A New Segmented Virus Associated with Human Febrile Illness in China.

BACKGROUND: In 2017, surveillance for tickborne diseases in China led to the identification of a patient who presented to a hospital in Inner Mongolia with a febrile illness that had an unknown cause. The clinical manifestation of the illness was similar to that of tickborne encephalitis virus (TBEV) infection, but neither TBEV RNA nor antibodies against the virus were detected. METHODS: We obtained a blood specimen from the index patient and attempted to isolate and identify a causative pathogen, using genome sequence analysis and electron microscopy. We also initiated a heightened surveillance program in the same hospital to screen for other patients who presented with fever, headache, and a history of tick bites. We used reverse-transcriptase-polymerase-chain-reaction (RT-PCR) and cell-culture assays to detect the pathogen and immunofluorescence and neutralization assays to determine the levels of virus-specific antibodies in serum specimens from the patients. RESULTS: We found that the index patient was infected with a previously unknown segmented RNA virus, which we designated Alongshan virus (ALSV) and which belongs to the jingmenvirus group of the family Flaviviridae. ALSV infection was confirmed by RT-PCR assay in 86 patients from Inner Mongolia and Heilongjiang who presented with fever, headache, and a history of tick bites. Serologic assays showed that seroconversion had occurred in all 19 patients for whom specimens were available from the acute phase and the convalescent phase of the illness. CONCLUSIONS: A newly discovered segmented virus was found to be associated with a febrile illness in northeastern China. (Funded by the National Key Research and Development Program of China and the National Natural Science Foundation of China.).

Genetic characterization of H9N2 avian influenza virus in plateau pikas in the Qinghai Lake region of China.

Qinghai Lake is a major migratory-bird breeding site that has experienced several highly pathogenic avian influenza virus (AIV) epizootics. Plateau pikas (Ochotona curzoniae) have previously been implicated in the ecology of avian influenza virus in this region. We first isolated an H9N2 AIV (A/Pika/Menyuan/01/2008) from plateau pikas between November 2008 and October 2009. Sequence analysis showed that the A/Pika/Menyuan/01/2008 AIV was closely related to the H9N2 AIV strain (A/Turkey/Wisconsin/ 1/1966). Our findings suggested that plateau pikas may contribute to AIV epidemiology in the Qinghai Lake region.

Rabies virus matrix protein induces apoptosis by targeting mitochondria.

Apoptosis, as an innate antiviral defense, not only functions to limit viral replication by eliminating infected cells, but also contribute to viral dissemination, particularly at the late stages of infection. A highly neurotropic CVS strain of rabies virus induces apoptosis both in vitro and in vivo. However, the detailed mechanism of CVS-mediated neuronal apoptosis is not entirely clear. Here, we show that CVS induces apoptosis through mitochondrial pathway by dissipating mitochondrial membrane potential, release of cytochrome c and AIF. CVS blocks Bax activation at the early stages of infection; while M protein partially targets mitochondria and induces mitochondrial apoptosis at the late stages of infection. The α-helix structure spanning 67-79 amino acids of M protein is essential for mitochondrial targeting and induction of apoptosis. These results suggest that CVS functions on mitochondria to regulate apoptosis at different stages of infection, so as to for viral replication and dissemination.

Rabies virus inactivates cofilin to facilitate viral budding and release.

Cytoplasmic actin and actin-associated proteins have been identified in RABV particles. Although actin is involved in RABV entry into cells, the specific role of actin in RABV budding and release remains unknown. Our study found that RABV M protein-mediated virion budding depends on intact actin filaments. Confocal microscopy demonstrated a block to virions budding, with a number of M protein-mediated budding vesicles detained in the cell cytoplasm. Furthermore, RABV infection resulted in inactivation of cofilin and upregulation of phosphorylated cofilin. Knockdown of cofilin reduced RABV release. These results for the first time indicate that RABV infection resulted in upregulation of phosphorylated cofilin to facililtate actin polymerization for virus budding.

Evidence of recombinant strains of porcine epidemic diarrhea virus, United States, 2013.

To investigate the evolutionary process by which porcine epidemic diarrhea virus (PEDV) in the United States hypothetically descended from strains in China, we analyzed PEDV-positive samples collected in China during January 2012-July 2013. Recombination in 2 strain sublineages was likely associated with identification of PEDV in the United States in 2013.

The Inactivated gE/TK Gene-Deleted Vaccine Against Pseudorabies Virus Type II Confers Effective Protection in Mice and Pigs.

