Qingmei Xie

The combination of deoxynivalenol and zearalenone at permitted feed concentrations causes serious physiological effects in young pigs

This study was to investigate the effects of the combination of deoxynivalenol (DON) and zearalenone (ZON) on pigs. Twenty-four weaning piglets were divided into a control group fed a diet free of mycotoxins and a toxin group fed a diet containing 1 mg/kg DON and 250 µg/kg ZON. The results showed that supplementation of DON and ZON in diets had extensive effects on pigs. More specifically, DON and ZON caused levels of total protein, albumin, and globulin in sera to decrease (p < 0.05) by 14.5%, 6.5% and 11.3%, respectively, and at the same time increased (p < 0.05) the serum enzyme activities of γ-glutamyltransferase, aspartate aminotransferase and alanine aminotransferase by 72.0%, 32.6% and 36.6%, respectively. In addition, DON and ZON decreased (p < 0.05) the level of anti-classical swine fever antibody titers by 14.8%. Real-time PCR showed that DON and ZON caused the mRNA expression levels of IFN-γ, TNF-α, IL-2, to decrease (p < 0.05) by 36.0%, 29.0% and 35.4%, respectively. Histopathological studies demonstrated that DON and ZON caused abnormalities in the liver, spleen, lymph nodes, uterus, and kidney. The concentrations of DON and ZON used in this study are in line with the published critical values permitted by BML. Our study clearly put the standard and adequacy of safety measures for these toxins into question. The authors suggest that with the increasing availability of cellular and molecular technologies, it is time to revisit the safety standards for toxins in feeds so as to make feeds safer, providing consumers with safer products.

ISOLATION AND GENETIC ANALYSIS REVEALED NO PREDOMINANT NEW STRAINS OF AVIAN INFECTIOUS BRONCHITIS VIRUS CIRCULATING IN SOUTH CHINA DURING 2004-2008

Abstract Twenty-seven strains of avian infectious bronchitis virus (IBV) were isolated from dead or diseased chickens at different chicken farms in South China during 2004–2008, of which the S1 gene was sequenced. Phylogenetic analysis of the S1 gene sequences of the isolated 27 strains together with 29 strains published in Genbank revealed that all IBV strains except for one isolated and one published were clustered into six distinct genotypes I-VI. 26 isolated strains belong to genotypes I, II, and III, forming a big phylogenetic branch without new predominant strains, whereas all five vaccine strains belong to genotype V that is evolutionarily distant from genotypes I, II, and III. The study of the protease cleavage motif within the S1 protein found 12 different cleavage motifs, of which 3 motifs are shared by both isolated and published strains, 2 motifs unique to isolated strains, and 7 motifs unique to published strains, further bolstering the notion of no new predominant strains. Alignment analysis of the S1 amino acid sequences indicated that the amino acid substitutions, insertions, and deletions are polymorphic and diverse, showing no sign of predominant genetic changes among the isolated strains. Taken together, there was no predominant new strain circulating in South China during 2004–2008. Nonetheless, circulating IBV strains have been continuously evolving with genetic compositions distant from vaccine strains; this explains why there have been constant but infrequent outbreaks in commercial flocks in South China during 2004–2008. Furthermore, in order to safe guard against the sudden emergence of new predominant strains, continuing surveillance of IBV strains circulating in the field is of extreme importance.

Phylogenetic distribution and predominant genotype of the avian infectious bronchitis virus in China during 2008-2009.

BackgroundThe nephropathogenic avian infectious bronchitis (IB) caused unprecedented economic losses to the commercial chicken industry of China in 2008-2009. To investigate the prevalence of nephropathogenic IB in China, eighty IBV isolates from different provinces during 2008-2009 were identified by dwarf embryo test and RT-PCR.ResultsThe strains were mostly isolated in winter and spring with a wide age range of IB outbreaks, from 4 to 69 days. By the virus recovery trials, 70/80 of the strains resulted in the deaths or distresses of birds from nephritis. To learn more about the molecular evolutionary characteristics of the circulating field strains, the coding region of major spike 1 (S1) protein gene of these strains was RT-PCR amplified and sequenced. Compared to the published representative strains, nucleotides and amino acids sequence analysis indicated that the S1 genes of these strains and the reference strains displayed homologies ranging from 75.1% to 99.8% and from 73.1% to 99.8% respectively. S1 protein of the major pandemic strains contained 540 or 542 amino acids with the cleavage site of HRRRR or RRFRR. Phylogenetic analysis revealed that recent field isolates of IBV in China were mostly belonged to A2-branch (QXIBV-branch) and HN08-branch, only one isolate was belonged to Gray-branch and M41-branch respectively. Most of the 80 strains showed evolutionarily distant from vaccine strains.ConclusionsThe results of this study suggested that nephropathogenic IBVs were mainly A2-like strains in China during 2008-2009.

