Metagenomics to Identify Viral Communities Associated with Porcine Respiratory Disease Complex in Tibetan Pigs in the Tibetan Plateau, China.

Tibetan pig is a unique pig breed native to the Qinghai-Tibet Plateau. To investigate viral communities associated with porcine respiratory disease complex (PRDC), 167 respiratory samples were collected from Tibetan pigs in the Ganzi Tibetan autonomous prefecture of Sichuan province. Following library construction and Illunima Novaseq sequencing, 18 distinct viruses belonging to 15 viral taxonomic families were identified in Tibetan pigs with PRDC. Among the 18 detected viruses, 3 viruses were associated with PRDC, including porcine circovirus type 2 (PCV-2), Torque teno sus virus (TTSuV), and porcine cytomegalovirus (PCMV). The genomic sequences of two PCV-2 strains, three TTSuV strains, and one novel Porprismacovirus strain were assembled by SOAPdenovo software (v2). Sequence alignment and phylogenetic analysis showed that both PCV-2 strains belonged to PCV-2d, three TTSuVs were classified to TTSuV2a and TTSuV2b genotypes, and the Porprismacovirus strain PPMV-SCgz-2022 showed a close genetic relationship with a virus of human origin. Recombination analysis indicated that PPMV-SCgz-2022 may have originated from recombination events between Human 16,806 × 66-213 strain and Porcine 17,668 × 82-593 strain. Furthermore, the high proportion of single infection or co-infection of PCV2/TTSuV2 provides insight into PRDC infection in Tibetan pigs. This is the first report of the viral communities in PRDC-affected Tibetan pigs in this region, and the results provides reference for the prevention and control of respiratory diseases in these animals.

Neglected Spleen Transcriptional Profile Reveals Inflammatory Disorder Conferred by Rabbit Hemorrhagic Disease Virus 2 Infection.

Rabbit hemorrhagic disease (RHD) is an acute fatal disease caused by the rabbit hemorrhagic disease virus (RHDV). Since the first outbreaks of type 2 RHDV (RHDV2) in April 2020 in China, the persistence of this virus in the rabbit population has caused substantial economic losses in rabbit husbandry. Previous failures in preventing RHDV2 prompted us to further investigate the immune mechanisms underlying the virus's pathogenicity, particularly concerning the spleen, a vital component of the mononuclear phagocyte system (MPS). For this, a previous RHDV2 isolate, CHN/SC2020, was utilized to challenge naive adult rabbits. Then, the splenic transcriptome was determined by RNA-Seq. This study showed that the infected adult rabbits had 3148 differentially expressed genes (DEGs), which were associated with disease, signal transduction, cellular processes, and cytokine signaling categories. Of these, 100 upregulated DEGs were involved in inflammatory factors such as IL1α, IL-6, and IL-8. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that these DEGs were significantly enriched in the cytokine-cytokine receptor interaction signaling pathway, which may play a vital role in CHN/SC2020 infection. At the same time, proinflammatory cytokines and chemokines were significantly increased in the spleen at the late stages of infection. These findings suggested that RHDV2 (CHN/SC2020) might induce dysregulation of the cytokine network and compromise splenic immunity against viral infection, which expanded our understanding of RHDV2 pathogenicity.

Immune modulation of Th1/Th2/Treg/Th17/Th9/Th21 cells in rabbits infected with Eimeria stiedai.