The highly virulent and antigenic variant of Pseudorabies virus (PRV) that emerged from classical Bartha-K61-vaccinated pig herds has caused substantial economic losses to the swine industry in China since 2011. A safe and more effective vaccine is most desirable. In this study, a gE/TK gene-deficient PRV, namely, HD/c, was constructed based on a PRV type II DX strain isolated from a commercial vaccine-immunized farm and the HD/c-based inactivated vaccine was formulated and evaluated for its safety, immunogenicity, and protective efficacy in mice and piglets. The resulting PRV HD/c strain has a similar growth curve to the parental DX strain. After vaccination, the inactivated HD/c vaccine did not cause any visible gross pathological or histopathological changes in the tissues of mice and piglets and provided rapid and potent protection against the challenge of the classical and variant PRVs at day 21 post-vaccination in mice. A single immunization of 108.5TCID50 inactivated PRV HD/c strain-elicited robust immunity with high titer of neutralizing antibody and provided complete protection from the lethal challenge of PRV DX strain in piglets. These results indicated that the inactivated PRV HD/c vaccine with the deletion of gE/TK genes was a safe and effective PRV vaccine candidate for the control of PRV.

Genomic characterization of a proventriculitis-associated infectious bronchitis coronavirus.

Transmissible proventriculitis associated with infectious bronchitis virus (IBV) was at first seen in eastern China in mid-1995, and is now endemic in China. Herein, the complete genome sequence of a proventiculitis-associated infectious bronchitis coronavirus (ZJ971) was sequenced and analyzed. Compared with the genome of the vaccine strain H120, ZJ971 had 54 nucleotide substitutions and a deletion in the 3'-UTR. The substitutions were in the regions of nsp2-nsp5, nsp7, nsp12, nsp13, nsp15, S and N genes, and the untranslating region. The results indicated that ZJ971 could be a variant of IBV strain H120.

Fine mapping of antigenic epitopes on capsid proteins of porcine circovirus, and antigenic phenotype of porcine circovirus type 2.

Type 2 porcine circovirus (PCV2) is associated with post-weaning multisystemic wasting syndrome in pigs. In this study, three monoclonal antibodies (mAbs) against the capsid protein (Cap) of PCV2, eight mAbs to Cap of type 1 porcine circovirus (PCV1) and five mAbs specific for Cap of both PCV1 and PCV2, were generated and used to finely map the antigenic sites of PCV1 and PCV2, and to identify the antigenic phenotype of PCV2 with different length of genome. Five linear B-cell epitopes, including the residues 231-233 and 195-202 specific for PCV2, residues 92-103 specific for PCV1, and residues 156-162 and 175-192 shared between PCV1 and PCV2, were finely defined with synthetic peptides, and the critical residue in epitope 231-233 and 156-162 was located at residues 233 ((233)Proline) and 156 ((156)Tyrosine), respectively. The conformational epitopes recognized by mAbs with neutralizing activity against both PCV1 and PCV2 were detected in transfected PK-15 and the residues 231-233 also participated in the formation of conformational epitopes. Analysis of antigenic diversity on these epitopes exhibited three antigenic phenotypes of PCV2, (1766)PCV2, (1767)PCV2 and (1768)PCV2 using mAbs. The results from this study first demonstrated the different antigenic phenotype between PCV2 isolates.

Novel circovirus species identified in farmed pigs designated as Porcine circovirus 4, Hunan province, China.

In pigs, three circovirus species within the genus Circovirus have been identified so far, including the non-pathogenic Porcine circovirus 1 (PCV1), the pathogenic Porcine circovirus 2 (PCV2) and the recently identified Porcine circovirus 3 (PCV3). In April 2019, a new circovirus with a distinct relationship to other circoviruses was identified in several pigs with severe clinical disease in Hunan province, China. The size of the viral genome, tentatively designated as porcine circovirus type 4 (PCV4), is 1,770 nucleotides (nt). PCV4 shows the highest genomic identity to mink circovirus (66.9%) and has identities of 43.2%-51.5% to the other PCV genomes. Two major genes, a replicase (Rep) gene spanning 891 nt and a capsid (Cap) gene spanning 687 nt, were predicted. Furthermore, a TaqMan® real-time polymerase chain reaction (PCR) targeting the replicase gene was developed to investigate the prevalence of PCV4 in 187 clinical samples from Hunan province, China. The results revealed an overall PCV4 prevalence of 12.8%, with the highest positive rates in nasal swabs (28.5%, 6/21) followed by serum samples (13.4%, 11/82). The clinical significance and pathogenesis of this virus needs further investigation.

