A novel live attenuated vaccine candidate protects chickens against subtype B avian metapneumovirus

Avian metapneumovirus(aMPV) is a highly contagious pathogen that causes acute upper respiratory tract diseases in chickens and turkeys, resulting in serious economic losses. Subtype B aMPV has recently become the dominant epidemic strain in China. We developed an attenuated aMPV subtype B strain by serial passaging in Vero cells and evaluated its safety and efficacy as a vaccine candidate. The safety test showed that after the 30th passage, the LN16-A strain was fully attenuated, as clinical signs of infection and histological lesions were absent after inoculation.The LN16-A strain did not revert to a virulent strain after five serial passages in chickens. The genomic sequence of LN16-A differed from that of the parent wild-type LN16(wtLN16) strain and had nine amino acid mutations. In chickens, a single immunization with LN16-A induced robust humoral and cellular immune responses, including the abundant production of neutralizing antibodies, CD4^(+) T lymphocytes, and the Th1(IFN-γ) and Th2(IL-4 and IL-6)cytokines. We also confirmed that LN16-A provided 100% protection against subtype B aMPV and significantly reduced viral shedding and turbinate inflammation. Our findings suggest that the LN16-A strain is a promising live attenuated vaccine candidate that can prevent infection with subtype B aMPV.

Bone mesenchymal stem cell-derived exosomes involved co-delivery and synergism effect with icariin via mussel-inspired multifunctional hydrogel for cartilage protection

Mesenchymal stem cells(MSC)are particularly effective in promoting cartilage regeneration due to their immunomodulatory,anti-inflammatory and regenerative repair functions of tissues and organs.Meanwhile,the intra-articular delivery and synergy with other therapeutic drugs have been the key issues driving their further application.We report a mussel-inspired multifunctional hydrogel system,which could achieve co-delivery and synergism effect of MSC-derived exosomes(Exos)with icariin(ICA).The ICA and Exos co-delivered articular cavity injection system are expected to retain in the joint cavity and promote cartilage regeneration,due to the thermosensitive,self-healing and adhesion properties of the mussel-inspired multifunctional hydrogel.The experimental results proved that Exos enhanced the cellular uptake of ICA by more than 2-fold evenly,and the synergism of Exos and ICA efficiently improve the cell proliferation and migration.After synergic treatment,the content of matrix metalloproteinase 13 in the supernatant and intracellular decreased by 47%and 59%,respectively.In vivo study,ICA-loaded Exos exhibited prolonged retention behavior bymultifunctional hydrogel delivery,thus displayed an increased cartilage protection.In the model of osteoarthritis,co-delivery hydrogel system relieved the cartilage recession,ensuring appropriate cartilage thickness.

Applications and developments of gene therapy drug delivery systems for genetic diseases

Genetic diseases seriously threaten human health and have always been one of the refractory conditions facing humanity.Currently,gene therapy drugs such as siRNA,shRNA,antisense oligonucleotide,CRISPR/Cas9 system,plasmid DNA and miRNA have shown great potential in biomedical applications.To avoid the degradation of gene therapy drugs in the body and effectively deliver them to target tissues,cells and organelles,the development of excellent drug delivery vehicles is of utmost importance.Viral vectors are the most widely used delivery vehicles for gene therapy in vivo and in vitro due to their high transfection efficiency and stable transgene expression.With the development of nanotechnology,novel nanocarriers are gradually replacing viral vectors,emerging superior performance.This review mainly illuminates the current widely used gene therapy drugs,summarizes the viral vectors and non-viral vectors that deliver gene therapy drugs,and sums up the application of gene therapy to treat genetic diseases.Additionally,the challenges and opportunities of the field are discussed from the perspective of developing an effective nano-delivery system.

Micromotor-derived composites for biomedicine delivery and other related purposes

Biocompatible designed micromotor has attracted more and more concerns in the field of biomedicine due to their self-propulsion and delivery abilities.Such micromotors,mostly consisting of alkali earth metals,hydrogels,or other motile biomaterials,can effectively transform chemical energy into mechanical or kinetic energy to achieve the expected delivery of cargos to the sites of action.Except for conveying power,the modifiable surface and inner cavity of micromotors guarantee that their potential as versatile delivery systems for therapeutic agents.Here,this review generalizes the propelling mechanisms,composites,and shapes of micromotors.Besides,the application of micromotor-derived composites for biomedicine delivery and other versatile purposes are also discussed.

