Prevalence, geographic distribution and risk factors of Eimeria species on commercial broiler farms in Guangdong, China.

BACKGROUND: Coccidiosis is one of the most frequently reported diseases in chickens, causing a significant economic impact on the poultry industry. However, there have been no previous studies evaluating the prevalence of this disease in broiler farms in Guangdong province. Therefore, this study aims to conduct an epidemiological investigation into the occurrence of Eimeria species and associated risk factors in intensive management conditions across four regions in Guangdong province, China. A total of 394 fecal samples were collected from 89 broiler farms in Guangdong province. The prevalence of Eimeria species infection was determined using PCR, and the occurrence of Clostridium perfringens type A was assessed using quantitative real-time PCR. RESULTS: The results showed an overall prevalence of 98.88% (88/89) at the farm level and 87.06% (343/394) at the flock level. All seven Eimeria species were identified, with E. acervulina (72.53%; 64/89), E. tenella (68.54%; 61/89), and E. mitis (66.29%; 59/89) at the farm level, and E. acervulina (36.55%; 144/394), E. mitis (35.28%; 139/394), and E. tenella (34.01%; 134/394) at the flock level. The predominant species combination observed was a co-infection of all seven Eimeria species (6.74%; 6/89), followed by a combination of E. acervulina, E. tenella, E. mitis, E. necatrix, E. brunetti, and E. maxima (5.62%, 5/89). A combination of E. acervulina, E. tenella, E. mitis, E. necatrix, E. brunetti, and E. praecox (4.49%; 4/89) was also observed at the farm level. Furthermore, the study identified several potential risk factors associated with the prevalence of Eimeria species, including farm location, chicken age, drinking water source, control strategy, and the presence of C. perfringens type A were identified as potential risk factors associated with prevalence of Eimeria species. Univariate and multivariate analyses revealed a significant association between E. necatrix infection and both grower chickens (OR = 10.86; 95% CI: 1.92-61.36; p < 0.05) and adult chickens (OR = 24.97; 95% CI: 4.29-145.15; p < 0.001) compared to starter chickens at the farm level. Additionally, farms that used groundwater (OR = 0.27; 95% CI: 0.08-0.94; p < 0.05) were less likely to have E. maxima compared to those that used running water. At the flock level, the prevalence of E. tenella was significantly higher in the Pearl River Delta (OR = 2.48; 95% CI: 1.0-6.15; p = 0.05) compared to eastern Guangdong. Interestingly, flocks with indigenous birds were less likely to have E. brunetti (OR = 0.48; 95% CI: 0.26-0.89; p < 0.05) compared to flocks with indigenous crossbred birds. Furthermore, flocks that used anticoccidial drugs (OR = 0.09; 95% CI: 0.03-0.31; p < 0.001) or a combination of vaccines and anticoccidial drugs (OR = 0.06; 95% CI: 0.01-0.25; p < 0.001) were less likely to be positive for E. tenella compared to flocks that only used vaccines. Finally, flocks with C. perfringens type A infection were significantly more likely to have E. necatrix (OR = 3.26; 95% CI: 1.96-5.43; p < 0.001), E. tenella (OR = 2.14; 95% CI: 1.36-3.36; p < 0.001), E. brunetti (OR = 2.48; 95% CI: 1.45-4.23; p < 0.001), and E. acervulina (OR = 2.62; 95% CI: 1.69-4.06; p < 0.001) compared to flocks without C. perfringens type A. CONCLUSIONS: This study conducted an investigation on the prevalence, distribution, and risk factors associated with Eimeria species infection in broiler chickens in Guangdong. The farm-level prevalence of Eimeria species was higher than the previous prevalence figures for other areas and countries. E. brunetti was identified at higher prevalence in Guangdong than previously survived prevalence in different regions in China. Farm location, chicken age, drinking water source, control strategy, and the presence of C. perfringens type A were considered as potential risk factors associated with prevalence of Eimeria species. It is imperative to underscore the necessity for further surveys to delve deeper into the occurrence of Eimeria species under intensive management conditions for different flock purposes.