[Expressions of CXCL13, CD10 and bcl-6 in angioimmunoblastic T-cell lymphoma and peripheral T-cell lymphoma, not otherwise specified].

OBJECTIVE: To study the value of immunomarkers CXCL13, CD10, bcl-6 in pathologic diagnosis of angioimmunoblastic T-cell lymphoma (AITL). METHODS: One hundred and fifteen cases of AITL, 30 cases of peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) and 30 cases of reactive lymph nodes with paracortical hyperplasia (RH) encountered during the period from January, 1990 to January, 2008 were retrieved from the archival files of the Department of Pathology, West China Hospital of Sichuan University, China. The morphologic features were reviewed and compared. Immunohistochemical study was performed by SP method for CXCL13, CD10, bcl-6, CD21, CD3epsilon, CD3, CD45RO, CD20 and Ki-67. TCR-gamma gene rearrangement study was also carried out. RESULTS: Regressed follicles were evident in 7.8% (9/115) of AITL cases, 6.7% (2/30) of PTCL, NOS cases and 83.3% (25/30) of RH cases, respectively. A marked increase of number of arborizing venules was shown in 98.3% (113/115) of AITL cases, 63.3% (19/30) of PTCL, NOS cases and 76.7% (23/30) of RH cases, respectively. In lymph nodes with paracortical hyperplasia, the expression of CXCL13, CD10 and bcl-6 were restricted to the germinal centers. In AITL, 96.5% (111/115) of cases showed CXCL13 expression, in contrast to 26.7% (8/30) of PTCL, NOS. Expression of CD10 and bcl-6 were found in the neoplastic cells in 50.4% (58/115) and 78.3% (90/115) of AITL, and 3.3% (1/30) and 3.3% (1/30) of PTCL, NOS, respectively. Irregular meshworks of CD21-positive follicular dendritic cells were found in all the AITL cases. Clonal TCR-gamma rearrangement was detected in 83% (83/100) of the AITL cases. CONCLUSIONS: AITL is a type of lymphoma originated from the follicular helper T cells. Detailed morphologic assessment and use of immunohistochemical markers are essential for accurate diagnosis.

Pathogenicity of an FAdV-4 isolate to chickens and its genomic analysis.

Fowl adenovirus serotype 4 (FAdV-4) strain SD1511 was isolated from chickens with severe inclusion body hepatitis and hydropericardium syndrome in Shandong Province, China. The isolate was cultured in primary chicken embryo kidney cells. A study of pathogenicity indicated that SD1511 readily infected 7-35-d-old chickens by intramuscular injection and intranasal and oral routes, causing 50%-100% mortality. The 35-d-old chickens suffered more severe infection than 7- and 21-d-old chickens with mortality highest in the intramuscular injection group. The serum from surviving chickens showed potent viral neutralizing capability. The complete genome of SD1511 was sequenced and analyzed. The strain was found to belong to the FAdV-4 cluster with more than 99% identity with the virulent FAdV-4 strains isolated in China in recent years except for some distinct variations, including deletions of open reading frame 27 (ORF27), ORF48, and part of ORF19. Our findings suggest that SD1511 might be used as a prototype strain for the study of pathogenesis and vaccine development.

Development and validation of a recombinant capsid protein-based ELISA for detection of antibody to porcine circovirus type 2.

Porcine circovirus type 2 (PCV2) has been recently associated with a number of disease syndromes, especially postweaning multisystemic wasting disease (PMWS). Herein, an alternative indirect enzyme-linked immunosorbent assay (ELISA) for detection of PCV2 antibody was developed using nuclear localization signal-truncated capsid protein of PCV2 produced in Escherichia coli (CAP ELISA). This assay was validated by comparison with an indirect immunofluorescence assay (IIF) and a PCV2-based ELISA. The diagnostic sensitivity (DSN), specificity (DSP) and accuracy of the CAP ELISA were 95.3%, 93.9% and 95.1%, compared with IIF on 1080 field serum samples, and 93.3%, 84.2% and 91.1%, compared with the PCV2-based ELISA on 79 field sera, respectively. Cross-reactivity assay showed that this assay was PCV2-specific. Repeatability tests revealed that the coefficients of variation of positive sera within and between runs were less than 15%. This ELISA is simpler to produce and perform, time-saving and suitable for large scale surveys of PCV2 infection at low cost and the evaluation of the efficiency of various vaccines against PCV2.

Rabies Virus Infection Induces Microtubule Depolymerization to Facilitate Viral RNA Synthesis by Upregulating HDAC6.

