Enterocytozoon bieneusi is a common species of microsporidia that not only influences human health but also threatens animal productive performance and value. However, there have been no systematic studies of the prevalence of E. bieneusi in sheep in China. A total of 953 fecal specimens were collected from sheep from 11 provinces across five regions of China and analyzed for E. bieneusi by nested PCR targeting the ribosomal internal transcribed spacer (ITS). Enterocytozoon bieneusi infections were detected in four regions, with an overall infection rate of 20.4% (194/953). The highest infection rate was detected in pre-weaned lambs (25.0%), followed by post-weaned lambs (22.2%) and adult sheep (14.6%). Enterocytozoon bieneusi was found in nine of the 11 tested provinces, with infection rates between 2.9–51.7%. Eleven genotypes were identified based on ITS analysis, including seven known genotypes (BEB6, CHG1, CHG3, CHS7, CHS8, COS-I and NESH5) and four novel genotypes (CHHLJS1, CHHLJS2, CHNXS1 and CHXJS1). All 11 genotypes were clustered into group 2, and the zoonotic genotype BEB6 was the dominant genotype (n = 129, 66.5%) in sheep. The prevalence of E. bieneusi was studied in five regions representing most areas where sheep are bred in China. This is the first report of E. bieneusi infection in sheep for seven Chinese provinces. Geographical differences were detected in the distribution of E. bieneusi genotypes, but no differences were found among sheep in different age groups. The zoonotic genotype BEB6 was the dominant genotype, indicating that sheep are a potential source of zoonotic microsporidiosis in China. These results improve our knowledge of the epidemiology of E. bieneusi in sheep in China.

Background/Objectives: Porcine circovirus type 2 (PCV2) infection causes porcine circovirus disease (PCVD), a global immunosuppressive disease in pigs. Its clinical manifestations include post-weaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS), which cause significant economic losses to the swine industry. The Cap protein, which is the major protective antigen of PCV2, can self-assemble to form virus-like particles (VLPs) in the insect baculovirus expression system. Few studies have compared the expression of Cap proteins in different baculovirus expression systems. Methods: In this study, we compared two commonly commercialized baculovirus construction systems with the Cap protein expression in various insect cells. Results: The results demonstrate that the flashBAC system expressed the Cap protein at higher levels than the Bac-to-Bac system. Notably, when expressing four copies of the Cap protein, the flashBAC system achieved the highest protein yield in High Five cells, where it reached 432 μg/mL at 5 days post-infection (dpi) with 27 °C cultivation. Animal experiments confirmed that the purified Cap protein effectively induced specific antibody production in mice and swine. Conclusions: This study provides critical data for optimizing the production of the PCV2 Cap protein, which is of great significance for reducing the production cost of PCV2 vaccines and improving the industrial production efficiency.

Echinococcus multilocularis is a parasitic tapeworm responsible for alveolar echinococcosis (AE), a life-threatening zoonotic disease. Understanding its genetic diversity and historical spread is critical for developing effective control measures. Previous studies have suggested Central Asia as a potential origin of the parasite, but comprehensive global analyses encompassing multiple regions and time periods have been limited. This study aimed to analyze the genetic diversity, population structure, and phylogeography of E. multilocularis by sequencing the complete mitogenome from 384 isolates from major endemic regions across the Northern Hemisphere. We sequenced 201 new E. multilocularis mitogenomes and combined these with 183 previously published sequences. Phylogenetic, haplotype network, pairwise fixation index (Fst), and principal-component analysis (PCA) analyses were performed to explore genetic diversity, population structure, and the historical spread of the parasite. Bayesian phylogeographic reconstruction was used to infer diffusion routes across the Northern Hemisphere. Our analysis identified five major clades, with high genetic diversity observed in samples from China-Xinjiang and China-Midwest. The parasite exhibited significant genetic differentiation between continents, with most clades tracing their origins to Central Asia. Phylogeographic analysis suggested that E. multilocularis spread from Central Asia to Europe, Japan, and North America, primarily through wildlife migration and human activities. This study supports the hypothesis that Central Asia is the evolutionary origin of E. multilocularis and provides insights into its historical and contemporary dispersal patterns. The findings highlight the importance of monitoring and controlling the spread of human AE, particularly in regions, with high genetic diversity, to prevent further spread.

Porcine circovirus type 2 (PCV2) infection causes porcine circovirus disease (PCVD), a global immunosuppressive disease in pigs. Its clinical manifestations include post-weaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS), which cause significant economic losses to the swine industry. The Cap protein, which is the major protective antigen of PCV2, can self-assemble to form virus-like particles (VLPs) when expression in the insect baculovirus expression system. Few studies have compared the expression of Cap proteins in different baculovirus expression systems. In this study, we compared two commonly commercialized baculovirus construction systems to expressing the Cap protein in various insect cells. The results demonstrated that the flashBAC system expressing Cap protein at higher levels than the Bac-to-Bac system. Notably, when expressing four copies of the Cap protein, the flashBAC system achieved the highest protein yield in High Five cells, reaching 432 μg/mL at 5 days post-infection (dpi) at 27°C cultivation. Animal experiments confirmed that the purified Cap protein effectively induced specific antibody production in mice and swine. This study provides critical data for optimizing the production of PCV2 Cap protein, which is of great significance for reducing the production cost of PCV2 vaccines and improving industrial production efficiency.