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Tembusu virus (TMUV) is a significant pathogen that poses a considerable threat to the waterfowl farming industry in China and is classified into three distinct genetic clusters. In 2024, a suspected outbreak of TMUV infection was reported at a goose farm in Guangdong Province, China. A strain of TMUV, designated GDE19-2024, was successfully isolated using chicken embryos. Homology and genetic evolutionary analyses suggest that GDE19-2024 is categorized within cluster 3 of TMUV and exhibits a close genetic affiliation with other strains in this cluster. Nonetheless, GDE19-2024 has experienced two distinct mutations at the 149th and 157th amino acid positions of the E protein, setting it apart from other TMUV strains within cluster 3. The pathogenicity assay revealed that the GDE19-2024 strain possesses the ability to infect both geese and ducks, leading to viremia and effective viral replication in multiple organs. Notably, GDE19-2024 demonstrated considerable pathogenicity in goslings, resulting in a mortality rate of 62.5 % among 7-day-old goslings and causing hemorrhagic lesions in various organs of the infected geese. Conversely, GDE19-2024 exhibits relatively low pathogenicity in ducks, as evidenced by the manifestation of only mild and transient clinical symptoms in infected ducklings, without resulting in mortality. Furthermore, the extent of organ damage in ducks is less severe compared to that observed in infected goslings. This observation suggests that cluster 3 TMUV may be more adapted to geese, exhibiting increased pathogenicity in this species. Our findings provide a foundational basis for understanding the genetic evolution and pathogenicity of cluster 3 TMUV in China.

Abstract Background Porcine respiratory and reproductive syndrome virus (PRRSV) is one of the most economically significant pathogens in the Chinese swine industry. ORF5 and nsp2 are highly variable regions of the PRRSV genome. Therefore, nsp2 and GP5 are often selected for investigation of variations and phylogenetic analyses for their genetic diversities. Knowledge of the molecular evolution of PRRSV field strains may contribute to the control of PRRS in China. Results The results of multiple sequence alignments of GP5 showed that there is 84.5–100% aa identity among the 56 strains in this study. These strains shared 84.5–99.0% aa identity with the prototypical type 2 PRRSV VR-2332 and 56.6–59.2% with strain LV, prototypical type 1 PRRSV. Phylogenetic analysis showed there is considerable diversity among PRRSV ORF5 and the existence of two lineages (5 and 8). Most of the strains were classified into lineage 8 with multiple sub-lineages (3, 4 and 6). Moreover, PRRSV strains with 5 novel patterns of deletions or insertions in the nsp2 region were found. Conclusions Phylogenetic analysis based on ORF5 sequences indicated the diversity of PRRSV in southern parts of China and the strains with 30 aa deletion in nsp2 are dominant in the porcine population. Also, new PRRSV strains with different patterns of deletions or insertions in nsp2 are emerging. The data presented here constitute a useful basis for further epidemiological studies regarding the heterogeneity of PRRSV strains in China and provide a basis for the prevention of PRRS in southern parts of China.

Astroviruses are single-stranded, positive-sense RNA viruses capable of infecting humans as well as a wide range of mammalian and avian species, with a length of approximately 6.6–7.7 kb. In this study, 139 goat fecal samples collected from the Guangxi province were used for the RT-PCR detection, and two of these were positive for goat astrovirus, with a positivity rate of 1.44% (2/139). The complete genome sequence of an astrovirus strain and the partial genome sequence of a strain astrovirus, named GX WZ 2023 and GX HC 2023, were amplified and sequenced, and their sequence lengths were 6284 nt and 6213 nt, respectively. Among them, the capsid protein of goat astrovirus GX HC 2023 showed the highest amino acid identity of 95.9% with ovine astrovirus GX, which belonged to the MAstV-2 genotype. However, the closest relative of the GX WZ 2023 strain was found to be the caprine astrovirus Sichuan, with a nucleotide sequence identity of 76.8%. The ORF1ab nonstructural protein of this strain showed the highest amino acid identities of 89.2 and 95.8% with the ovine astrovirus S5.1 and caprine astrovirus G5.1 strains, respectively. However, its ORF2 capsid protein has 68.4% amino acid identity with the bovine astrovirus (BAstV) 16 2021 CHN strain and only 21.9–64% amino acid identity with all available strains of goat astrovirus. The GX WZ 2023 strain was recombined with the Chinese (BAstV 16 2021 CHN) and Japanese bovine strains (BAstV JPN 2015) in the ORF2 region. Therefore, the goat astrovirus GX WZ 2023 is proposed as a new member of the family goat astroviridae based on the species classification criteria of the International Committee on Taxonomy of Viruses. These findings enhance our understanding of the prevalence and genetic evolution of goat astrovirus and provide a scientific basis for future studies of these viruses in other animals. [ABSTRACT FROM AUTHOR]

Ammonia and microcystin-LR (MCLR) are commonly found pollutants in aquatic environments around the world. To explore the potential synergistic effects of ammonia and MCLR on the zebrafish intestine, adult female zebrafish were exposed to total ammonia nitrogen (30 mg⋅L-1),MCLR (10 µg⋅L-1) and a mixture of both (30 mg⋅L-1 + 10 µg⋅L-1) for a period of 30 d. Histopathological analysis showed that ammonia exposure led to a decrease in intestinal villis area, while MCLR exposure caused villus rupture and increased the ratio of vacuolization in intestines. The combination of ammonia and MCLR resulted in more serious damage in the intestine. Ammonia alone and in combination with MCLR significantly reduced the contents and related gene expression levels of intestinal lysozyme and β-defensin compared with the control group, indicating suppressed intestinal immunity in zebrafish. Moreover, the single and combined exposure to ammonia and MCLR increased the mRNA expression levels and contents of intestinal inflammatory factors IL-1β and TNF-α by activating NOD1/2 and TLR4a/4b signal pathways, leading to intestinal inflammation. Results of intestinal microbiota showed that both ammonia and MCLR caused changes in diversity. Ammonia nitrogen increased the richness of Firmicutes, while MCLR increased the richness of Actinobacteria and decreased the richness of Proteobacteria. The combined exposure to ammonia and MCLR significantly increased the abundance of Pseudomonas and Mycobacterium. Furthermore, their combined exposure reduced the number of OTUs of short-chain fatty acids producers and the contents of short-chain fatty acids in the intestine. In conclusion, the combination of ammonia and MCLR has a synergistic effect on the intestinal immunity and structure of intestinal flora in zebrafish, and their combined effects on the health of aquatic animals and the water ecosystem's integrity should not be underestimated. [ABSTRACT FROM AUTHOR]