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Bovine mastitis, especially subclinical mastitis (SCM), is one of the most prevalent and economically costly diseases in the dairy industry worldwide. Understanding the prevalence and spatial distribution of bovine SCM and its associated risk factors will facilitate the prevention and control of the disease. We reviewed published studies pertaining to epidemiological surveys of SCM among dairy cows during the past decade (2012-2021) in China from inception to March 20, 2020, with PubMed, Clinical Trial, VIP, CNKI and databases being used to identify English and Chinese articles. Therefore, we retrieved 41 studies related to epidemiological surveys of SCM among dairy cows, using our eligibility criteria. We demonstrated that the prevalence of SCM in dairy cows was 37.7% during the selected periods, indicating a slight increase in the incidence of SCM in a comparison between 2012 and 2016 and 2017-2021. The estimated prevalence of SCM was 36.4%-50.2% in the seven regions, which was no statistically significant difference. The highest prevalence of SCM was 72% in Inner Mongolia Autonomous Region, and the lowest prevalence was 19% in Hubei Province. The variation in diagnostic methods was not significant in the studies. Dairy cows' parity was a risk factor associated with the prevalence rate of SCM. Cow's age might affect the prevalence of SCM during the selected periods. This study may facilitate the control with specific strategies to reduce costs and antibiotics overuse, enhance food safety and public health.

Although the immunogenicity of DNA vaccines is nonideal, they are still considered as potential alternative vaccine candidates to conventional vaccines. Various DNA delivery systems, including nanoparticles, have been extensively explored and validated to further enhance the immunogenicity of DNA vaccines. DNA vaccines are considered as alternative vaccine candidates. Various DNA delivery systems, including nanoparticles, have been extensively explored to enhance the immunogenicity of DNA vaccines. In this study, positively charged Poly (D, l-lactide-co-glycolic acid) (PLGA) nanoparticles were generated and characterized as a delivery system for O-serotype foot-and-mouth DNA vaccine. A recombinant plasmid encoding swine interleukin (IL)-18, IL-2, or granulocyte-macrophage colony-stimulating factor (GM-CSF) gene was introduced into the DNA vaccine to further improve its immunogenicity, which was evaluated in a guinea pig model. PLGA-pVAX-VP013/IL-18 elicited significantly (P = 0.0149) higher FMDV-specific antibody levels than naked DNA before the challenge. The level of neutralizing antibodies induced by PLGA-pVAX-VP013/IL-18, PLGA-pVAX-VP013/IL-2, and PLGA-pVAX-VP013/GM-CSF significantly increased compared with that induced by naked DNA (P 0.0001). The lymphocyte proliferation assay showed that cellular immunity induced by PLGA-pVAX-VP013/IL-18 and PLGA-pVAX-VP013/GM-CSF was dramatically enhanced compared with that induced by the inactivated vaccine. The protection by PLGA-pVAX-VP013/IL-18 was consistent with that by the inactivated vaccine post-challenge and was followed by PLGA-pVAX-VP013/GM-CSF. Therefore, cationic PLGA nanoparticles can deliver DNA vaccines and induce humoral and cellular immune responses. The co-administration of FMD DNA vaccine with IL-18 formulated with PLGA nanoparticles was the optimal strategy to improve the immunogenicity of FMD DNA vaccines.

Pullorum disease (PD), caused by the bacterium Salmonella pullorum, severely threatens the health of chickens worldwide, especially in China, and generating concerns for public health safety. Greater awareness of the seroprevalence may facilitate the prevention and control of this disease. We conducted systematic review and meta-analysis on the seroprevalence of PD in chicken flocks across mainland China. The results show that the overall pooled estimates of PD seroprevalence in chicken flocks was 18.2%. Furthermore, during 38-year period the seroprevalence of PD was markedly high in all seven regions, being at least 14.9% in central China. Our results suggest PD was highly prevalent in autumn, followed by winter. Chickens older than 120 days (22.6%, CI

Pasteurella multocida (PM) causes a varity of clinical manifestation in domestic animals, even acute death. Vaccination is among effective strategy to prevent and control PM-related diseases. Bacterial ghosts (BGs) are empty bacterial envelopes, which sustain subtle antigenic comformation in bacterial outer-membrane and exhibit higher efficacy compared to inactivated vaccines. Here, a BG vaccine generated from the porcine PM reference strain CVCC446 (serotype B:2) was prepared upon lysis by E protein of bacteriophage PhiX174, and the safety and immunogenicity were evaluated its in a mouse model. Lysis rate was in 99.99% and the BG vaccine was completely inactivated by addition of freeze-dry procedure. Mice were immunized subcutaneously twice in 2-week intervals with BGs, or BGs plus adjuvant, or formalin-inactivated PM or an adjuvant control. Mice inoculated twice with BGs vaccines generated higher titer of antibodies, interleukin 4 and gamma interferon than those in the inactivated vaccine group or adjuvant placebo group (P 0.05). CD4

