Ping Wei

Molecular Characterization of Major Structural Protein Genes of Avian Coronavirus Infectious Bronchitis Virus Isolates in Southern China

To gain comprehensive genetic information of circulating avian coronavirus infectious bronchitis virus (IBV) isolates in China, analysis of the phylogenetic tree, entropy of the amino acid sequences, and the positive selection as well as computational recombinations of S1, M and N genes of 23 IBV isolates was conducted in the present study. The phylogenetic trees based on the S1, M and N genes exhibited considerably different topology and the CK/CH/LSC/99I-type isolates were the predominant IBVs based on the phylogenetic analysis of S1 gene. Results of entropy of amino acid sequences revealed that the S1 gene had the largest variation; the M gene had less variation than the N gene. Positive selections were detected in not only S1 but also M and N gene proteins. In addition, five S1 gene recombinants between vaccine strain 4/91 and CK/CH/LSC/99I-type field isolate were confirmed. In conclusion, multiple IBV genotypes co-circulated; genetic diversity and positive selections existed in S1, M and N genes; 4/91 vaccine recombinants emerged in China. Our results show that field IBVs in China are continuing to evolve and vaccine strains may have an important role in the appearance of new IBV strains via recombination. In addition, the present study indicates that IBV evolution is driven by both generations of genetic diversity and selection.

Molecular epidemiological investigation of Marek’s disease virus from Guangxi, China

The predominant field strains of Marek’s disease virus in Guangxi were clearly different from the vaccine strain CVI988/Rispens based on sequencing of the envelope glycoprotein I (gI), glycoprotein E (gE) and oncogenic meq genes. These differences may be partly responsible for the most recent outbreaks in Guangxi.

Complete Genome Sequences of Two Chinese Virulent Avian Coronavirus Infectious Bronchitis Virus Variants

ABSTRACT Avian coronavirus infectious bronchitis virus (IBV) is variable, which causes many serotypes. Here we reported the complete genome sequences of two virulent IBV variants from China, GX-YL5 and GX-YL9, belonging to different serotypes. Differences between GX-YL5 and GX-YL9 were found mainly in stem-loop structure I in the predicted RNA secondary structure of open reading frame (ORF) 1b and the S protein gene fusion region, which will help us understand the molecular evolutionary mechanism of IBV and the disconcordance between the genotypes and serotypes of coronavirus.

Complete Genome Sequence of an Infectious Bronchitis Virus Chimera between Cocirculating Heterotypic Strains

ABSTRACT To date, multiple serotypes and genotypes of infectious bronchitis virus (IBV) have been isolated and identified. In order to provide more information on the viral evolution of IBVs, a new virulent strain named GX-NN09032, isolated from Guangxi, China, in 2009, was sequenced, and phylogenetic and recombination analyses were conducted. Furthermore, potential recombination events associated with GX-NN09032 were found in four IBV strains, including GX-YL5, DY07, CK/CH/SD09/005, TC07-2. The present study suggested that GX-NN09032 might contribute to the emergence of modern IBV variants through recombination.

Molecular epidemiology studies on partial sequences of both genome segments reveal that reassortant infectious bursal disease viruses were dominantly prevalent in southern China during 2000-2012

A molecular epidemiology study of infectious bursal disease viruses (IBDVs) isolated from seven provinces in southern China during the years 2000-2012 was performed based on partial sequences of genome segments A and B, namely the hypervariable region of the A-VP2 gene (A-vVP2) and the b fragment of VP1 gene (B-VP1b) from a total of 91 field isolates. Sequence analysis based on vVP2 revealed that 72 out of 91 isolates had the same characteristic amino acid (aa) sequences as vvIBDV. The mutation of D212N in A-vVP2 has become prevalent in the recent isolates. The origin of the field isolates with vvIBDV characteristic amino acid residues was complex, evidenced by the findings that more than one subgroup of strains prevailed in each province. When B-VP1b was analyzed, there were three lineages among the field isolates, and none of the isolates had a relationship to vvIBDV-related segment B. Phylogenetic analysis of both segments revealed that only a few isolates (13/91) had the same genetic relatives in consensus trees based on segments A and B, whereas the majority of the isolates (85.71%, 78/91) were identified to be naturally reassorted strains. Based on the origin of each segment, at least six types of reassortant IBDVs prevailed in southern China, three of which were shown to be dominant: segment A from vvIBDV and B from attenuated IBDV, segment A of vvIBDV and B from 002-73-like IBDV, and segment A of vvIBDV and B from HLJ0504 or a similar strain. Our findings suggest that both genomic segments of field IBDVs has been evolving, and continuous monitoring of the evolution of field IBDV genome is therefore urgently needed in the control of IBDV.