Molecular characterization of chicken infectious anaemia virus (CIAV) in China during 2020-2021.

Chicken infectious anaemia virus (CIAV) has been identified as the causative agent of chicken infectious anaemia (CIA), causing huge economic losses to the poultry industry globally. In this study, a total of 573 clinical samples were collected from 197 broiler farms in 17 provinces of China during 2020-2021. Among them, 375 samples (375/573, 65.4%) were positive for CIAV by real-time PCR. The positive rate of CIAV detection between different regions of China ranged from 46.67% (North China) to 81.25% (Central China). The nucleotide sequences of the VP1 gene were obtained for 91 CIAV strains, whole genome sequencing was successful for 72 out of 91 strains. Phylogenetic analysis based on the VP1 gene revealed that 91 CIAV strains currently circulating in China belong to three genotypes (II, IIIa and IIIb), and most of the CIAV strains belong to genotype IIIa. Phylogenetic analysis of the whole genome showed that 71 CIAV strains belong to genotype IIIa, and one strain belongs to genotype II. Sequence analysis showed several amino acid substitutions in both the VP1, VP2 and VP3 proteins. Our results enhance the understanding of the molecular characterization of CIAV infection in China.RESEARCH HIGHLIGHTS A molecular systematic survey of CIAV in China during 2020-2021.CIAV genotype IIIa is the predominant genotype in China.

Epidemiological investigation of duck adenovirus 3 in southern China, during 2018-2020.

RESEARCH HIGHLIGHTSFirst report of the epidemiology of duck adenovirus 3 infection in China.Mutant DAdV-3 strains (truncated ORF67) became predominant.

Characterization and pathogenicity of a novel avian nephritis virus isolated in China.

ABSTRACTAvian nephritis virus infections of chicken flocks cause enteric and kidney disease, uneven growth, and runting stunting syndrome, leading to economic losses in the poultry industry. In this study, one ANV strain, designated as AH202017, was isolated from a diseased broiler flock in Anhui province, China, in 2020. Virus production in LMH cell culture was confirmed by real-time RT-PCR and immunofluorescence assay. The complete genome sequencing analysis indicated that AH202017 shares 77.5-85.5% identity with 12 reference strains in GenBank. Phylogenetic analysis of the capsid protein revealed that AH202017 is more closely related to VIC-6a/Australia/2014 belonging to ANV genotype 2. However, the phylogenetic tree, based on the ORF1a protein and ORF1b protein, indicated that AH202017 manifests a close relationship with GXJL815/China/2017 belonging to genotype 8. In infection experiments, four infected chickens showed depression and one chicken died at 6 days post-infection, corresponding to 5% mortality. The virus was shed daily in the faeces of infected chickens, and was found distributed in multiple organs. Macroscopic and microscopic lesions in the kidneys were observed. This is the first paper that describes the genomic characteristics and pathogenicity of a novel ANV strain in China. RESEARCH HIGHLIGHTSA novel ANV strain was isolated for the first time from diseased broilers in China.The ANV strain caused nephritis and 5% mortality rate in 1-day-old SPF chickens.

Prevalence and diversity of Trichomonas gallinae in meat pigeons (Columba livia) in Guangdong Province, People's Republic of China.

Pigeon farming for meat has developed into an important economic industry in most countries, especially in China. Trichomoniasis, caused by the protozoan parasite Trichomonas gallinae, is a worldwide disease in pigeons. However, studies of the prevalence and distribution of T. gallinae lineages in domestic pigeons in southern China are limited. In this study, a total of 636 pigeon throat swabs samples from four regions in Guangdong Province were screened for T. gallinae by in vitro culture assays and microscopy. The results revealed an overall prevalence of T. gallinae infection in southern China of 26.6% (169/636). There were significant differences in the infection rate of T. gallinae between the four regions (χ2 = 117.948, df = 4, P = 0.000), with up to 44.6% in the Pearl River Delta region. The infection rate of young pigeons was as high as 70.8%. The rDNA sequences (18S rRNA/ITS1-5.8S rRNA-ITS2) of 153 positive samples were amplified and sequenced. Results identified 58.2% (89/153) overall as ITS-A (18S-VI) (also known as ITS-OBT-Tg-1) and 41.8% (64/153) as ITS-B (18S-IV) (also known as ITS-OBT-Tg-2). Thus, ITS-A (18S-VI) was the dominant T. gallinae genotype in southern China, especially in young pigeon (97.0%, 32/33). In conclusion, a high prevalence of T. gallinae infection in domestic pigeons was identified in southern China, particularly in the Pearl River Delta region. The ITS-A (18S-VI) was the dominant genotype highly pathogenic, which may weaken the immune system of pigeons, and cause a negative impact on the development of the pigeon industry in China.

