Comparison of immunohistochemistry and Ziehl-Neelsen staining for detecting the distribution of Mycobacterium avium subsp avium in naturally infected domestic Pekin ducks (Anas platyrhynchos domestica)

Pasteurella multocida causes liver injury in ducks by mediating inflammatory, apoptotic and autophagic pathways

Pasteurella multocida.(PM) infection is a major cause of avian cholera, but the pathogenesis of the disease is unknown. The purpose of this study was to further understand the host response to infection by using a duck model of PM, 20 female ducks were divided into two groups (n = 10). One group was infected with PM, while the other served as an uninfected control group. The ducks were observed after infection and samples were collected for testing. In this study, we report the mechanism of PM-induced inflammation to further mediate apoptosis and autophagic signaling pathways in liver cells. Our results demonstrated that PM infection initially induces hemorrhagic and necrotic lesions in the liver tissue of duck, promoting inflammasome assembly and release, triggering inflammation. The TLR4/NF-κB axis activated and interacted with multiple inflammation-related proteins, including TNF-α and IL-1β, which affected apoptosis and autophagy. Tumor necrosis factor induced hepatocyte apoptosis was implicated in a wide range of liver diseases; the release of TNF-α and activation with NF-κB further incite apoptotic pathways,such as Bax/BCL2/caspase to promote apoptotic genes APAF1, Bax, Caspase3, BCL-2, p53, and Cytc expression. Finally, PM-induced autophagy suppressed liver injury by promoting the Beclin-1, LC3B, p62, and mTOR. Thus, liver injury caused by PM via promoting autophagy was induced. In conclusion, we analyzed the liver injury of ducks infected with PM, and confirmed that inflammation appeared in the liver; this was followed by the intricate interplay between inflammation, apoptosis, and autophagy signaling pathways. The observed results provided a reference basis for studying pathogenic mechanisms of PM-host interactions.

Identification and Phylogenetic Analysis of Mycobacterium avium subsp. avium Strain Isolated from Cow

Mycobacterium avium subsp. avium (MAA) is the main tuberculosis pathogen of poultry and wild birds. MAA can also infect mammals such as pigs, cattle, and horses and can pose a threat to people with low immunity. Here, we describe the first identification of MAA strain HJW isolated from a cow in Jilin Province, China. The isolate was completely sequenced and a phylogenetic analysis of its relationship to members of the Mycobacterium avium complex (MAC) was performed. The results revealed that strain HJW was type MAA based on the analysis of insertion sequence amplification and whole genome sequencing. The HJW genome size was 4,961,843 bp with a GC content of 69.28%. The strain was genetically most closely related to the Mycobacterium avium subsp. avium strain DSM 44156. This study suggests that MAA may pose an infection risk to cattle and provides data support for the phylogeny of Mycobacterium avium.

Comparison of immunohistochemistry and Ziehl-Neelsen staining for detecting the distribution of Mycobacterium avium subsp avium in naturally infected domestic Pekin ducks (Anas platyrhynchos domestica)

In order to detect the distribution of Mycobacterium avium subsp avium (MAA) in naturally infected domestic Pekin ducks, immunohistochemistry (IHC) and Ziehl-Neelsen (ZN) staining were used and compared. Six organs, the liver, spleen, lung, kidney, duodenum and pectoralis muscle, were collected from naturally infected Pekin ducks. Paraffin embedded tissues were examined, and the results were compared. Statistical analysis was performed using Chi-Square test. The results showed that the detection rates by IHC were similar with ZN staining in liver, lung, spleen and pectoralis muscle, but the detection rates by IHC were much higher than ZN staining in kidney and duodenum (p = .013, p = .0044). The liver (87.5%) and lung (81.3%) had the highest detection rates. Acid-fast bacilli (AFB) were primarily found intracellularly in six organs using ZN staining. Similarly, the MAA antigens in those selected organs were also detected in the cytoplasm with different cell types. Specifically, MAA antigen was distributed in epithelioid macrophages and necrotic centres within the liver, lung, spleen and kidney, while they were observed in macrophages of the lamina propria and duodenal glands and degenerative myocytes in the pectoralis muscle. This comparative study provides an important insight into the distribution of MAA in infected domestic ducks and indicates that the detection rate by IHC was higher than that of ZN staining.