Introduction: Despite long-term integrated control programs for Eimeria stiedai infection in China, hepatic coccidiosis in rabbits persists. Th1, Th2, Th17, Treg, Th9, and Th21 cells are involved in immune responses during pathogen infection. It is unclear whether Th cell subsets are also involved in E. stiedai infection. Their roles in the immunopathology of this infection remain unknown. Therefore, monitoring these T-cell subsets' immune responses during primary infection of E. stiedai at both transcriptional (mRNA) and protein (cytokines) levels is essential. Methods: In experimentally infected New Zealand white rabbits, mRNA expression levels of their transcript-TBX2 (Th1), GATA3 (Th2), RORC (Th17), Foxp3 (Treg), SPI1 (Th9), and BCL6 (Th21)-were evaluated using quantitative real-time polymerase chain reaction (qRT-PCR), whereas Th1 (IFN-g and TNF-a), Th2 (IL4), Th17 (IL17A and IL6), Treg (IL10 and TGF-b1), Th9 (IL9), and Th21 (IL21) cytokines were measured using enzyme-linked immunosorbent assays (ELISAs). Results: We found that levels of TBX2, GATA3, RORC, SPI1, and BCL6 in the livers of infected rabbits were elevated on days 5 and 15 post-infection (PI). The concentrations of their distinctive cytokines IFN-g and TNF-a for Th1, IL4 for Th2, IL17A for Th17, IL9 for Th9, IL21 for Th21, and IL10 for Treg IL10 were also significantly increased on days 5 and 15 PI, respectively (p < 0.05). On day 23 PI, GATA3 with its cytokine IL4, RORC with IL17A, Foxp3 with IL10 and TGF-b1, and SPI1 with IL9 were significantly decreased, but TBX2 with IFN-g and IL6 remained elevated. Discussion: Our findings are the first evidence of Th1/Th2/Treg/Th17/Th9/Th21 changes in E. stiedai-infected rabbits and provide insights into immune regulation mechanisms and possible vaccine development.

Prevalence and multi-locus genotyping of Giardia duodenalis in rabbits from Shaanxi province in northwestern China.

Giardia duodenalis is an important parasite with veterinary and public health significance worldwide. The presence and zoonotic assemblages of G. duodenalis have previously been reported in rabbits. In this study, to understand the infection status of G. duodenalis in rabbits from Shaanxi province, a total of 537 fecal samples were collected from two breeds of rabbits in four age groups (<30 days, 31-90 days, 91-200 days and >200 days) from four geographical origins (Fengxiang, Yangling, Tongchuan, and Shanyang). The presence of G. duodenalis in these samples was assessed using molecular assays based on beta-giardin (bg). The glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) loci were then amplified in the bg-positive samples for multi-locus genotype (MLG) analysis. The total prevalence of G. duodenalis in these rabbits was 3.54% (19/537). Giardia duodenalis infection was found in both breeds of rabbits, and in all farms and age groups, but with no statistically significant differences related to these factors (p > 0.05). Two assemblages, including B and E, were identified, with the former the predominant assemblage detected in both breeds, and in all age groups and farms. Sequence analysis revealed 2 (named as rbg1-2), 1 (named as rtpi1), and 2 (named as rgdh1-2) haplotypes at the gene loci of bg, tpi, and gdh, respectively, forming a multilocus genotype (MLG) of assemblage B (rbg1, rtpi1, and rgdh1). These findings reveal the significant zoonotic potential and genetic diversity of G. duodenalis in rabbits in Shaanxi Province, PR China.