Characterization of Pasteurella multocida isolated from ducks in China from 2017 to 2019.

Pasteurella multocida, an important gram-negative pathogen that mainly inhibits the upper respiratory tracts of domestic and wild animals such as chicken, duck, cattle and pig, which can cause cholera fowl, haemorrhagic septicaemia and infectious pneumonia. Currently, the prevalence and infection of P.multocida is still one of the most serious threats to the poultry industry in China, but studies on its characteristics are still insufficient. Here, this study was conducted to isolate and identify P.multocida in infected ducks and determined the leading serotypes and epidemiology of the diseases this pathogen causes. Results indicated that all the isolates were positive for KMT1 gene and the PCR amplified products were approximately 460 bp, demonstrating that these strains were all P.multocida. Moreover, all the isolated strains were identified as capsular type A and lipopolysaccharide type L1. Virulence factor identification results revealed that all strains possessed genes related to pili, adhesin, iron metabolism and uptake. In contrast, toxin coding gene (toxA) and sialidase encodes genes (nan B and nan H) were not detected in any isolates. The drug susceptibility results indicated that all the isolates were resistant to Lincomycin, Chloramphenicol, Clindamycin and Oxacillin but were sensitive to Ceftriaxone and Cefalotin. The animal experiments were also performed to further determine the pathogenicity of these isolated strains. Animal experiment revealed that the liver, kidney, and heart of infected ducks were swollen and had bleeding spots. We also observed hepatocyte hypertrophy, hepatic sinus congestion and single-cell infiltration in infected ducks through H&E staining. In summary, this study demonstrated that all the isolated strains belong to capsular A and lipopolysaccharide type L1 P.multocida, but their virulence factors, drug resistance and pathogenicity were different.

Isolation and characterization of a recombinant Muscovy duck parvovirus circulating in Muscovy ducks in South China.

In 2019, flocks of Muscovy ducks presented with clinical signs typical of MDPV infection. The MDPV GD201911 strain was isolated by inoculating samples from positive birds into Muscovy duck embryos. Challenge with the isolate GD201911 caused typical MDPV disease symptoms and resulted in 25%-40% mortality, depending on the challenge dose, indicating the high pathogenicity of GD201911 for Muscovy ducks. Genome sequencing and phylogenetic analysis demonstrated that GD201911 clustered with recombinant MDPV strains, indicating that recombinant MDPV is circulating in China. Epidemiological monitoring should be performed continuously to assist with decision making for disease control.

Epidemiology, molecular characterization, and recombination analysis of chicken anemia virus in Guangdong province, China.

Chicken anemia virus (CAV) causes severe anemia and immunosuppression in young chickens and a compromised immune response in older birds, resulting in great economic losses to the poultry industry worldwide. Here, we report the molecular epidemiology and characterization of CAV circulating in poultry in Guangdong province, China. Ninety-one of 277 chickens collected from 2016 to 2017 were CAV positive. Full-genome sequencing revealed the presence of eight separate strains. Phylogenetic analysis based on the genome sequences obtained in this study and related sequences available in the GenBank database showed that all of the CAV isolates exhibit a close relationship to each other and belong to the same genotypic group. Putative recombination events were also detected in the genomes of the newly isolated CAVs. Collectively, our findings underscore the importance of CAV surveillance and provide information that will lead to a better understanding of the evolution of CAV.