Astragalus polysaccharide enhances immunity and inhibits H9N2 avian influenza virus in vitro and in vivo

This study investigated the humoral immunization of Astragalus polysaccharide (APS) against H9N2 avian influenza virus (H9N2 AIV) infection in chickens.The effects of APS treatment on H9N2 infection was evaluated by an MTT [3(4, 5-dimethylthiazol-2-yl)-2, 3-diphenyl tetrazolium bromide] assay and analysis of MHC and cytokine mRNA expression. The effect on lymphocyte and serum antibody titers in vivo was also investigated. IL-4, IL-6, IL-10, LITAF, IL-12 and antibody titers to H9N2 AIV were enhanced in the first week after APS treatment. The results indicated that APS treatment reduces H9N2 AIV replication and promotes early humoral immune responses in young chickens.

Complete genomic characterization of a Chinese isolate of porcine reproductive and respiratory syndrome virus

The genome of one isolate of porcine reproductive and respiratory syndrome virus (PRRSV) from China, designated GDQY2, was sequenced and analyzed. The full length of GDQY2 was 15,215 nucleotides, excluding the poly(A) tail. Comparative analysis with the genomic sequences of numerous worldwide North American isolates revealed that GDQY2 shared 85.0-98.9% identity with these isolates, but only 60.9% with the European virus-LV (Lelystad Virus), indicating that this new Chinese isolate was closely related to the North American PRRSV genotype. Phylogenetic analysis based on the nucleotide sequences of the full length and ORF5 showed that this new isolate belong to the same genetic group with all other Chinese isolates. Comparison with North American PRRSV isolates revealed that GDQY2 exhibited variations in the non-structural protein 2 (NSP2) encoded by ORF1a, namely that an additional 35-amino acid deletion in NSP2 was found in GDQY2. Therefore, GDQY2 was a novel strain with unique deletions. Furthermore, our study demonstrated that North American genotype PRRSVs in China have evolved independently from other countries, indicating that geographic separation might be one factor influencing the molecular evolution of PRRSV.

Molecular detection of Muscovy duck parvovirus by loop-mediated isothermal amplification assay

Muscovy duck parvovirus (MDPV) usually causes high morbidity and mortality in 1- to 3-wk-old Muscovy ducklings due to serious infections, which is an imminent threat to the commercial duck industry in China. The objectives of this study were to develop and evaluate a simple, rapid, and inexpensive loop-mediated isothermal amplification (LAMP) method for specific detection of MDPV and to compare it with the PCR method in rapidity, sensitivity, and accuracy. The novel LAMP assay used a set of 4 specific primers to recognize 6 distinct genomic sequences of capsid protein (VP3) from MDPV, which could be completed within 50 min at 63 degrees C in a simple water bath. The diagnostic results demonstrated that the LAMP assay detected all 7 preserved MDPV isolates, had no cross-reactivity with other duck pathogens (i.e., goose parvovirus, duck plague virus, H9N2 avian influenza virus, duck hepatitis type virus I, and Muscovy duck reovirus). The LAMP assay was at least 10-fold more sensitive than the routine PCR assay and obtained more sensitivity in 61 clinical samples. Therefore, the newly developed LAMP assay provides a specific and sensitive means for detecting MDPV and can be simply applied both in field conditions and in laboratory operations in a cost-effective manner with primary care facilities.

The First Identification and Complete Genome of Senecavirus A Affecting Pig with Idiopathic Vesicular Disease in China.

Senecavirus A (SVA) infection was recently confirmed in pigs in Brazil. In March, 2015, an outbreak of vesicular disease occurred in Guangdong, China, characterized by vesicular lesions in sows and acute death of neonatal piglets. Cumulative incidence of porcine idiopathic vesicular disease in farm A was 258, which had a total number of 5500 sows. Sows in farm B displayed typical vesicular symptoms by May, 2015, which also had 5500 sows. A total of 278 and 142 of 5500 sows in farm B demonstrated lame and presented vesicles, respectively, associated with a total of 186 mortality in piglets. Routine differential diagnoses for swine vesicular disease were carried out to exclude infection with foot-and-mouth disease virus, swine vesicular disease virus, vesicular exanthema of swine virus and vesicular stomatitis virus. In this study, seven pairs of primer were designed to amplify the complete genome of SVA in RT-PCR assays. Sequence alignment showed that this Chinese strain shares 94.4-97.1% sequence identity to other eight strains of SVA. This is the first report of SVA in China and provides information about the association between SVA infection and vesicular disease.