Rabies virus (RABV) is the cause of rabies, and is associated with severe neurological symptoms, high mortality rate, and a serious threat to human health. Although cellular tubulin has recently been identified to be incorporated into RABV particles, the effects of RABV infection on the microtubule cytoskeleton remain poorly understood. In this study, we show that RABV infection induces microtubule depolymerization as observed by confocal microscopy, which is closely associated with the formation of the filamentous network of the RABV M protein. Depolymerization of microtubules significantly increases viral RNA synthesis, while the polymerization of microtubules notably inhibits viral RNA synthesis and prevents the viral M protein from inducing the formation of the filamentous network. Furthermore, the histone deacetylase 6 (HDAC6) expression level progressively increases during RABV infection, and the inhibition of HDAC6 deacetylase activity significantly decreases viral RNA synthesis. In addition, the expression of viral M protein alone was found to significantly upregulate HDAC6 expression, leading to a substantial reduction in its substrate, acetylated α-tubulin, eventually resulting in microtubule depolymerization. These results demonstrate that HDAC6 plays a positive role in viral transcription and replication by inducing microtubule depolymerization during RABV infection.

Mitochondrial dynamics controls anti-tumour innate immunity by regulating CHIP-IRF1 axis stability.

Macrophages, dendritic cells and other innate immune cells are involved in inflammation and host defense against infection. Metabolic shifts in mitochondrial dynamics may be involved in Toll-like receptor agonist-mediated inflammatory responses and immune cell polarization. However, whether the mitochondrial morphology in myeloid immune cells affects anti-tumor immunity is unclear. Here we show that FAM73b, a mitochondrial outer membrane protein, has a pivotal function in Toll-like receptor-regulated mitochondrial morphology switching from fusion to fission. Switching to mitochondrial fission via ablation of Fam73b (also known as Miga2) promotes IL-12 production. In tumor-associated macrophages, this switch results in T-cell activation and enhances anti-tumor immunity. We also show that the mitochondrial morphology affects Parkin expression and its recruitment to mitochondria. Parkin controls the stability of the downstream CHIP-IRF1 axis through proteolysis. Our findings identify mechanisms associated with mitochondrial dynamics that control anti-tumor immune responses and that are potential targets for cancer immunotherapy.

Characterization of chicken interleukin 2 receptor alpha chain, a homolog to mammalian CD25.

To identify chicken IL-2R alpha chain (chCD25), the cDNA of chCD25 was cloned and mapped onto chicken chromosome 1. The polyclonal and monoclonal antibodies raised from the recombinant chCD25 specifically bound to the cell surface of splenic mononuclear cells (SMC) and inhibited chicken IL-2-dependent proliferation of T cells. Flow cytometry analysis revealed that chCD25 molecules could be expressed on the surface of monocytes/macrophages, thrombocytes, CD4+ and CD8+ cells as well as tissue cells. Importantly, the CD4+CD25+ and CD8+CD25+ cells were upregulated dramatically in chickens infected with H9N2 avian influenza virus. These results confirm that the cloned cDNA is the nucleotide sequence of chicken IL-2R, and suggest that chicken CD4+CD25+ and CD8+CD25+ cells may play an important role in immune responses induced by H9N2 virus, and the monoclonal antibodies to chCD25 may be useful for investigating biological functions of chicken regulatory T cells.

The celiac ganglia: anatomic study using MRI in cadavers.

OBJECTIVE: Our objective was to facilitate the in vivo identification of the celiac ganglia on MRI by using MRI to identify the celiac ganglia in cadavers. CONCLUSION: MRI can show the celiac ganglia accurately in cadavers when the ganglia are large and labeled with gadolinium. The findings in cadavers can be a reference for identifying the celiac ganglia in vivo.

Cloning, in vitro expression and bioactivity of duck interleukin-2.