Sequence and phylogenetic analysis of surface protein genes of emerging H9N2 influenza viruses isolated from poultry in two geographical regions of China.

Subtype H9N2 avian influenza viruses (AIVs) circulating in China have aroused increasing concerns for their impact on poultry and risk to public health. The present study was an attempt to elucidate the phylogenetic relationship of H9N2 AIVs in two geographically distinct regions of China where vaccination is routinely practiced. A total of 18 emerging H9N2 isolates were identified and genetically characterized. Phylogenetic analysis of hemagglutinin (HA) and neuraminidase (NA) genes confirmed that the isolates belonged to the Y280 lineage. Based on the HA genes, the isolates were subdivided into two subgroups. The viruses from Zhejiang Province were clustered together in Group I, while the isolates from Guangdong Province were clustered together in Group II. Antigenic characterization showed that the tested viruses were antigenically different when compared to the current used vaccine strain. It was notable that 14 out of total 18 isolates had an amino acid exchange (Q→L) at position 216 (226 by H3 Numbering) in the receptor-binding site, which indicated that the virus had potential affinity of binding to human like receptor. These results suggest that the emerging viruses have potential risk to public health than previously thought. Therefore, continuous surveillance studies of H9N2 influenza virus are very important to the prognosis and control of future influenza pandemics.

Recombinant linear multiple epitopes of σB protein protect Muscovy ducks against novel duck reovirus infection.

Infection by the novel duck reovirus (NDRV) in ducklings causes high mortality, which leads to substantial economic losses in the duck industry in China. To date, no commercial vaccine is available for this disease. In this study, linear B cell epitopes of the σB protein of the NDRV were predicted and recombinant multiple linear B cell epitopes (MLBEs) were constructed through linkers. The recombinant MLBEs were then expressed and purified. One-day-old Muscovy ducklings were immunized with different doses of MLBEs and challenged with 5 × 104 ELD50 of the virulent CHY strain of NDRV 14 days after immunization. The ducklings vaccinated with 20 and 40 µg of MLBE performed no clinical signs or gross or histopathological lesions, indicating 100% protection against infection. The viral load in the liver and spleens of these birds was significantly lower than that in the control group. Additionally, these ducklings exhibited positive seroconversion at 7 days after vaccination on enzyme-linked immunosorbent assay. These results indicate that MLBE of σB could be used as a candidate for developing vaccines against NDRV infection.

Impact of duck astrovirus on susceptibility to infection across duck ages.

An outbreak of duck astrovirus (DAstV) has occurred in duck farming regions of China, causing substantial economic setbacks in the duck industry. This investigation aimed to examine the variations in DAstV pathogenicity among ducks at different age intervals. Infections were induced in ducks at distinct age groups (1, 7, 14, 21, and 28 d) utilizing the DAstv-1-GDB-2022 strain. The results indicate increased pathogenicity of the DAstv-1-GDB-2022 strain in ducklings aged 21 to 28 d, manifesting as liver and kidney enlargement, severe bleeding, and potential fatalities. Conversely, ducklings aged 1 and 14 d displayed milder symptoms postinfection. Notably, viral shedding continued in ducks of diverse age groups even 21 d postinfection (Dpi). Moreover, DAstV replicates in various tissues, predominantly affecting the liver. Immunohistochemical tests using rabbit anti-DAstV antibodies revealed robust positive signals in both the liver and kidneys, which correlated with the clinical symptom severity observed through macroscopic and microscopic examinations. Serum biochemical assays and indirect ELISA demonstrated a consistent response to DAstV infection across different age groups, with older ducklings exhibiting increased sensitivity. In conclusion, this study successfully replicated clinical symptoms similar to those of natural DAstV infection using the DAstv-1-GDB-2022 strain. Importantly, we systematically delineated the differences in susceptibility to DAstV among ducks at various ages, laying the foundation for further research into the pathogenic mechanisms of DAstV and potential vaccine development.

Development of a rapid quantitative method to differentiate MS1 vaccine strain from wild-type Mycoplasma synoviae.