Foot-and-mouth disease (FMD) is a highly contagious disease that affects all susceptible cloven-hoofed animals, resulting in considerable economic losses to animal industries worldwide. Numerous categories of enzyme-linked immunosorbent assays (ELISA) have been developed and widely used to evaluate herd immunity. Manufacturing inactivated FMD virus (FMDV) as a diagnostic antigen requires a facility with a high level of biosafety, but this requirement raises concern on viral leakage. In our previous study, bacterium-original FMD virus-like particles (VLPs) resemble the authentic FMDV and induce protective immunity against homologous viral challenges, thereby demonstrating that they are sufficiently safe without limitations on biosafety facilities and easily prepared. Herein, we developed a competitive ELISA (cELISA) based on FMDV-VLPs as a diagnostic antigen to evaluate herd immunity. The criterion of this cELISA was determined by detecting panels of positive sera with different antibody titers and negative sera. The working parameter of cELISA was optimized, and samples with a percentage inhibition of ≥ 50% were considered positive. The specificity of cELISA to test 277 serum samples with various antibody titers was 100%, and the sensitivity reached 96%. The coincidence rates of cELISA with a VDPro® FMDV and a PrioCHECK® FMDV type O antibody ELISA kit were 97.8% and 98.2%, respectively. Repeatability tests demonstrated that the coefficients of variation within and between runs were less than 7% and 14%, respectively. Our data demonstrated that cELISA based on bacterium-original VLPs had high specificity, sensitivity, and reproducibility. The cELISA could also be used for evaluating vaccination herd immunity effects, especially in developing countries.

Bovine viral diarrhea virus (BVDV) infection causes significantly economic losses to cattle industry worldwide, also including China. The epidemiological prevalence of infection associated with BVDV in dairy cattle has not been systematically assessed in China. Therefore, we undertook this study to evaluate prevalent of BVDV infection. We conducted a systematic review and meta-analysis of data from papers on the BVDV incidence and prevalence in dairy cattle in China by searching China Science and Technology Journal Database, China National Knowledge Infrastructure (CNKI), Wan Fang Database and PubMed for publication from March 2003 to March 2018. The 41 studies reporting the prevalence of BVDV in cattle in China were selected upon our inclusion criterion. The pooled BVDV prevalence in dairy cattle in China was estimated to 53.0% (95% CI 40.2–65.7) based on the data obtained from the 27,530 cows tested using serological or virological assay in the qualified papers published during the periods (χ² = 51,861.0, I2 = 99.9%). The highest BVDV positive rate in dairy flocks reached 90.0% in Fujian province of China, followed by Shaanxi (88.9%) and Shandong (83.3%). The prevalence in the six administrative districts of China was validated to be highly variable (25.7%–72.2%) and reached 72.2% in dairy cattle flocks of Northern China. Besides, the BVDV-RNA positive rate was estimated 27.1% (95% CI 17.3–37.0) based on 6 studies, comparatively, the pooled BVDV seroprevalence based on 35 studies was about 57.0% (95% CI 44.4–69.5) in China. This systematic review and meta-analysis firstly established an estimated prevalence of BVDV in dairy herds in China, indicating that the BVDV infection is escalating, though there is a bias in the number of studies between 2003–2009 and 2010–2018 timescales. This study may help understand the status of BVDV infection in dairy herds in China. Further extensive and comprehensive investigation is recommended, and effective intervention measures for preventing and controlling BVDV spread in dairy herds should be deployed, especially herds that have been exposed to BVDV.

