit‐lamp microscopy, and median survival times (MST) were calculated. The rejected grafts were histologically evaluated. Results The pig corneal xenografts were acutely rejected by C57BL/6 mice (MST 7.00±0.61 days), while Balb/c‐nu and CB.17 SCID mice rejected pig corneas in more delayed fashion (MST 14.00±0.77 and 15.00±0.58 days, respectively). NK depletion failed to a further prolongation of the pig corneal xenograft survival in Balb/c‐nu mice. The rejected grafts in C57BL/6 mice were heavily infiltrated with inflammatory cells, the majority of which were macrophages. Many CD4+ T cells were observed, but either CD8+ T cells or NK cells were rarely found. In contrast, the grafts in Balb/c‐nu mice had markedly decreased inflammatory infiltration with small amounts of macrophages and CD4+ T cells, and the infiltration was further reduced in CB.17 SCID mice. Conclusion Acute rejection of the pig corneal xenografts in mice is not solely a consequence of an adaptive immunity although CD4+ T cells play an important role in the graft rejection. Other innate immune effectors than NK cells seem to be involved in the rejection of a pig‐to‐mouse corneal xenotransplantation.

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