Title: Prévalence et génotypage multi-locus de Giardia duodenalis chez les lapins de la province du Shaanxi, nord-ouest de la Chine. Abstract: Giardia duodenalis est un parasite de grande importance vétérinaire et en santé publique dans le monde entier. La présence et les assemblages zoonotiques de G. duodenalis ont déjà été rapportés chez le lapin. Dans cette étude, pour comprendre le statut infectieux de G. duodenalis chez les lapins de la province du Shaanxi, un total de 537 échantillons fécaux ont été prélevés sur deux races de lapins dans quatre groupes d'âge (<30 jours, 31­90 jours, 91­200 jours et >200 jours) de quatre origines géographiques (Fengxiang, Yangling, Tongchuan, Shanyang). La présence de G. duodenalis dans ces échantillons a été évaluée à l'aide de tests moléculaires basés sur la bêta-giardine (bg). Les loci de la glutamate déshydrogénase (gdh) et de la triosephosphate isomérase (tpi) ont ensuite été amplifiés dans les échantillons bg-positifs pour l'analyse des génotypes multilocus (MLG). La prévalence totale de G. duodenalis chez ces lapins était de 3,54 % (19/537). L'infection à Giardia duodenalis a été trouvée chez les deux races de lapins et dans tous les élevages et groupes d'âge, mais sans différence statistiquement significative liée à ces facteurs (p > 0,05). Deux assemblages, dont B et E, ont été identifiés, le premier étant l'assemblage prédominant détecté dans les deux races, et dans tous les groupes d'âge et élevages. L'analyse des séquences a révélé des haplotypes, 2 (nommés rbg1-2), 1 (nommé rtpi1) et 2 (nommés rgdh1-2) aux loci des gènes de bg, tpi et gdh, respectivement, formant un génotype multilocus (MLG) de l'assemblage B (rbg1, rtpi1 et rgdh1). Ces résultats ont révélé l'important potentiel zoonotique et la diversité génétique de G. duodenalis chez les lapins de la province chinoise du Shaanxi.

A modified loop-mediated isothermal amplification method for detecting avian infectious laryngotracheitis virus.

This study was aimed to establish a highly specific and sensitive loop-mediated isothermal amplification (LAMP) method for diagnosing avian infectious laryngotracheitis (AILT). DNA was extracted from isolated infectious laryngotracheitis virus (ILTV) strains and control samples, followed by PCR using three sets of six specific primers. The detection efficiency of the LAMP assay was evaluated by the turbidity and calcein methods. The sensitivity of LAMP was then assessed using a concentration gradient followed by a specificity analysis. Furthermore, the detection efficiency of LAMP and PCR was compared. Finally, a clinical test was performed to evaluate the value of the LAMP assay. The optimal temperature for the LAMP reaction was 66 °C. Meanwhile, the primers selected for the LAMP assay were highly specific for the target virus. The sensitivity of the turbidity and calcein methods for LAMP was consistent. The minimum detection concentration of LAMP was 0.06 pg/µL, which was 100-fold higher than that of PCR. Furthermore, the results from clinical samples showed that the LAMP method could identify AILT from many samples. The newly designed LAMP assay was an effective method for AILT detection at an optimal temperature of 66 °C with a minimum detection concentration of 0.06 pg/µL.

Development and application of a colloidal gold test strip for the rapid detection of the infectious laryngotracheitis virus.

Infectious laryngotracheitis disease is an acute, highly contagious viral disease seriously affecting poultry industry worldwide. In this study, a rapid and simple immune colloidal gold test strip for detecting infectious laryngotracheitis virus (ILTV) was developed based on membrane chromatography with monoclonal antibodies (mAbs) against gJ protein of ILTV and systematically evaluated for the detection of ILTV from clinical samples. mAb 2D4 1D7 was conjugated with colloidal gold as the detector antibody on the test strip. Another mAb, 1D8 1G3, was used as the capture complex at the test line (T-line), and goat antimouse IgG antibody was used as the capture antibody at the control line (C-line). The colloidal gold test strip showed high specificity in the detection of ILTV, with no cross-reaction with other avian pathogens, including infectious bronchitis virus, infectious bursal disease virus, avian influenza virus, Newcastle disease virus, fowl adenoviruses, and Marek's disease virus. Besides, the detection limit of this method was as low as 60 ELD50/mL for the ILTV Wanggang strain. Furthermore, we evaluated its application in 260 clinical samples suspected of infection with ILTV. Results from the strip test were nearly identical with those from real-time PCR (coincidence rate 99.6%) and showed higher sensitivity than conventional PCR. All the results obtained in this study indicated that the colloidal gold test strip can be applied as a simple, rapid, sensitive, and specific diagnostic tool for the detection of ILTV, especially in resource-limited areas.