Responses of the Toll-like receptor and melanoma differentiation-associated protein 5 signaling pathways to avian infectious bronchitis virus infection in chicks

Avian infectious bronchitis virus (IBV) is a Gammacoronavirus in the family Coronaviridae and causes highly contagious respiratory disease in chickens. Innate immunity plays significant roles in host defense against IBV. Here, we explored the interaction between IBV and the host innate immune system. Severe histopathological lesions were observed in the tracheal mucosa at 3-5 days post inoculation (dpi) and in the kidney at 8 dpi, with heavy viral loads at 1-11 and 1-28 dpi, respectively. The expression of mRNAs encoding Toll-like receptor (TLR) 3 and TLR7 were upregulated at 3-8 dpi, and that of TIR-domain-containing adapter-inducing interferon (IFN) β (TRIF) was upregulated at 21 dpi in the trachea and kidney. Myeloid differentiation primary response protein 88 (MyD88) was upregulated in the trachea during early infection. Tumor necrosis factor receptor-associated factor (TRAF) 3 and TRAF6 were upregulated expression in both tissues. Moreover, melanoma differentiation-associated protein 5 (MDA5), laboratory of genetics and physiology 2 (LGP2), stimulator of IFN genes (STING), and mitochondrial antiviral signaling protein (MAVS), as well as TANK binding kinase 1 (TBK1), inhibitor of kappaB kinase (IKK) ε, IKKα, IKKβ, IFN regulatory factor (IRF) 7, nuclear factor of kappaB (NF-ĸB), IFN-α, IFN-β, various interleukins(ILs), and macrophage inflammatory protein-1β (MIP-1β) were significantly upregulated in the trachea and downregulated in the kidney. These results suggested that the TLR and MDA5 signaling pathways and innate immune cytokine were induced after IBV infection. Additionally, consistent responses to IBV infection were observed during early infection, with differential and complicated responses in the kidney.

Role of naturally occurring genome segment reassortment in the pathogenicity of IBDV field isolates in Three-Yellow chickens.

ABSTRACT Reassortment among genome segments of infectious bursal disease virus (IBDV) field isolates was reported frequently worldwide, however the pathogenicity of the reassortant field IBDV is poorly understood. In this paper, a pathogenicity study on four representative IBDV field strains isolated from Southern China between 2005 and 2011 was conducted. Twenty-eight-day-old Three-Yellow chickens were divided into four groups and were inoculated intraocularly with one of the four field IBDV strains, namely NN1172, NN1005, GD10111 and JS7, respectively. The mortality and relative weight of bursa and thymus were subsequently determined in the acute phase of infection. In addition, B cells, T cells (CD4+ and CD8+) and virus were quantified in the bursa of Fabricius and thymus, respectively, by flow cytometry and real-time reverse transcription-polymerase chain reaction. The results showed that isolate NN1172, of which parts of segment A and B encoding the hypervariable (v) region of viral protein (VP2) and VP1, respectively, derived from vvIBDV strains, showed the most severe pathogenicity, and caused the most severe bursal B cell depletion as well as CD4+ and CD8+ T cell infiltration in the bursa of Fabricius. However, the virus induced the strongest decrease in CD4+ and CD8+ T cells in the thymus and exhibited the most efficient viral replication in the target organs. Isolate NN1005, whose vVP2 derived from vvIBDV and VP1 from unidentified origin, exhibited relatively lower pathogenicity compared to NN1172. The other two isolates, JS7 and GD10111, of which the vVP2 derived from vvIBDV and intermediate IBDV, and VP1 from 002–73 and attenuated IBDV, respectively, showed the lowest level of virulence. Our results suggest that various IBDV field isolates with different natural segment reassortments exhibit differential pathogenicity after infection of commercial Three-Yellow chickens.