Mycoplasma synoviae (MS) is an economically important pathogen in the poultry industry. Vaccination is an effective method to prevent and control MS infections. Currently two live attenuated MS vaccines are commercially available, the temperature-sensitive MS-H vaccine strain and the NAD-independent MS1 vaccine strain. Differentiation of vaccine strains from wild-type (WT) strains is crucial for monitoring MS infection, especially after vaccination. In this study, we developed a Taqman duplex real-time polymerase chain reaction (PCR) method to identify MS1 vaccine strains from WT strains. The method was specific and did not cross-react with other avian pathogens. The sensitivity assay indicated that no inhibition occurred between probes or between mixed and pure templates in duplex real-time PCR. Compared with the melt-based mismatch amplification mutation assay (MAMA), our method was more sensitive and rapid. In conclusion, the Taqman duplex real-time PCR method is a useful method for the diagnosis and differentiation of WT-MS and MS1 vaccine strains in a single reaction.

The biological characteristics of DAstV molecular epidemiology and pathogenicity of duck astrovirus causing hepatitis in ducks and chickens in Southeast China.

A suspected outbreak of duck astrovirus (DAstV) disease occurred in a large Muscovy duck farm in Guangdong Province, China, in June 2022, which severely affected the production performance and health of Muscovy ducks. This study aimed to investigate the prevalence of DAstV disease in Southeast China. Herein, we employed semi-nested PCR ethodto screen 5203 swab and liver samples from 11 Muscovy duck farms in 5 provinces of China for the presence of DAstV. Among them, 1356 samples (26.06%, 1356/5203) tested positive for DAstV, out of which 11 DAstV strains were isolated after 10 generations of blind transmission through Leghorn male hepatoma (LMH) cells and performed their whole-genome sequencing. The alignment results showed that the 11 DAstV isolates exhibited relatively low homology (15.4%-75%) with the astrovirus isolates from other species published in GenBank, whereas their homology (nucleotide: 90.4%-99.99%; amino acid: 94%-99.8%) with the DAstV type 1 (DAstV-1) reference strain was higher, indicating considerable homology. The results indicated that DAstV-1 was the main pathogenic factor. Herein, we successfully recreated the clinical symptoms of natural infection in 28-day-old specific-pathogen-free (SPF) ducks using the DAstV-1-GDB-2022 strain. The primary clinical manifestations included liver enlargement, hemorrhaging, and disruptions in liver function. Additionally, we confirmed the cross-species transmission potential of DAstV-1, marking the first occurrence of clinical symptoms of DAstV in 28-day-old SPF chickens. Our findings provide new perspectives on the epidemiology and pathogenicity of DAstV-1 and may help in advancing the development of DAstV vaccines.

Alleviating Pentatrichomonas hominis-induced damage in IPEC-J2 cells: the beneficial influence of porcine-derived lactobacilli.

Pentatrichomonas hominis is a common intestinal parasitic protozoan that causes abdominal pain and diarrhea, and poses a zoonotic risk. Probiotics, known for enhancing immunity and pathogen resistance, hold promise in combating parasitic infections. This study aimed to evaluate two porcine-derived probiotics, Lactobacillus reuteri LR1 and Lactobacillus plantarum LP1, against P. hominis infections in pigs. Taxonomic identity was confirmed through 16 S rRNA gene sequencing, with L. reuteri LR1 belonging to L. reuteri species and L. plantarum LP1 belonging to L. plantarum species. Both probiotics exhibited robust in vitro growth performance. Co-culturing intestinal porcine epithelial cell line (IPEC-J2) with these probiotics significantly improved cell viability compared with the control group. Pre-incubation probiotics significantly enhanced the mRNA expression of anti-oxidative response genes in IPEC-J2 cells compared with the PHGD group, with L. reuteri LR1 and L. plantarum LP1 significantly up-regulating CuZn-SOD、CAT and Mn-SOD genes expression (p < 0.05). The anti-oxidative stress effect of L. reuteri LR1 was significantly better than that of L. plantarum LP1 (p < 0.05). Furthermore, pre-incubation with the probiotics alleviated the P. hominis-induced inflammatory response. L. reuteri LR1 and L. plantarum LP1 significantly down-regulated IL-6、IL-8 and TNF-α gene expression(p < 0.05) compared with the PHGD group. The probiotics also mitigated P. hominis-induced apoptosis. L. reuteri LR1 and L. plantarum LP1 significantly down-regulated Caspase3 and Bax gene expression (p < 0.05), significantly up-regulated Bcl-2 gene expression (p < 0.05) compared with the PHGD group. Among them, L. plantarum LP1 showed better anti-apoptotic effect. These findings highlight the probiotics for mitigating P. hominis infections in pigs. Their ability to enhance anti-oxidative responses, alleviate inflammation, and inhibit apoptosis holds promise for therapeutic applications. Simultaneously, probiotics can actively contribute to inhibiting trichomonal infections, offering a novel approach for preventing and treating diseases such as P. hominis. Further in vivo studies are required to validate these results and explore their potential in animal and human health.