Emergence of two novel recombinant porcine reproductive and respiratory syndrome viruses 2 (lineage 3) in Southwestern China.

The lineage 3 of porcine reproductive and respiratory syndrome virus 2 (PRRSV-2) was first reported in mainland China in 2010 and it has spread rapidly in recent years. Here, two novel lineage 3 strains of PRRSV-2 were isolated from diseased pigs in Southwestern China during 2017-2018, and were designated as GZgy17 and SCya18. The complete genomes of the two isolates were then determined, and sequence alignment revealed that GZgy17 had the same discontinuous 30-amino acid (aa) deletion in NSP2 as JXA1, while SCya18 contained the discontinuous 131-aa deletion in NSP2 identical to that of NADC30, when compared to the strain VR-2332. Notably, GZgy17 contained an additional 19-aa deletion in NSP2, and SCya18 had a unique 3-nt deletion in its 3'UTR. Homology and phylogenetic analysis showed that GZgy17 and SCya18 shared low nucleotide homology (91.2-92.0%) with QYYZ and were classified into a new cluster of lineage 3 strains based on ORF5 genotyping. Recombination analyses revealed that GZgy17 and SCya18 both originated from a SH/CH/2016-like (lineage 3) strain and had recombined with a JXA1-like (lineage 8) and a NADC30-like (lineage 1) strain, respectively. Furthermore, we compared the virulence of the two strains in 4-week-old piglets. The results showed that GZgy17 caused mortality rates of 20% and exhibited higher pathogenicity in piglets compared to SCya18. Our findings suggest that recombination might be responsible for the variations in pathogenicity of lineage 3 strains of PRRSV-2 and highlight the importance of surveillance of this lineage in China.

Genetic characterization of a novel G9P[23] rotavirus A strain identified in southwestern China with evidence of a reassortment event between human and porcine strains.

Group A rotaviruses (RVAs) are important zoonotic pathogens that cause intestinal disease in humans and other mammals. In this study, the novel strain RVA/Pig/China/SC11/2017/G9P[23](SC11) was isolated from fecal samples from a pig farm in Sichuan province, southwestern China. The complete genome was found to be 18,347 bp in length with 11 segments. The genotype constellation of strain SC11 was G9-P[23]-I12-R1-C1-M1-A1-N1-T1-E1-H1, according to whole-genome sequencing analysis. The VP1, VP2, VP4, VP6, NSP1-NSP3, and NSP5 genes of RVA strain SC11 were found to be closely related to those of porcine and/or porcine-like human RVAs. Meanwhile, the VP7 and NSP4 genes of strain SC11 were closely related to genes of human RVAs. However, it was difficult to pinpoint the porcine or human origin of the VP3 gene of strain SC11 based on the available data. These results showed that SC11 originated from a natural reassortment event between human and pig RVA strains, and crossover points for recombination were identified at nucleotides (nt) 109-806 of NSP2. This is the first report of such a reassortant and recombinant RVA strain in the southwestern region of China.

Genetic Characterization and Pathogenicity of a Novel Recombined Porcine Reproductive and Respiratory Syndrome Virus 2 among Nadc30-Like, Jxa1-Like, and Mlv-Like Strains.