Full-length genome sequence analysis of an avian leukosis virus subgroup J (ALV-J) as contaminant in live poultry vaccine: The commercial live vaccines might be a potential route for ALV-J transmission

One avian leukosis virus subgroup J (ALV-J) strain was isolated from 67 commercial live poultry vaccines produced by various manufacturers during 2013-2016 in China. The complete genomes of the isolate were sequenced and it was found that the genes gag and pol of the strain were relatively conservative, while the gp85 gene of the strain GX14YYA1 had the highest similarities with a field strain GX14ZS14, which was isolated from the chickens of a farm that had once used the same vaccine as the one found to be contaminated with the GX14YYA1. This is the first report of ALV-J contaminant in live poultry vaccine in China. Our finding demonstrates that vaccination of the commercial live vaccines might be a potential new route for ALV-J transmission in chickens and highlights the need for more extensive monitoring of the commercial live vaccines in China.

Protection against Virulent Infectious Bronchitis Virus Challenge Conferred by a Recombinant Baculovirus Co-Expressing S1 and N Proteins

Avian infectious bronchitis virus (IBV) is the causative agent of infectious bronchitis, which results in considerable economic losses. It is imperative to develop safe and efficient candidate vaccines to control IBV infection. In the current study, recombinant baculoviruses co-expressing the S1 and N proteins and mono-expressing S1 or N proteins of the GX-YL5 strain of IBV were constructed and prepared into subunit vaccines rHBM-S1-N, rHBM-S1 and rHBM-N. The levels of immune protection of these subunit vaccines were evaluated by inoculating specific pathogen-free (SPF) chickens at 14 days of age, giving them a booster with the same dose 14 days later and challenging them with a virulent GX-YL5 strain of IBV 14 days post-booster (dpb). The commercial vaccine strain H120 was used as a control. The IBV-specific antibody levels, as well as the percentages of CD4+ and CD8+ T lymphocytes, were detected within 28 days post-vaccination (dpv). The morbidity, mortality and re-isolation of the virus from the tracheas and kidneys of challenged birds were evaluated at five days post-challenge (dpc). The results showed that the IBV-specific antibody levels and the percentages of CD4+ and CD8+ T lymphocytes were higher in the rHBM-S1-N vaccinated birds compared to birds vaccinated with the rHBM-S1 and rHBM-N vaccines. At 5 dpc, the mortality, morbidity and virus re-isolation rate of the birds vaccinated with the rHBM-S1-N vaccine were slightly higher than those vaccinated with the H120 control vaccine but were lower than those vaccinated with the rHBM-S1 and rHBM-N vaccines. The present study demonstrated that the protection of the recombinant baculovirus co-expressing S1 and N proteins was better than that of recombinant baculoviruses mono-expressing the S1 or N protein. Thus, the recombinant baculovirus co-expressing S1 and N proteins could serve as a potential IBV vaccine and this demonstrates that the bivalent subunit vaccine including the S1 and N proteins might be a strategy for the development of an IBV subunit vaccine.

Antigenicity characterization of four representative natural reassortment IBDVs isolated from commercial three-yellow chickens from Southern China reveals different subtypes co-prevalent in the field

The antigenic relationships between the natural reassortment field strains of infectious bursal disease virus (IBDV), and between the field strains and the vaccine strains are poorly understood. In the present study, the antigenicity of four representative natural reassortment IBDV isolates designated JS7, GD10111, NN1005 and NN1172 from southern China during the years 2005-2011 and their antigenic relationship with the most commonly used vaccine strain B87 were investigated in vivo. For this purpose, cross-challenge studies were performed on 28-day-old birds, which were 2 weeks post-vaccination by oil-emulsion vaccines (OEVs) prepared from the four field viruses and B87, respectively. The protection related values (PRV) were evaluated based on the protection rate measured by clinical signs and mortality, bursa/body weight (B/BW) ratio and the viral load in the bursal samples at 3 and 7 days post challenge. As a result, the PRV showed that the isolates NN1172 and GD10111 belonged to the same antigenic subtype, while the isolates NN1005 and JS7 belong to another subtype. The vaccine strain B87 was grouped with the isolates NN1005 and JS7 but actually belongs to another small subgroup and provided only 60-80% protection against the challenge of the four field strains. The results demonstrated that different antigenic subtypes co-existed among the field natural reassortment IBDV strains and the commonly used vaccine strain B87 was antigenically different from the prevalent IBDVs in southern China.