Bovine herpesvirus type 1 (BoHV-1) causes considerable economic losses to the cow industry. Vaccination remains an effective strategy to control the diseases associated with BoHV-1. However, live vaccines present safety concerns, especially in pregnant cows; thus, nonreplicating vaccines have been developed to control the disease. The envelope glycoproteins of BoHV-1 induce a protective immune response. In this work, selected epitopes on glycoproteins gD, gC, and gB were constructed in triplicate with linker peptides. Vaccination of rabbits demonstrated that P2-gD/gC/gB with AAYAAY induced higher specific antibodies than that with GGGGS linker. P2-gD/gC/gB with AAYAAY linker was fused with bovine interleukin-6 (BoIL-6) or rabbit IL-6 (RaIL-6) and bacterially expressed. Rabbits were intramuscularly immunized with 100 μg of P2-gD/gC/gB-BoIL-6, P2-gD/gC/gB-RaIL-6, P2-gD/gC/gB, P2-gD/gC/gB plus BoIL-6, P2-(gD-a)3-BoIL-6, or P2-(gD-a)3 emulsified with ISA 206 adjuvant thrice at 3-week intervals. P2-gD/gC/gB-BoIL-6 generated a higher titer of BoHV-1-specific antibodies, neutralizing antibodies, interferon (IFN)-γ, and IL-4 compared with P2-gD/gC/gB plus BoIL-6, P2-gD/gC/gB-RaIL-6, or other formulation. P2-gD/gC/gB-BoIL-6 triggered similar levels of antibodies and significantly higher titer of IFN-γ and IL-4 compared with inactivated bovine viral diarrhea (BVD)-infectious bovine rhinotracheitis (IBR) vaccine. Rabbits vaccinated with P2-gD/gC/gB-BoIL-6 dramatically reduced viral shedding and tissue lesions in lungs and trachea after viral challenge and reactivation compared with those with P2-gD/gC/gB plus BoIL-6 or P2-gD/gC/gB-RaIL-6. P2-gD/gC/gB-BoIL-6 provided protective effects against viral shedding and tissue pathogenesis similar to those of the inactivated vaccine. The data confirmed the safety and immunogenicity of multiple-epitope recombinant protein and a potential vaccine candidate to control the disease, especially for pregnant cattle.

Bovine herpesvirus type 1 (BoHV-1), a member of the Alphaherpesvirinae subfamily, causes significant economic losses to the cattle industry worldwide. Envelope glycoprotein D (gD) of BoHV-1 plays an essential role in the viral entry into permissive cells and possibly cooperates with other envelope glycoproteins. The herpesvirus gD induces a protective immune response against diseases in cattle or animal models. Mapping epitopes on gD will facilitate the understanding of the BoHV-1 pathogenesis and development of alternative vaccines against various diseases associated with the virus. In this study, a monoclonal antibody (MAb), designated as 3C1, was generated using naive BoHV-1 in vaccination of mice, demonstrating that 3C1 was specific to gD and represents a neutralizing activity against BoHV-1 infection in Madin-Darby bovine kidney cells. Panels of overlapping gD recombinant proteins with glutathione S-transferase tag were prepared to define the epitope recognized by 3C1. The data demonstrated that the N-terminus of gD 23APRVTVYVD31 was recognized by 3C1. Furthermore, the 26VTVYVD31 motif was the minimal amino acid sequence for the recognition. The epitope identified in this study is highly conserved among the typical strains of BoHV-1 and BoHV-5, suggesting that this epitope may be useful in the diagnosis of diseases. In addition, the defined region on gD of BoHV-1 might be essential in viral entry upon comparison with the prototype virus in herpes simplex virus (Alphaherpesvirinae). The data will elucidate the roles of gD of BoHV-1 in viral entry and pathogenesis and its potential application for the development of vaccine candidates and diagnostic techniques based on the conserved epitopes on gD or in combination with those of other herpesvirus glycoproteins.

Mammalian orthoreoviruses (MRVs) have a wide range of geographic distribution and have been isolated from humans and various animals. This study describes the isolation, molecular characterization and analysis of pathogenicity of MRV variant B/03 from wild short-nosed fruit bats. Negative stain electron microscopy illustrated that the B/03 strain is a non-enveloped icosahedral virus with a diameter of 70 nm. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) migration patterns showed that the B/03 viral genome contains 10 segments in a 3:3:4 arrangement. The isolate belongs to MRV serotype 1 based on S1 gene nucleotide sequence data. BALB/c mice experimentally infected with B/03 virus by intranasal inoculation developed severe respiratory distress with tissue damage and inflammation. Lastly, B/03 virus has an increased transmission risk between bats and humans or animals., Highlights • A novel MRV strain was isolated from wild short-nosed fruit bats in China. • Phylogenetic analyses suggested B/03 is a serotype 1 MRV of reassortment strain. • Pathogenesis of B/03 strain was tested in BALB/c mice.

Background Brucellosis remains one of the most common zoonotic diseases globally, with more than half million human cases reported annually. Brucellosis is an emerging and re-emerging disease in China since the 1990s. An infectious reservoir constituted by domestic animals with brucellosis, especially ovine and caprine herds, poses a significant threat to public health. The seroprevalence of brucellosis in sheep and goat flocks in a national context is unavailable so far. Therefore, we conducted this systematic review and meta-analysis to assess the overall status of brucellosis in sheep and goats in China in almost two decades. Results The pooled prevalence of brucellosis in ovine and caprine flocks in China increased in 2000–2009 (1.00%; 95% CI, 0.70–1.30) to 2010–2018 (3.20%; 95% CI, 2.70–3.60). The seroprevalence of brucellosis in sheep and goat flocks was higher in Eastern China, with 7.00% of positive rate, than that in any other region, especially Shandong province (18.70%). Brucellosis is highly endemic in some local regions. The high prevalence of brucellosis in agricultural regions is suggestive of a shift of geographic distribution. The pooled prevalence of brucellosis is higher in goat flocks than in sheep flocks in China. Conclusions The overall data in this meta-analysis demands comprehensive intervention measures and further surveillance to facilitate the control of brucellosis in livestock. Further studies aimed at evaluating the risk factors associated with spreads of brucellosis in domestic animals unaddressed so far, and sufficient epidemiological data is important to the exploration and understanding of the prevalent status of brucellosis throughout the country and to disease control. Electronic supplementary material The online version of this article (10.1186/s12917-018-1715-6) contains supplementary material, which is available to authorized users.