Recombination among porcine reproductive and respiratory syndrome viruses (PRRSVs), coupled with point mutations, insertions, and deletions occurring in the genome, is considered to contribute to the emergence of new variants. Here, we report the complete genome sequences of a PRRSV field strain, designated SCN17, isolated from a RespPRRS MLV-vaccinated piglet in China in 2017. Sequence alignment revealed that SCN17 had discontinuous 131-amino acid (111 + 1 + 19-aa) deletion in the NSP2-coding region identical to that of NADC30 when compared to VR-2332. Notably, the strain, SCN17, contained an additional 1-aa deletion in NSP2, a 1-aa deletion in ORF5, and a unique 3-nt deletion in the 3'-UTR. Phylogenetic analysis showed that SCN17 clustered into NADC30-like lineage based on ORF5 genotyping, whereas it belonged to an inter-lineage between the NADC30-like and VR-2332-like lineages as established based on the full-length genome. Importantly, the SCN17 was identified as a novel virus recombined between a NADC30-like (moderately pathogenic), a JXA1-like (highly pathogenic), and an attenuated vaccine strain, RespPRRS MLV (parental strain VR-2332). Furthermore, we tested its pathogenicity in piglets. SCN17 infection caused a persistent fever, moderate interstitial pneumonia, and increased the viremia and antibody levels in the inoculated piglets. Of note, all SCN17-infected piglets survived throughout the study. The new virus was showed to be a moderately virulent isolate and have lower pathogenicity than HP-PRRSV strain, SCwhn09CD. Our results provide evidence for the continuing evolution of PRRSV field strain by genetic recombination and mutation leading to outbreaks in the vaccinated pig populations in China.

Development and application of a novel Bio-Plex suspension array system for high-throughput multiplexed nucleic acid detection of seven respiratory and reproductive pathogens in swine.

The aim of this study was to develop a multiple PCR assay based on the suspension array system for the simultaneous detection of respiratory and reproductive pathogens in swine. Pseudorabies virus (PRV), Japanese encephalitis virus (JEV), classic swine fever virus (CFSV), African swine fever virus (ASFV), porcine circovirus type 2 (PCV-2), porcine reproductive and respiratory syndrome virus (PRRSV) and porcine parvovirus (PPV) are the major respiratory and reproductive viral pathogens in pig farms. Seven pairs of specific primers and probes were designed, and the multiple PCR was performed, with the PCR products hybridized to beads coupled to probes, which were then detected by Bio-Plex suspension array system. The limit of detection, specificity and repeatability of this method was determined. The assay was further tested using 137 clinical samples, and the results were compared with conventional PCR to evaluate the ability of the method to diagnose porcine viruses. The results showed that the assay had a high degree of specificity and repeatability, and the simultaneous detection limit for the seven viruses reached 103 copies/µL. Forty-nine of the clinical samples tested positive for at least one of the viruses, the principal viral infections in the clinical samples were PCV-2 and PRRSV. The suspension method represented a rapid, specific and high-throughput tool for single or mixed detection of the seven porcine viruses simultaneously, and has great significance for the development of liquid chip techniques for the diagnosis of diseases in animals.

Whole Genome Analysis of Two Novel Type 2 Porcine Reproductive and Respiratory Syndrome Viruses with Complex Genome Recombination between Lineage 8, 3, and 1 Strains Identified in Southwestern China.

Recombination among porcine reproductive and respiratory syndrome viruses (PRRSVs) is thought to contribute to the emergence of new PRRSV variants. In this study, two newly emerged PRRSV strains, designated SCcd16 and SCya17, are isolated from lung tissues of piglets in Southwestern China. Genome comparative analysis reveals that SCcd16/SCya17 exhibit 93.1%/93.2%, 86.9%/87.0%, 85.3%/85.7%, and 83.6%/82.0% nucleotide similarity to PRRSVs JXA1, VR-2332, QYYZ and NADC30, respectively. They only exhibit 44.8%/45.1% sequence identity with LV (PRRSV-1), indicating that both emergent strains belong to the PRRSV-2 genotype. Genomic sequence alignment shows that SCcd16 and SCya17 have the same discontinuous 30-amino acid (aa) deletion in Nsp2 of the highly pathogenic Chinese PRRSV strain JXA1, when compared to strain VR-2332. Notably, SCya17 shows a unique 5-nt deletion in its 3’-UTR. Phylogenetic analysis shows that both of the isolates are classified in the QYYZ-like lineage based on ORF5 genotyping, whereas they appear to constitute an inter-lineage between JXA1-like and QYYZ-like lineages based on their genomic sequences. Furthermore, recombination analyses reveal that the two newly emerged PRRSV isolates share the same novel recombination pattern. They have both likely originated from multiple recombination events between lineage 8 (JXA1-like), lineage 1 (NADC30-like), and lineage 3 (QYYZ-like) strains that have circulated in China recently. The genomic data from SCcd16 and SCya17 indicate that there is on going evolution of PRRSV field strains through genetic recombination, leading to outbreaks in the pig populations in Southwestern China.