Genotypic diversity and epidemiology of Trichomonas gallinae in Columbidae: Insights from a comprehensive analysis.

Trichomonas gallinae is a protozoa that parasitizes the upper gastrointestinal and respiratory tracts of various animals and birds, including Columbidae, Passeriformes, and Falconiformes. Polymerase chain reaction-based T. gallinae ITS1/5.8S/ITS2 gene typing yields inconsistent results owing to methodological differences. To standardize the statistical analysis of T. gallinae genotype distributions, this study employed MEGA-X software with the Tamamura 3-parameter (T92) + G model in the neighbor-joining method, with 2,000 bootstrap replicates, to calculate a systematic evolutionary tree. The resulting tree comprised 12 branches, ITS-OBT-Tg-1 to ITS-OBT-Tgl, with similar phylogenetic relationships. Relevant literature review yielded T. gallinae prevalence data in Columbidae. Statistical analysis was conducted from two perspectives: non-biological and biological factors, using chi-square tests and ordered logistic regression analysis. T. gallinae positivity rates differed significantly across diverse regions (χ2 = 4,609.9, P = 0.000, df = 4) and at various times (χ2 = 2,810.8, P = 0.000, df = 3). However, temperature and precipitation did not significantly affect T. gallinae positivity rates. Additionally, T. gallinae positivity rates differed significantly among diverse hosts (χ2 = 2,958.6, P = 0.000, df = 14) and by host age (χ2 = 478.5, P = 0.000, df = 2) and sex (χ2 = 96.00, P = 0.000, df = 1). This comprehensive analysis aimed to control T. gallinae transmission, reduce economic and species resource losses, and provide a foundation for future related research.

Unraveling the pathogenic potential of the Pentatrichomonas hominis PHGD strain: impact on IPEC-J2 cell growth, adhesion, and gene expression.

Pentatrichomonas hominis, a flagellated parasitic protozoan, predominantly infects the mammalian digestive tract, often causing symptoms such as abdominal pain and diarrhea. However, studies investigating its pathogenicity are limited, and the mechanisms underlying P. hominis-induced diarrhea remain unclear. Establishing an in vitro cell model for P. hominis infection is imperative. This study investigated the interaction between P. hominis and IPEC-J2 cells and its impact on parasite growth, adhesion, morphology, and cell viability. Co-cultivation of P. hominis with IPEC-J2 cells resulted in exponential growth of the parasite, with peak densities reaching approximately 4.8 × 105 cells/mL and 1.2 × 106 cells/mL at 48 h for initial inoculation concentrations of 104 cells/mL and 105 cells/mL, respectively. The adhesion rate of P. hominis to IPEC-J2 cells reached a maximum of 93.82% and 86.57% at 24 h for initial inoculation concentrations of 104 cells/mL and 105 cells/mL, respectively. Morphological changes in IPEC-J2 cells co-cultivated with P. hominis were observed, manifesting as elongated and irregular shapes. The viability of IPEC-J2 cells exhibited a decreasing trend with increasing P. hominis concentration and co-cultivation time. Additionally, the mRNA expression levels of IL-6, IL-8, and TNF-α were upregulated, whereas those of CAT and CuZn-SOD were downregulated. These findings provide quantitative evidence that P. hominis can promote its growth by adhering to IPEC-J2 cells, inducing morphological changes, reducing cell viability, and triggering inflammatory responses. Further in vivo studies are warranted to confirm these results and enhance our understanding of P. hominis infection.