Synchronous conjugation of i-motif DNA and therapeutic siRNA on the vertexes of tetrahedral DNA nanocages for efficient gene silence

The functionality of DNA biomacromolecules has been widely excavated,as therapeutic drugs,carriers,and functionalized modification derivatives.In this study,we developed a series of DNA tetrahedron nanocages(Td),via synchronous conjugating different numbers of i-(X)and therapeutic siRNA on four vertexes of tetrahedral DNA nanocage(aX-Td@bsiRNA,a+b=4).This i-motif-conjugated Td exhibited good endosomal escape behaviours in A549 tumor cells,and the escape efficiency was affected by the number of i-motif.Furthermore,the downregulating mRNA and protein expression level of epidermal growth factor receptor(EGFR)caused by this siRNA embedded Td were verified in A549 cells.The tumor growth inhibition efficiency of the 2X-Td@2siRNA treated group in tumorbearing mice was significantly higher than that of non-i-motif-conjugated Td@2siRNA(3.14-fold)and free siRNA(3.63-fold).These results demonstrate a general strategy for endowing DNA nanostructures with endosomal escape behaviours to achieve effective in vivo gene delivery and therapy.

A single mutation in the PBC loop of VP2 is involved in the in vitro replication of infectious bursal disease virus

To test whether amino acid mutations in the PBC and PHI loops of VP2 are involved in the replication and virulence of infectious bursal disease virus(IBDV), a pair of viruses, namely the moderately virulent IBDV(rG x-F9VP2) and the attenuated strain(rGt), were used. Residue mutations A222P(P_(BC)) and S330R(PHI), selected by sequence comparison, were introduced individually into r Gx-F9VP2 by using a reverse genetics system. In addition, the reverse mutation of either P222 A or R330 S was introduced into r Gt. The four modified viruses were then rescued and evaluated in vitro(CEF cells) and in vivo(SPF chickens). Results showed that A222 P elevated the replication efficiency of rG x-F9VP2 while P222 A reduced that of rG t in CEF cells. A mutation at residue 330 did not alter IBDV replication. In addition, animal experiments showed that a single mutation at either residue 222 or 330 did not significantly influence the virulence of IBDV. In conclusion, residue 222 in PBC of VP2 is involved in the replication efficiency of IBDV in vitro but does not affect its virulence in vivo, further facilitating our understanding of the gene-function of IBDV.

Cryo-EM structures of infectious bursal disease viruses with different virulences provide insights into their assembly and invasion

Infectious bursal disease virus(IBDV)causes a highly contagious immunosuppressive disease in chickens,resulting in significant economic losses.The very virulent IBDV strain(vvIBDV)causes high mortality and cannot adapt to cell culture.In contrast,attenuated strains of IBDV are nonpathogenic to chickens and can replicate in cell culture.Although the crystal structure of T=1 subviral particles(SVP)has been reported,the structures of intact IBDV virions with different virulences remain elusive.Here,we determined the cryo-electron microscopy(cryo-EM)structures of the vvIBDV Gx strain and its attenuated IBDV strain Gt at resolutions of 3.3 Å and 3.2 Å,respectively.Compared with the structure of T=1 SVP,IBDV contains several conserved structural elements unique to the T=13 virion.Notably,the Nterminus of VP2,which is disordered in the SVP,interacts with the S_(F) strand of VP2 from its neighboring trimer,completing theβ-sheet of the S domain.This interaction helps to form a contact network by tethering the adjacent VP2 trimers and contributes to the assembly and stability of the IBDV virion.Structural comparison of the Gx and Gt strains indicates that H253 and T284 in the VP2 P domain of Gt,in contrast to Gx,form a hydrogen bond with a positively charged surface.This suggests that the combined mutations Q253 H/A284 T and the associated structural electrostatic features of the attenuated Gt strain may contribute to adaptation to cell culture.Furthermore,a negatively charged groove in VP2,containing an integrin binding IDA motif that is critical for virus attachment,was speculated to play a functional role in the entry of IBDV.

Pathogenic Characterization and Full Length Genome Sequence of a Reassortant Infectious Bursal Disease Virus Newly Isolated in Pakistan

Dear Editor,Infectious bursal disease (IBD) is one of the most important diseases of the poultry. The IBD virus (IBDV), a nonenveloped virus belonging to the Birnaviridae family with a genome consisting of two segments of double-stranded RNA (segments A and B), targets B lymphocytes of bursa of Fabricious leading to immunosuppression. In Pakistan,poultry farming is the second biggest industry and IBD is the second biggest disease threating the poultry sector.However.

N-terminal domain of the RNA polymerase of very virulent infectious bursal disease virus contributes to viral replication and virulence

Dear Editor,Infectious bursal disease virus （IBDV） causes an economically significant disease of chickens worldwide （Berg,2000）. The molecular basis for the virulence of very virulent IBDV （vvIBDV） is not fully understood. Previous studies have shown that genome segment A, especically VP2 protein, plays the most important role in the tropism and pathogenicity of serotype 1 IBDV （Brandt et al., 2001）. VP2 is,however, unlikely to be the only factor for the virulence of vvIBDV （Boot et al., 2000）.