Different combinations of probiotics improve the production performance, egg quality, and immune response of layer hens

To evaluate the effects of different combinations of probiotics on performance, egg quality, and immune response of layer hens, a trial was carried out with 1,800 white feather layer hens of the Lohmann variety. The experiment was conducted by using a completely randomized design with 9 treatments, 4 replicates, and 50 hens in each replicate. Compared with the control group, group F, which added a composition of heat-inactivated Lactobacillus salivarius(CB) and Bacillus subtilis to the diets of layer hens, caused highly significant (P < 0.05) increases in egg production, daily egg yield, damaged egg ratio, combined with a significant (P < 0.05) decrease in feed conversion and damaged egg ratio. Group G, adding a combination of inactivated Lactobacillus salivarius and sodium butyrate, resulted in a significant increase (P < 0.05) in daily egg yield, feed conversion, damaged egg ratio and Haugh unit. Meanwhile, groups D and H had significantly decreased feed conversion (P < 0.05), and groups B, H, and I had a significantly decreased damaged egg ratio. In serum levels, no significant difference was observed except a significant decrease (P < 0.05) in total cholesterol (groups D, E, and G) and low-density lipoprotein cholesterol (group E and G) and a significant increase (P < 0.05) in total cholesterol (groups D, E, and G) compared with group A. According to the hemagglutination inhibition test, the antibody titer of antibody against the avian influenza virus was significantly (P < 0.05) higher in most treated groups such as groups B, C, E, G, and I after d 15 fed to layers with probiotics and groups B, C, D, E, F, G, and H after d 45 compared with the control group. No significant difference was observed in the antibody titer against the Newcastle disease virus at d 15, but significantly (P < 0.05) higher at d 45 in groups F and G. These results demonstrate that several combinations of probiotics used in this experiment have a positive impact on the performance, egg quality, and immune response of layer hens, and the following work will continue to focus on these groups.

Phylogenetic analysis of the S1 glycoprotein gene of infectious bronchitis viruses isolated in China during 2009–2010

As part of our ongoing surveillance program, 40 field strains of avian infectious bronchitis virus (IBV) were isolated from dead or diseased chicken flocks in different areas of China between 2009 and 2010. S1 glycoprotein genes of these strains were sequenced and analyzed with 38 strains published in GenBank. S1 genes of these isolated strains and the vaccine strains showed nucleotide homologies ranging from 65.2 to 82% and amino acid homologies ranging from 58.4 to 81.9%. Meanwhile, Chinese IBV strains isolated in this study, which were mainly nephropathogenic, could be separated into six variant lineages (CH I–CH VI), and current vaccine strains used in China formed Mass variant lineage that is evolutionarily distant from Chinese isolates. Moreover, CK/CH/GD/NC10, CK/CH/GD/KP10, and our previous isolates TC07-2 formed the CH VI lineage, showing larger evolutionary distances from other strains. Taken together, these findings suggested that various variant lineages were co-circulating in China now, and appeared to be continuously evolving, alternative indigenous vaccines indeed need for effective control of IB in China.

The potent adjuvant effects of chicken β-defensin-1 when genetically fused with infectious bursal disease virus VP2 gene

Defensins are fundamental components of innate immune response. Current data favor that defensins play vital roles on both innate and adaptive immune responses. The aim of the present study was to investigate whether the chicken beta-defensin-1 (also named avian beta-defensin-1, AvBD1) has the potent adjuvant effects on DNA vaccine encoding IBDV VP2 gene, when genetically fused with VP2 gene. The recombinant vectors pcDNA3.1(+)-VP2 and pcDNA3.1(+)-AvBD1-VP2 were constructed as the DNA vaccines. Four groups of 14-day-old chickens were intramuscularly injected with PBS buffer, empty vector pcDNA3.1(+), recombinant pcDNA3.1(+)-VP2 and pcDNA3.1(+)-AvBD1-VP2. Results showed that VP2-specific antibody levels significantly increased following two recombinant DNA vaccine administrations (p<0.05), compared with the group of PBS and empty vector. The antibody level of group immunized with pcDNA3.1(+)-AvBD1-VP2 was significantly higher than that of group immunized with pcDNA3.1(+)-VP2 after second vaccination (p<0.05). The percentages of CD3+, CD4+ and CD8+ T-cell subtypes between groups of pcDNA3.1(+)-VP2 and pcDNA3.1(+)-AvBD1-VP2 obtained significantly different (p<0.05), the latter was higher, at 7 days post-booster. The protection from IBD challenged by immunized chickens with DNA vaccines encoding IBDV VP2 gene alone was lower than that by immunized IBDV VP2 gene together with AvBD1 gene. The results indicated that AvBD1 has an adjuvant effects on improvement the IBDV VP2-DNA vaccine effectiveness.