Brucellosis remains one of the most common zoonotic diseases globally with more than a half million human cases reported annually. The Brucella reservoir associated with livestock brucellosis poses a significant threat to public health, and awareness of the seroprevalence and spatial distribution of livestock brucellosis is valuable for the prevention and control of diseases caused by Brucella, especially human brucellosis. Therefore, we conducted a systematic review and meta-analysis to evaluate the seroprevalence of brucellosis in dairy cattle in China. We retrieved 88 studies related to the seroprevalence of brucellosis in dairy cattle in China in which samples were harvested between 2008 and 2018. The results of our systematic review and meta-analysis reveal that the overall seroprevalence of brucellosis in dairy cattle herds in China was 1.9% during the selected period, rising from 1.6% in 2008-2012 to 2.6% in 2013-2018. In Northern China, where the traditional agropastoral areas with more developed animal breeding industry are located, the brucellosis seroprevalence was >10%. In contrast, the seroprevalence of brucellosis in Southern China reached only 5.5%. At the provincial level, the highest brucellosis seroprevalence in dairy cattle was estimated at >30% in Jilin province, followed by Shanxi, Ningxia, Inner Mongolia, and Guizhou, each with a prevalence of 10-20%. Additionally, the seroprevalence of brucellosis in some local areas was >30% or even >50%, indicating that Brucella infection was highly endemic in dairy herds in China. Our data may facilitate the prevention and control of brucellosis in domestic animals in China. Further epidemiological surveillance and the administration of a comprehensive monitoring program to determine the risk factors associated with brucellosis incidence in humans and domestic animals are recommended to refine brucellosis control strategies.

Enterotoxignenic Escherichia coli (ETEC)-associated colibacillosis causes high levels of morbidity and mortality in neonatal piglets. Vaccination is among effective strategy to fight against ETEC-related diseases. Bacterial ghosts (BGs) are empty bacterial envelopes, which substain subtle antigenic comformation in bacterial outer membrane. In this study, a BG vaccine was generated using porcine ETEC isolated strain DQ061 and evaluated its safety and immunogenicity in a mouse model. The recombinant bacteria were constructed by transformation of lysis plasmid pHH43 and generation of BGs was conducted in a lysis rate of 99.93% by incubation of the recombinant bacteria at 42 °C for 2 h. Mice were immunized subcutaneously twice in 2-week intervals with BGs, BGs emulsified with ISA 206 adjuvant, or formalin-inactivated ETEC vaccine after safety test. Mice with either of two BG vaccines developed higher titer of antibodies, secreted higher titer of interleukin 4, gamma interferon and alpha tumor necrosis factor after 2 doses than those with formalin-inactivated ETEC vaccine or those with adjuvant placebo (P 0.01). The quantity of CD4

The two DNA fragments encoding predicted main antigenic regions, aa 20–160 and aa 257–344 on gD protein of bovine herpesvirus-1 (BoHV-1) were tandem-cloned into the vector pET28a. The recombinant His-tagged Δ gD1-Δ gD2 was expressed in Escherichia coli BL21(DE3)pLysS by induction with 0.5 mM isopropyl-1-thio-β-D-galactoside (IPTG) and Western blot analysis demonstrated that the recombinant His-tagged Δ gD1-Δ gD2 reacted with the positive serum against BoHV-1. A monoclonal antibody (MAb), designated as 2B6, was prepared by fusion of SP2/0 myeloma cells with splenocytes from a female 8-week-old BALB/c mouse immunized with purified His-tagged Δ gD1-Δ gD2 protein with the addition of Freund's adjuvant. The titer of the ascitic fluid triggered by hybridoma cells secreting MAb 2B6 was 1:2.5 × 108 and the subtype of MAb 2B6 was IgG 2a/κ. MAb 2B6 positively recognized with BoHV-1 infected Madin-Darby bovine kidney cells by an indirect fluorescent antibody assay. Moreover, MAb 2B6 showed 1:160 viral neutralizing a...