Human babesiosis, an emerging zoonosis with ongoing geographic expansion, is primarily caused by Babesia microti, a tick-borne apicomplexan parasite that resides within host erythrocytes. While small mammals serve as its recognized reservoir hosts, the relative contribution of sympatric wild rodents and shrews in subtropical mountain endemic areas of Eastern China remains poorly characterized. In South-central Zhejiang, an endemic focus of human babesiosis, systematic data on local small-mammal hosts remain limited. In this study, 630 small mammals, comprising six rodent species and the shrew Suncus murinus, were captured across six counties in Zhejiang Province of China. Host identity was confirmed by morphological examination and mitochondrial cytochrome b (cytb) barcoding. Whole-blood DNA was screened for B. microti by TaqMan real-time quantitative PCR (qPCR); positive specimens were further analyzed by nested PCR (NPCR) targeting the 18S rRNA gene, followed by sequencing for genotype identification. The overall qPCR-positive rate was 3.0% (19/630). Geographically, B. microti infections were detected in four out of six surveyed counties, with Jinyun County showing the highest prevalence of 6.9%, followed by Qingyuan (4.0%), Wencheng (3.2%), and Qingtian (3.0%); no positive samples were identified in the Yunhe and Jingning counties. Among the sampled species, Niviventer lotipes showed the highest prevalence (11.7%, 12/103), followed by S. murinus (3.8%, 2/52), Alexandromys fortis (3.7%, 3/81), Apodemus agrarius (1.0%, 1/99), and Rattus norvegicus (0.5%, 1/222). No positive results were detected in R. tanezumi (n = 62) or Leopoldamys edwardsi (n = 11). Fifteen of the 19 samples yielded positive amplification by NPCR and were successfully sequenced. All 15 sequenced isolates were assigned to the Kobe genotype and exhibited close genetic relatedness to previously reported local human-derived and tick-derived strains. The dominance of a single haplotype (n = 14) across host species and counties indicates genetically homogeneous circulation of the Kobe genotype within local small-mammal communities, with host species rather than sampling county as the significant determinant of infection risk. These findings suggest that N. lotipes may be an important reservoir host in this region, and shrews may represent understudied secondary hosts, supporting the inclusion of both rodents and shrews in regional babesiosis surveillance.
African buffalo (Syncerus caffer) are the primary wildlife reservoir for bovine tuberculosis (BTB) in Africa. Infected buffalo populations spread BTB to numerous species in conservation areas as well as to cattle at park boundaries. Quarantine requirements for BTB complicate wild animal metapopulation management. Considerable interest has arisen in the vaccination of cattle and indigenous wildlife species against BTB as an additional control strategy. This pilot trial aimed to evaluate cell-mediated and humoral immune responses in African buffalo immunised against BTB. Twenty-one sub-adult African buffalo were divided into four treatment groups, and received either Bacillus Calmette-Gu & eacute;rin (BCG; 106 CFU) intra-muscularly, a heat-inactivated Mycobacterium bovis vaccine intra-muscularly (HIMB-IM; 107 CFUs; followed by a boost after 4 months) or orally (HIMB-O; 107-108 CFU), or 1 mL phosphate-buffered saline (PBS) intra-muscularly (control group). 7 months after immunisation, all animals were intratracheally challenged with M. bovis (2 & times; 105 CFU). Monthly Bovigam interferon-gamma (IFN gamma) assays and M. bovis-specific ELISAs were conducted and in addition, comparative intra-dermal tuberculin testings (CITTs) were performed at study start and termination 5 months after experimental infection. Over the study period, each treatment group showed distinct cell-mediated responses which differed in strength and temporal dynamics. In the post-immunisation stage, HIMB-IM animals produced a strong increase in bovine-avian purified protein derivative (PPD) IFN gamma release after booster immunisation while HIMB-O and BCG groups showed relatively fewer numbers of positive responses. The experimental infection triggered significant elevations in bovine-avian PPD IFN gamma release in all treatment groups. All animals were converted to bovine reactors. Both HIMB groups showed stronger IFN gamma responses compared to the BCG and control groups in the early post-infection period, suggesting superior immune priming. Antibody responses showed marked individual variation, episodic interference from non-tuberculous mycobacterial (NTM) species and low test sensitivity and specificity.