Title: Découvrir le potentiel pathogène de la souche PHGD de Pentatrichomonas hominis : impact sur la croissance, l'adhésion et l'expression des gènes des cellules IPEC-J2. Abstract: Pentatrichomonas hominis, un protozoaire parasite flagellé, infecte principalement le tube digestif des mammifères, provoquant souvent des symptômes tels que des douleurs abdominales et de la diarrhée. Cependant, les études portant sur sa pathogénicité sont limitées et les mécanismes sous-jacents à la diarrhée induite par P. hominis restent flous. L'établissement d'un modèle cellulaire in vitro de l'infection à P. hominis est impératif. Cette étude a examiné l'interaction entre P. hominis et les cellules IPEC-J2 et son impact sur la croissance du parasite, l'adhésion, la morphologie et la viabilité cellulaire. La co-culture de P. hominis avec des cellules IPEC-J2 a entraîné une croissance exponentielle du parasite, avec des densités maximales atteignant environ 4,8 × 105 cellules/mL et 1,2 × 106 cellules/mL à 48 h pour des concentrations d'inoculation initiales de 104 cellules/mL et 105 cellules/mL, respectivement. Le taux d'adhésion de P. hominis aux cellules IPEC-J2 a atteint un maximum de 93,82 % et 86,57 % après 24 h pour des concentrations d'inoculation initiales de 104 cellules/mL et 105 cellules/mL, respectivement. Des changements morphologiques dans les cellules IPEC-J2 co-cultivées avec P. hominis ont été observés, se manifestant par des formes allongées et irrégulières. La viabilité des cellules IPEC-J2 a montré une tendance à la baisse avec l'augmentation de la concentration de P. hominis et de la durée de co-culture. De plus, les niveaux d'expression d'ARNm d'IL-6, d'IL-8 et de TNF-α étaient régulés positivement, tandis que ceux de CAT et de CuZn-SOD étaient régulés négativement. Ces résultats fournissent des preuves quantitatives que P. hominis peut favoriser sa croissance en adhérant aux cellules IPEC-J2, en induisant des changements morphologiques, en réduisant la viabilité cellulaire et en déclenchant des réponses inflammatoires. D'autres études in vivo sont nécessaires pour confirmer ces résultats et améliorer notre compréhension de l'infection à P. hominis.

Epidemiological investigation of coccidiosis and associated risk factors in broiler chickens immunized with live anticoccidial vaccines in China.

Coccidiosis is a costly intestinal disease of chickens caused by Eimeria species. This infection is associated with high mortality, reduced feed efficiency, and slowed body weight gain. The diagnosis and control of coccidiosis becomes challenging due to the fact that chickens can be infected by seven different Eimeria species and often occur mixed-species co-infections. Grasping the epidemiology of Eimeria species is crucial to estimate the efficiency of poultry management. This study aimed to explore the distribution of Eimeria species in broiler chickens in China after administering live anticoccidial vaccines. A total of 634 samples were obtained, and the survey results showed that the prevalence of Eimeria was 86.12% (546/634), and the most common species were E. acervulina (65.62%), E. necatrix (50.95%), E. mitis (50.79%), E. tenella (48.42%), and E. praecox (41.80%). Most samples indicated mixed-species infections (an average of 3.29 species per positive sample). Notably, 63.98% of samples contain 3 to 5 Eimeria species within a single fecal sample. The most prevalent combinations were E. acervulina-E. tenella (38.96%) and E. acervulina-E. necatrix (37.22%). Statistical analysis showed that flocks vaccinated with trivalent vaccines were significantly positive for E. necatrix in grower chickens (OR = 3.30, p < 0.05) compared with starter chickens, and tetravalent vaccinated flocks showed that starter chickens demonstrated a higher susceptibility to E. tenella-E. brunetti (OR = 2.03, p < 0.05) and E. acervulina-E. maxima (OR = 2.05, p < 0.05) compared with adult chickens. Geographically, in the case of tetravalent vaccine-immunized flocks, a substantial positive association was observed between E. necatrix infection rates and flocks from eastern (OR = 3.88, p < 0.001), central (OR = 2.65, p = 0.001), and southern China (OR = 3.17, p < 0.001) compared with southwestern China. This study also found a positive association between E. necatrix (OR = 1.64, p < 0.05), E. acervulina (OR = 1.59, p < 0.05), and E. praecox (OR = 1.81, p < 0.05) infection and coccidiosis occurrence compared with non-infected flocks in tetravalent vaccinated flocks. This molecular epidemiological investigation showed a high prevalence of Eimeria species in the field. The emergent species, E. brunetti and E. praecox, might be incorporated into the widely-used live vaccines in the future. These insights could be useful in refining coccidiosis control strategies in the poultry industry.