In this report, the cDNA sequences of Shaoxing (SX) and Muscovy (MV) duck IL-2 were cloned, then recombinant duck IL-2 (rduIL-2) was produced in prokaryotic expression system. In vitro bioactivity of rduIL-2 was determined by lymphocyte proliferation assay and in vivo bioactivity of rduIL-2 was assessed by vaccine immunization. Monoclonal antibodies (mAbs) and polyclonal antibodies (pAbs) specific for rduIL-2 were generated and characterized by ELISA, Western blot and neutralizing assays. The cDNA contains an open reading frame (ORF) of 420-base pairs encoding a protein of 140 amino acids (aa) with a putative signal peptide of 21aa. The His-duIL-2 fusion protein was recognized in Western blot by mAb against chicken IL-2 (chIL-2), but not by mAbs against human IL-2 and mouse IL-2. Recombinant duIL-2 induces in vitro proliferation of Con A-stimulated duck splenocytes in MTT assay and strengthens duck immune responses induced by vaccinating the inactivated oil emulsion vaccine against avian influenza virus. Polyclonal antibodies and mAb 2B3 against rduIL-2 were shown to have effective neutralizing ability by inhibiting the biological activities of both recombinant duIL-2 and endogenous duIL-2. Despite the fact that duck and chicken IL-2s only share identity of 55.0-56.7% in amino acid sequence, duck and chicken IL-2 molecules displayed similar cross-priming activity in in vitro lymphocyte proliferation assays. The results, at the first time, indicated that rduIL-2 has the potential to be used as an immunoadjuvant for enhancing vaccine efficacy and an immunotherapeutic, and the mAbs against rduIL-2 further facilitate basic immunobiological studies of the role of IL-2 in avian immune system.

Identification of neutralizing epitopes on the VP2 protein of infectious bursal disease virus by phage-displayed heptapeptide library screening and synthetic peptide mapping.

Infectious bursal disease virus (IBDV) is the causative agent of infectious bursal disease, which is one of the most important and widespread infectious diseases in commercial chickens. Conformational epitopes have been reported in the highly variable region of the VP2 protein of IBDV. In the present study, a random heptapeptide library was screened by using monoclonal antibodies (mAbs), YNW17 and YNW29, directed to the VP2 of IBDV and two peptide motifs, D-X-P-R and A-R-G, were identified. The motifs are present on the N and C terminal sequences of the highly variable region of VP2. Synthetic overlapping peptides covering the motifs on VP2 were analyzed by Dot- ELISA with the mAbs and two epitopes 197CDSSDRPRVYTIT209 and 329ARGSLAVTI337 identified. The above epitopes were also recognized by chicken anti-IBDV sera and shown to inhibit the binding of their mAbs to recombinant VP2. Both mAbs and sera from mice immunized with the conjugated epitope-peptides were able to neutralize serotype I IBDV. These results indicated that the epitopes are two neutralizing linear B-cell epitopes and would be useful for the development of peptide-based IBD vaccines.

In vitro expression, monoclonal antibody and bioactivity for capsid protein of porcine circovirus type II without nuclear localization signal.

We expressed firstly the Capsid protein gene defecting the nuclear localization signal (NLS) of Porcine circovirus type II (PCV2) in Escherichia coli as a fusion protein with glutathione S-transferase (rGST-dCap protein). The purified rGST-dCap protein and the recombinant NLS-defected Cap protein of PCV2 (rdCap protein) from the purified rGST-dCap protein reacted specifically with swine antiserum to PCV2. Furthermore, the obtained monoclonal antibodies (mAbs) to rdCap protein were shown to bind to PCV2 particles replicated in PK15 cell and capsid protein (Cap protein) of PCV2 expressed in PK15 cells, respectively. mAbs to rdCap protein also revealed the neutralizing ability to PCV2 particles. These results demonstrated that rGST-dCap protein expressed in E. coli was folded correctly or at least partly, and mAbs to rdCap protein possessed the binding epitopes of PCV2 particles whereas mAbs 4C4 and 3F6 to rdCap protein remained the neutralization epitope of PCV2 particle, showing a possibility of neutralizing mAb to rdCap protein as an immnuotherapeutic agent and a potential of rGST-dCap protein as a vaccine antigen or serodiagnostic reagent.

[Antigenic analysis of the recombinant capsid protein of porcine circovirus type 2].

The nuclear localization signal (NLS)-defected capsid protein gene (dCap) of porcine circovirus type 2 (PCV2) was expressed firstly in Escherichia coli as a fusion protein with glutathione S-transferase (rGST-dCap protein). The purified rGST-dCap protein and NLS-defected Cap protein of PCV2 (rdCap protein) from the purified rGST-dCap protein reacted specifically with swine antiserum to PCV2. Furthermore, the obtained monoclonal antibodies (mAbs) to rdCap protein were shown to bind to PCV2 particles replicated in PK15 cell. MAbs to rdCap protein also revealed the neutralizing ability to PCV2 particles. These results demonstrate that rGST-dCap protein expressed in E. coli is folded correctly or at least partly, and all mAbs to rdCap protein possess the binding epitopes of PCV2 particle whereas mAbs 4C4,3F6 and 2G7 to rdCap protein keep the neutralization epitopes of PCV2 particle, showing a potential of rGST-dCap protein as a vaccine antigen or serodiagnostic reagent.