Identification of a Novel Recombinant Type 2 Porcine Reproductive and Respiratory Syndrome Virus in China.

Since the emergence of NADC30-like porcine reproductive and respiratory syndrome virus (PRRSV) in China in 2013, PRRSVs have undergone rapid evolution. In this study, a novel variant of PRRSV strain (designated SCcd17) was successfully isolated from piglets with clinical signs in Sichuan Province in China in 2017, and the complete genomic sequence was determined. The genome of this new isolate was 15,015 nucleotides (nt) long, and comparative analysis revealed that SCcd17 exhibited 90.2%, 85.2%, 84.9%, and 84.0% nucleotide similarity to PRRSVs NADC30, JXA1, CH-1a, and VR-2332, respectively. Phylogenetic analysis indicated that the SCcd17 strain was classified into the NADC30-like sub-genotype, in which all the strains contained the unique discontinuous 131-amino acid deletion in nonstructural protein 2 (nsp2) when compared to VR-2332-like viruses. Notably, extensive amino acid substitutions were observed in nsp2 and a unique single amino acid deletion at position 33 of the GP5 is being described for the first time. Strikingly, recombination analysis revealed that SCcd17 was the result of recombination between the NADC30-like, JXA1-like, and VR-2332-like strains at five recombination breakpoints: nsp1α (nt 641), nsp3 (nt 5141), nsp10 (nt 9521), open reading frame 3 (ORF3) (nt 12,581), and ORF4 (nt 13,021). The genomic data of SCcd17 will be helpful for understanding the role of genomic recombination in the evolution of PRRSV.

Complete Genome Sequence of a Recombinant NADC30-Like Strain, SCnj16, of Porcine Reproductive and Respiratory Syndrome Virus in Southwestern China.

The NADC30-like strains of porcine reproductive and respiratory syndrome virus (PRRSV) are characterized by a 131-amino-acid deletion in nonstructural protein 2 (NSP2). Here, we report the complete genome sequence of a recombinant NADC30-like PRRSV strain, SCnj16, that exhibits the molecular marker of the Chinese highly pathogenic PRRSV (HP-PRRSV) in NSP2.

Molecular characterization and recombination analysis of porcine reproductive and respiratory syndrome virus emerged in southwestern China during 2012-2016.

Porcine reproductive and respiratory syndrome virus (PRRSV) is an important swine pathogen causing tremendous economic losses to the swine industry. To investigate the prevalence of PRRSV of genotype 2 (North American type, NA-type) in southwestern China, the Nsp2 hypervariable region (Nsp2 HV) and ORF5 of 61 PRRS viruses collected during 2012-2016 were sequenced and analyzed. All the virus detected clustered into the JXA1-like (52/61), VR-2332-like (7/61), and NADC30-like (2/61) sub-genotypes. Five deletions in Nsp2 HV were detected in addition to the typical 30aa discontinuous deletion in HP-PRRSV, and two of these five were not reported previously. Strikingly, two PRRS virus (SCnj16 and SCcd16) isolated in 2016 contained the classic HP-PRRSV molecular marker in the Nsp2-coding region, but belonged to the NADC30-like sub-genotype on the ORF5 gene. Further recombination and phylogenetic analysis on the two complete genomic sequences revealed that they may have originated from recombination events between the NADC30 and Chinese HP-PRRSV strains. The present study suggests that the endemic PRRSVs in the region have continuously evolved and new vaccine strategies are necessary for more efficient control of the virus.