Selection of a suitable reference gene for gene-expression studies in Trichomonas gallinae under various biotic and abiotic stress conditions.

Trichomonas gallinae, a globally distributed protozoan parasite, significantly affects the pigeon-breeding industry. T. gallinae infection mainly causes yellow ulcerative nodules on the upper respiratory tract and crop mucosa of pigeons, impeding normal breathing and feeding and ultimately causing death. Real-time quantitative PCR (qPCR) is a crucial technique for gene-expression analysis in molecular biology. Reference-gene selection for normalization is critical for ensuring this technique's accuracy. However, no systematic screening or validation of T. gallinae reference genes has been reported. This study quantified the transcript levels of ten candidate reference genes in T. gallinae isolates with different genotypes and culture conditions using qPCR. Using the geNorm, NormFinder, and BestKeeper algorithms, we assessed these reference genes' stabilities and ranked them using RankAggreg analysis. The most stable reference gene was tubulin beta chain (TUBB), while the widely used reference genes TUBG and GAPDH demonstrated poor stability. Additionally, we evaluated these candidate reference genes' stabilities using the T. gallinae TgaAtg8 gene. On using TUBB as a reference gene, TgaAtg8's expression profiles in T. gallinae isolates with different genotypes remained relatively consistent under various culture conditions. Conversely, using ACTB as a reference gene distorted the data. These findings provide valuable reference-gene-selection guidance for functional gene research and gene-expression analysis in T. gallinae.

Complete genome sequence analysis of a natural reassortant infectious bursal disease virus in China.

A novel isolate of infectious bursal disease virus (IBDV) was designated GX-NN-L. The GX-NN-L IBDV was a very virulent infectious bursal disease virus (vvIBDV) isolated from broiler flocks in Guangxi province, China, in 2011. The GX-NN-L IBDV caused high mortality, immunosuppression, low weight gain, and bursal atrophy in commercial broilers. Here, we report the complete genome sequence of the GX-NN-L IBDV, a reassortment strain with segments A and B derived from very virulent strains and attenuated IBDV, respectively. These findings from this study provide additional insights into the genetic exchange between attenuated and very virulent strains of IBDV and continuous monitoring of the spread of the virus in chicken.

Complete genome sequence of a recombinant nephropathogenic infectious bronchitis virus strain in China.

Recently, nephropathogenic infectious bronchitis virus (IBV) outbreaks have occurred in commercial broiler flocks and have been associated with a high incidence and morbidity in China. The CK/CH/Zhejiang/06/10 strain (IBV-YX10) was isolated from a 12-day-old broiler chicken in a flock of chickens with swollen speckled kidneys and distended ureters filled with uric acid in China in 2010. Here we reported the complete genomic sequence of the IBV-YX10 which was a natural recombinant nephropathogenic infectious bronchitis virus strain. These findings will contribute additional insights into the molecular characteristics of evolving IBV genomes and the need for effective control of IBV in China.