H9N2 avian influenza viruses (AIVs) continue to cause disease in poultry and pose a zoonotic risk. In South Korea, live bird markets (LBMs) serve as evolutionary epicenters for H9N2 AIVs, facilitating interspecies transmission and genetic reassortment. To improve surveillance efficiency, environmental sampling was conducted at two LBMs in Korea between November 2023 and May 2025. A total of 486 samples, comprising 190 poultry swab samples, 179 environmental samples, and 117 tissue samples, were collected. A sample was considered positive when virus isolation in embryonated eggs yielded hemagglutination‐positive allantoic fluid that was subsequently confirmed as AIV by matrix (M)‐gene real‐time reverse transcription PCR (rRT‐PCR). Drinking water showed the highest AIV isolation rate (15.7%). Whole‐genome sequencing of 45 isolates revealed that all viruses belonged to clade B4.6.1 of the B‐lineage (formerly Y280). Phylogenetic analysis suggested the presence of two distinct temporal clusters: the 2023 cluster, which was not detected after November 2023, and the 2024–2025 cluster, which appeared to continue circulating in Korean LBMs. A historical reassortment involving PB1 and PA segments from clade B4.7 H9N2 viruses was inferred to have occurred prior to the introduction of the B‐lineage into Korea. An isolate (N22‐97) exhibited evidence of reassortment between the temporal clusters within clade B4.6.1: its PA segment clustered with the 2024–2025 viruses, whereas the remaining segments clustered with the 2023 viruses. Multiple mammalian‐adaptive mutations (e.g., HA‐226L and PB2‐598I) were identified, with genetic variation observed in drinking water‐derived isolates. Single nucleotide variant (SNV) analysis revealed HA‐A190T/V and HA‐V318I variants, suggesting the presence of mixed viral populations within LBM environments. Sequence‐based antigenic mapping identified five putative antigenic clusters, with most isolates—including the current Korean B‐lineage vaccine strain—grouping within the dominant cluster. These findings highlight drinking water as a useful environmental matrix for AIV monitoring and underscore the value of environmental genomic surveillance for AIV detection in LBMs.
Novel duck orthoreovirus (NDRV) represents a major pathogen severely affecting the waterfowl farming industry in China, yet its evolutionary dynamics and reassortment patterns remain poorly defined. In this study, we sequenced the full genomes of 10 NDRV isolates obtained from Shandong and Jiangsu provinces (2018–2023) and analyzed their genetic features through sequence identity, phylogenetics, and reassortment detection. We also evaluated pathogenicity in 1‐day‐old ducklings for three representative isolates via intravenous injection. Our results show that nucleotide (nt) homologies across all gene segments ranged from 86.9% to 99.9%, and the L2, M1, S2, and S4 segments displayed greater sequence variability than the traditionally hypervariable S1 gene in our isolates. We identified recombination events in the M2 segment of strain XT18 (with SDYC and HN5d as parental strains) and the S4 segment of strain LY20 (with GX‐Y7 and SDYC as parents), which, to our knowledge, represent the first reports of recombination in the M2 and S4 segments of NDRV. In pathogenicity tests, strain SDYC induced the most severe splenic lesions and maintained the highest viral loads in vivo. Collectively, these findings clarify the molecular evolution and reassortment landscape of currently circulating NDRV strains and offer a scientific basis for selecting vaccine candidates and designing precision control strategies.
Brucella spp. are facultative intracellular bacteria that infect and induce brucellosis in a diverse range of mammalian hosts. Understanding the mechanisms underlying the intracellular survival of Brucella is of critical importance for the prevention and control of brucellosis. This study uncovers the mechanism by which Brucella abortus manipulates host lactate metabolism to facilitate its intracellular proliferation. Infection of macrophages by B. abortus enhanced L‐lactate production by the host macrophages, which in turn promoted bacterial proliferation. Proteomic and functional analyses identified the host glucose transporter protein Slc2a1 as a positive regulator of both B. abortus proliferation and host cellular lactylation. The B. abortus effector protein SepA upregulated Slc2a1 expression and host cellular lactylation. Lactylation of the transcription factor USF2 at lysine residues 255 and 275 suppressed production of the host lipid metabolism‐associated protein Fabp4, thereby enhancing bacterial survival. Moreover, Fabp4 inhibition attenuated B. abortus ‐induced M1 polarization and lipid metabolism in macrophages. These findings reveal a dual‐axis regulatory network through which B. abortus exploits host L‐lactate metabolic reprogramming via the SepA/Slc2a1 and L‐lactate‐USF2/Fabp4 axes to establish its intracellular niche, providing new insights into host– Brucella metabolic crosstalk.
