Enterocytozoon bieneusi is a common opportunistic pathogen that is widely detected in humans, domestic animals and wildlife, and poses a challenge to public health. The present study was performed to evaluate the prevalence, genotypic diversity and zoonotic potential of E. bieneusi among wildlife at Chengdu and Bifengxia zoological gardens in Sichuan Province, China. Of the 272 fresh fecal samples harvested from 70 captive wildlife species at Chengdu Zoo (n = 198) and Bifengxia Zoo (n = 74), 21 (10.6 %) and 22 (29.7 %) tested positive for E. bieneusi by internal transcribed spacer (ITS) sequencing analysis, respectively. Specifically, genotypes D, Peru 6, CHB1, BEB6, CHS9, SC02 and SC03, and genotypes D, CHB1, SC01 and SC02 were detected in the Chengdu and Bifengxia Zoo samples, respectively. Five known genotypes (D, Peru 6, BEB6, CHS9 and CHB1) and three novel genotypes (SC01, SC02 and SC03) were clustered into the zoonotic group (group 1) and host-adapted group (group 2). Multilocus sequence typing (MLST) analysis targeting three microsatellites (MS1, MS3 and MS7) and one minisatellite (MS4) were successfully sequenced for 37, 33, 35 and 37 specimens, generating 8, 3, 11 and 15 distinct locus types, respectively. Altogether, we identified 27 multilocus genotypes (MLGs) among the E. bieneusi isolates by MLST. These data highlight the high genetic diversity of E. bieneusi among zoo wildlife. To our knowledge, this is the first report on the prevalence and genotypic diversity of E. bieneusi infections among captive wildlife in zoos in southwest China. Notably, we identified three novel E. bieneusi genotypes, as well as six new mammalian hosts (Asian golden cats, Tibetian blue bears, blackbucks, hog deer, Malayan sun bears and brown bears) for this organism. Moreover, the occurrence of zoonotic genotypes suggests that wildlife may act as reservoirs of E. bieneusi that can serve as a source of human microsporidiosis. The findings presented here should contribute to the control of zoonotic disease in China.

Enterocytozoon bieneusi is one of the most prevalent causative species of diarrhea and enteric diseases in various hosts. E. bieneusi has been identified in humans, mammals, birds, rodents and reptiles in China, but few studies have reported E. bieneusi in horses. Therefore, the present study was conducted to assess the prevalence, molecular characteristics and zoonotic potential of E. bieneusi among horses in southwestern China. Three hundred and thirty-three fecal specimens were collected from horses on five farms in the Sichuan and Yunnan provinces of southwestern China. The prevalence of E. bieneusi was 22.5 % (75/333), as determined by nested polymerase chain reaction and sequencing analysis of the internal transcribed spacer region of the ribosomal RNA gene of E. bieneusi. Altogether, 10 genotypes were identified among the 75 E. bieneusi-positive samples: four of these genotypes were known (horse1, horse2, SC02 and D) and six were novel (SCH1-4 and YNH1-2). Multilocus sequence typing using three microsatellites (MS1, MS3 and MS7) and one minisatellite (MS4) revealed three, two, three and three genotypes at these four loci, respectively. In phylogenetic analysis, all the genotypes of E. bieneusi obtained in this study were clustered into three distinct groups: D, SC02 and SCH1-3 were clustered into group 1 (zoonotic potential); SCH4 was clustered into group 2 (cattle-hosted); whereas horse2, YNH1 and YNH2 were clustered into group 6 (unclear zoonotic potential). This is the first report of E. bieneusi among horses in southwestern China. This is also the first multilocus genotyping analysis using microsatellite and minisatellite markers of E. bieneusi in horses. The presence of genotype D, which was previously identified in humans, and genotypes SC02 and SCH1-3, which belong to potential zoonotic group 1, these results indicate that horses are a potential source of human E. bieneusi infections in China.

Porcine bocavirus (PBoV), classified within the genus Bocaparvovirus, has been reported worldwide. PBoV has been divided into group 1, group 2, and group 3. PBoV group 3 (G3) viruses are the most prevalent in China. Currently, effective serological methods for the detection of antibodies against PBoV G3 are limited. In this study, we developed an indirect ELISA using a synthetic VP1 peptide designed on the basis of the conserved region of the PBoV VP1 protein as a coating antigen. Through matrix titration, the optimal coating concentration of the VP1 peptide (0.5 μg/mL), serum dilution (1:200), and working concentration of the secondary antibody (1:50,000) were determined. The cutoff value of this developed ELISA was set as 0.4239. Further investigations revealed that this developed ELISA had no cross-reactivity with positive serum antibodies against FMDV-O, FMDV-A, PRV, ASFV, SF, PCV2, PEDV, and TGEV. The detection limit of the method was a 1:1600 dilution of standard positive serum against PBoV G3. The coefficients of variation for both the intra- and interassay data were lower than 10%. A total of 1373 serum samples collected from 12 provinces in China between 2022 and 2023 were subjected to indirect ELISA. The results showed that 47.56% of the samples were PBoV G3 positive. These results reveal that peptide-based ELISA is a reliable and cost-effective method for detecting PBoV G3 antibodies. It also facilitates the investigation of the prevalence and distribution of PBoV G3.

Nontoxigenic Bacteroides fragilis (NTBF) is defined by the absence of the bft gene and corresponding B. fragilis toxin production; however, nontoxigenic status alone does not establish uniform safety or probiotic function. This review critically evaluates strain-level biological characteristics, safety, mechanisms, metabolites, and disease-model evidence. Selected strains and defined strain-derived preparations, including ZY-312, HCK-B3, NCTC 9343-derived polysaccharide A, and ZY-312-derived zwitterionic capsular polysaccharide preparation TP2, have shown immunomodulatory, barrier-associated, and microbial-community-modulating activities, predominantly in vitro and in animal models. Direct causal evidence is limited to specific strain–preparation–host–model combinations, whereas many changes in cytokines, tight-junction-associated proteins, microbial composition, and organic-acid profiles remain functional or associative. Protective effects have been reported in preclinical models of inflammatory bowel disease, necrotizing enterocolitis, antibiotic-associated diarrhea, Clostridioides difficile infection, and enterotoxigenic B. fragilis (ETBF)-associated tumorigenesis. However, findings are highly dependent on the strain, preparation, dose, administration timing, host, and model. Safety remains incompletely resolved because the absence of B. fragilis toxin (BFT) does not exclude opportunistic or systemic infection, antimicrobial-resistance mobility, bacterial translocation, permeability changes, or adverse effects during long-term administration. Metabolic effects may also be beneficial or adverse depending on the strain, host dietary and genetic background, and experimental context. Human evidence is primarily observational, and robust intervention trials are lacking. Accordingly, NTBF should be regarded as a heterogeneous group of strain-specific live-biotherapeutic candidates requiring rigorous strain-specific manufacturing, potency, dose, antimicrobial-susceptibility, and safety evaluation.

Bovine coronavirus (BCoV) is a key pathogen causing calf diarrhea and bovine respiratory diseases, bringing sustained economic losses to the cattle industry. As an RNA virus, BCoV possesses high mutation and recombination capacities, leading to prominent genomic genetic diversity. The genome contains hypervariable and conserved regions, with the S (especially S1), HE and Open Reading Frame (ORF4) genes serving as major variation hotspots linked to viral antigenicity, tissue tropism shift and immune evasion. Host immune pressure drives strong positive selection on S protein antigenic variation. This review discusses existing research limitations and proposes future directions including genomic surveillance, reverse genetics verification and broad-spectrum vaccine development to support BCoV prevention and control.