Investigation on host susceptibility of Tibetan pig to infection of porcine reproductive and respiratory syndrome virus through viral challenge study.

Previous reports showed that infection of porcine reproductive and respiratory syndrome virus (PRRSV) stimulated a variable host response and pig susceptibility to PRRSV was largely dependent on its genetic composition. In the present study, host susceptibility of Tibetan pig to PRRSV was compared with other two pig breeds, ZangMei black and Large White, by challenge of them with highly pathogenic PRRSV (HP-PRRSV). In the first challenge test, each eight piglets of the three breeds were inoculated with HP-PRRSV and clinical symptoms, viremia and animal mortality were examined up to 28 days post inoculation (DPI). In the secondary pathological study, each twelve piglets of the three breeds were challenged and three pigs of each breed were sacrificed on 4, 7, and 14 DPI for examination of gross damage and lung microscopic lesions. The results showed that no typical clinical signs such as cough, diarrhea and high fever were observed in challenged Tibetan pigs, which however all occurred in Large White accompanied with ∼40% mortality (3/8). In addition, a significant low and short viremia was detected specifically in Tibetan pigs. Based on histopathological analysis of lung sections, a mild to moderate interstitial pneumonia in Tibetan pigs and a much severe pneumonia in Large White were identified on 7-14 DPI. In summary, the study demonstrated that three genetically different pig breeds exhibited a differential host susceptibility to HP-PRRSV and Tibetan pig was much less susceptible to the virus in the three tested pig breeds.

Airborne bacterial reduction by spraying slightly acidic electrolyzed water in a laying-hen house.

Spraying slightly acidic electrolyzed water (SAEW) has been considered as a potential approach to reduce airborne bacteria in laying-hen houses. In this study, the effects of spraying SAEW on airborne bacterial reduction were investigated in a laying-hen house as compared with using diluted didecyl dimethyl ammonium bromide (DDAB). Averaged air temperature reduced by approximate 1 degrees C and average relative humidity increased by 3% at a stable ventilation rate (about 2.5 m3 hr(-1) per bird) in the laying-hen house 30 min after spraying (120 mL m(-2)). Compared with the control without spraying, the airborne bacterial concentration was reduced by about 0.70 and 0.37 log10 colony-forming units (CFU) m(-3) in the 4 hr after spraying 120 mL m(-2) SAEW (available chlorine concentration [ACC] of 156 mg L(-1)) and diluted DDAB (active compound concentration of 167 mg L(-1)), respectively. Compared with spraying diluted DDAB, spraying SAEW was determined to be more effective for reducing airborne bacterial in laying-hen houses. The effects of spraying SAEW and diluted DDAB on airborne bacterial reduction in the laying-hen house increased with the increasing available chlorine concentrations for SAEW (156, 206, 262 mg L(-1)) and increasing active compound concentrations for diluted DDAB (167, 333, 500 mg L(-1)), respectively. Spraying SAEW and diluted DDAB with two levels of spraying volumes (120 and 90 mL m(-2)) both showed significant differences on airborne bacterial reduction in the laying-hen house (P < 0.05).

The protective immune response against infectious bronchitis virus induced by multi-epitope based peptide vaccines.

Peptide vaccine was found to be an effective and powerful approach to a variety of pathogens. To explore multi-epitope based peptide vaccines against infectious bronchitis virus (IBV), the immunogenic peptides were fused to the 3' terminal of glutathione S transferase gene (GST) and expressed in Escherichia coli. ELISA and Western blot analysis showed that the purified fusion proteins had excellent immune activity with chicken anti-IBV serum. During the vaccination course, the candidate peptide vaccines induced strong humoral and cellular response, and provided up to 80.0% immune protection, while all non-immunized chickens in the negative control group manifested obvious typical symptoms and died after virus challenge. Our finding provides a new way to develop multi-epitope based peptide vaccine against IBV.