Pathogenicity and Immune Responses of Aspergillus fumigatus Infection in Chickens

Zhimin Cheng; Mengxuan Li; Yao Wang; Tongjie Chai; Yumei Cai; Ning Li

doi:10.3389/fvets.2020.00143

Pathogenicity and Immune Responses of Aspergillus fumigatus Infection in Chickens

Front Vet Sci. 2020 Mar 11:7:143. doi: 10.3389/fvets.2020.00143. eCollection 2020.

Authors

Zhimin Cheng^{1

2

3

4}, Mengxuan Li^{1

2

3

4}, Yao Wang^{1

2

3

4}, Tongjie Chai^{1

2

3

4}, Yumei Cai^{1

2

3

4}, Ning Li^{1

2

3

4}

Affiliations

¹ College of Animal Science and Technology, Shandong Agricultural University, Taian, China.
² Sino-German Cooperative Research Centre for Zoonosis of Animal Origin Shandong Province, College of Animal Science and Technology, Shandong Agricultural University, Taian, China.
³ Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, Taian, China.
⁴ Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Shandong Agricultural University, Taian, China.

Abstract

Aspergillus fumigatus is a ubiquitous pathogen in poultry farms, causing aspergillosis in chickens. To study the pathogenicity of A. fumigatus, 14-days-old chickens were infected with fungal conidia (2 × 10⁷ CFU/mL) via thoracic intra-air sacs inoculation. The clinical symptoms, gross and histopathological lesions, and fungal load in the lungs were examined. Additionally, the mRNAs of Toll like receptors (TLR) and pro-inflammatory cytokines were evaluated by quantitative PCR to explore the immune responses induced by A. fumigatus. The results showed that overt depression, ruffled feathers, and dyspnea were observed in the infected chickens as early as 3 days post infection (dpi). Eleven out of 25 infected chickens died from 5 to 9 dpi, and A. fumigatus could also be reisolated from the infected lung. Histopathological examination revealed obvious airsacculitis and pneumonia, characterized by inflammatory cell infiltration (heterophils and macrophages), and granulomatous lesions in the lung. The mRNA expressions of TLR1 and TLR2 were upregulated in the lung and spleen, and most pro-inflammatory cytokines including IL-1β, Cxcl-8, TNF-α, IL-12, and IFN-γ were increased in both the lung and spleen during the tested period, suggesting that the innate immune responses were triggered by A. fumigatus infection, and these cytokines participated in the inflammatory responses against A. fumigatus. These results indicate that A. fumigatus infection by thoracic intra-air sacs inoculation can cause severe respiratory damage in chickens, activate TLR1 and TLR2 mediated immune responses, and elicit large expression of pro-inflammatory cytokines such as IL-1β, Cxcl-8, and IFN-γ. These data will help further understanding of the pathogenesis and immune responses of A. fumigatus infection in the chicken.

Keywords: Aspergillus fumigatus; TLR signaling; chicken; pathogenicity; pro-inflammatory cytokines.