Infection and innate immune mechanism of goose astrovirus

Molecular detection and identification of goose astrovirus in GuangDong Province, China

In recent years, Goose Astrovirus (GAstV) has become a major pathogen in China, afflicting geese with significant clinical manifestations like gout and urate deposits in organs. Notably, similar symptoms have emerged in ducks. From 2023 to 2024, 126 liver samples were collected from ducks in Guangdong Province, where farms reported emaciation, paralysis, and deaths. Metagenomic analysis pinpointed GAstV as the primary pathogen, with a 43.65 % confirmed positive rate via qPCR. A new strain, GD2406, was identified, showing 97.5 %-98.8 % similarity to 30 GAstV-2 strains in GenBank. GD2406 displayed 98.3 % and 97.7 % identity with the duck strains HNNY0620 and SDTA, and 98.3 % and 98.4 % identity with highly virulent GAstV strains HNKF-1 and HNSQ-6. Phylogenetic analysis indicated a genetic closeness between GD2406 and the goose strain HB01. There were 13 amino acid mutations, mainly within ORF2, and a single mutation differing from HNKF-1 and HNSQ-6, hinting at significant pathogenic potential for both ducks and geese. This study is the first to report GAstV causing severe symptoms and mortality in Muscovy ducks in Guangdong Province, suggesting ducks could be key hosts and underscoring the risk of cross-species transmission.

Microwaves Activate Immune Response and Promote Lymphocytes Proliferation of Wistar Rats

The potential effects of microwave radiation have gained increasing attention due to its widespread application in daily life. This study aimed to investigate its effects on rat immune function. Male Wistar rats were subjected to 2.856 GHz microwave radiation for 20 min. Cytokine levels in serum were measured by ELISA at 0 and 7 days' post-exposure. HE staining was used to observe the structure of the spleen. Morphology and proliferation of spleen mixed lymphocytes were detected after 24 h of culture, and proliferation was evaluated by the CCK-8 assay. Expression of HSP70 and calreticulin (CRT) was assessed by WB. Rats showed an increased secretion of inflammatory factors in serum. Spleen tissue revealed no significant damage. Compared to the control group, irradiated groups (R-0d and R-7d) showed a significant increase and thickening of the white pulp. The boundary between the red and white medulla in the R-7d group appeared blurred. CCK-8 assay showed that splenic mixed lymphocytes in the irradiated group showed a significant proliferation. There was no significant difference in HSP70 and CRT expression between the exposed and control groups. Microwave exposure might activate the immune system of rats, potentially triggering a T cell-mediated inflammatory response.

Effects and potential pathways of goose astrovirus infection on gosling hepatic lipid metabolism

Introduction

The adverse effects of goose astrovirus (GoAstV) on avian growth and health have been widely reported previously, while the stress reactions and corresponding mechanism of gosling liver responding to GoAstV infection remain not entirely clear.

Methods

One-day-old goslings inoculated subcutaneously with 2 × 10-6 TCID50 of GoAstV were employed as an experimental model, and the potential effects and pathways of GoAstV infection on gosling liver functions were investigated by combining the morphological, biochemical and RNA sequencing (RNA-seq) techniques.

Results

Structural and functional impairments were found in gosling livers post the virus infection, as characterized by the histological alterations in liver index and morphology of hepatic cord and sinuses, as well as the abnormal expression patterns of the cellular antioxidant, inflammation and apoptosis-related genes. RNA sequencing analysis were performed to investigate the underlying mechanism. Results showed that the analysis of screened 1949 differentially expressed genes (DEGs) were mainly enriched in GO terms related to organic immune defense and substance metabolism, and their corresponding KEGG pathways represented by PPAR signaling pathway, intestinal immune network for IgA production, and fatty acid metabolism and degradation, suggesting that the functions of avian immunity and lipid metabolism were greatly changed after the GoAstV infection. Finally, the lipid deposition in gosling hepatocytes were further demonstrated by the subsequent Oil red O staining, biochemical detection of serum TG and HDL-C, and the gene expression analysis including PPARα, PPARγ, ACSBG2, ACSL5, CPT1A and PCK1.

Discussion

Though limitations exist, the findings of this study are helpful to expand our understanding about the negative effects of GoAstV on goslings, and provide us with new clues for the salvaging of GoAstV-induced liver dysfunctions in poultry industry.

Genetic and structural factors contributing to the dominance and persistence of goose astrovirus type 2

RESEARCH HIGHLIGHTS

Goose astrovirus type 2 (GoAstV-2) became the dominant strain in China post-2017.GoAstV-2 exhibits weaker codon usage bias, enhancing adaptability across hosts.The stability of GoAstV-2 spike protein reduces mutation needs and selective pressure.GoAstV-2 low spike protein variability supports long-term persistence in host populations.

Current Situation of Goose Astrovirus in China: A Review

Gosling gout disease is an infectious disease caused by goose astrovirus (GAstV), which can result in urate deposition in the internal organs and joints of goslings. Since 2015, outbreaks of gosling gout disease have occurred in several goose-producing areas in China. Subsequently, the disease spread to the vast majority of eastern China, becoming a major threat to goose farms and causing huge economic losses to the goose industry. Meanwhile, GAstV can infect species of birds other than geese. It is worth noting that, as an emerging virus, the research on GAstV is still in the early stages. Therefore, the investigation of GAstV has become an urgent issue, which can improve understanding of GAstV and develop effective measures to control its threat to poultry. The purpose of this review is to summarize the latest research progress on GAstV in recent years, mainly focusing on the genetic evolution, pathogenesis, diagnostic detection, and control strategies of GAstV, aiming to provide a reference for scientific prevention and control of GAstV infection.

Molecular epidemiology and virulence of goose astroviruses genotype-2 with different internal gene sequences

Goose astrovirus (GAstV) is a small, non-enveloped, single-stranded, positive-sense RNA virus. GAstV has rapidly spread across various regions in China since 2016. In Sichuan, out of 113 samples were collected from goose diseases between 2019 and 2022, 97 were positive for GAstV through PCR testing. Remarkably, over the past three years, GAstV outbreak in Sichuan has accounted for an astonishing 85.8% of all goose-origin viruses. Among these cases, 63.9% had single GAstV infections, 29.9% had dual infections, and 6.2% had quadruple infections. To comprehend the variations in virulence among distinct strains of GAstV. 12 representative strains of single GAstV infections were isolated. These strains exhibited distinct characteristics, such as prominent white urate depositions in organs and joints, as well as extensive tissues phagocytosis in major target organs' tissues. The conserved ORF1b genes and the variable ORF2 genes of these representative GAstV strains were sequenced, enabling the establishment of phylogenetic trees for GAstV. All GAstV strains were identified as belonging to genotype-2 with varying internal gene sequences. Experiments were conducted on GAstV genotype-2, both in vivo and in vitro, revealed significant variations in pathogenicity and virulence across susceptible cells, embryos, and goslings. This comprehensive study enhances researchers' understanding of the transmission characteristics and virulence of GAstV genotype-2, aiding in a better comprehension of their molecular epidemiology and pathogenic mechanism.