RESUMO
Porcine deltacoronavirus (PDCoV) was first detected in Hong Kong and has recently spread to many countries around the world. PDCoV causes acute diarrhea and vomiting in pigs, resulting in significant economic losses in the global pork industry. In this study, a Chinese PDCoV strain, designated CHN-HG-2017, was isolated from feces of a suckling piglet with severe watery diarrhea on a farm located in central China. Subsequently, the virus was identified by an indirect immunofluorescence assay and electron microscopy. A nucleotide sequence alignment showed that the whole genome of CHN-HG-2017 is 97.6%-99.1% identical to other PDCoV strains. Analysis of potential recombination sites showed that CHN-HG-2017 is a possible recombinant originating from the strains CH/SXD1/2015 and Vietnam/HaNoi6/2015. Furthermore, the pathogenicity of this recombinant PDCoV strain was investigated in 5-day-old piglets by oral inoculation. The challenged piglets developed typical symptoms, such as vomiting, anorexia, diarrhea and lethargy, from 1 to 7 days post-inoculation (DPI). Viral shedding was detected in rectal swabs until 14 DPI in the challenged piglets. Interestingly, high titers of virus-neutralizing antibodies in sera were detected at 21 DPI. Tissues of small intestines from CHN-HG-2017-infected piglets at 4 DPI displayed significant macroscopic and microscopic lesions with clear viral antigen expression. Our analysis of the full genome sequence of a recombinant PDCoV and its virulence in suckling piglets might provide new insights into the pathogenesis of PDCoV and facilitate further investigation of this newly emerged pathogen.
Assuntos
Infecções por Coronavirus/veterinária , Coronavirus/isolamento & purificação , Coronavirus/patogenicidade , Doenças dos Suínos/virologia , Animais , China , Coronavirus/classificação , Coronavirus/genética , Infecções por Coronavirus/virologia , Diarreia/veterinária , Diarreia/virologia , Fezes/virologia , Genoma Viral , Genômica , Filogenia , Suínos , Vietnã , VirulênciaRESUMO
Enhancing cross-protections against diverse influenza viruses is desired for influenza vaccinations. Neuraminidase (NA)-specific antibody responses have been found to independently correlate with a broader influenza protection spectrum. Here, we report a sequential immunization regimen that includes priming with NA protein followed by boosting with peptide nanoclusters, with which targeted enhancement of antibody responses in BALB/c mice to certain cross-protective B-cell epitopes of NA was achieved. The nanoclusters were fabricated via desolvation with absolute ethanol and were only composed of composite peptides. Unlike KLH conjugates, peptide nanoclusters would not induce influenza-unrelated immunity. We found that the incorporation of a hemagglutinin peptide of H2-d class II restriction into the composite peptides could be beneficial in enhancing the NA peptide-specific antibody response. Of note, boosters with N2 peptide nanoclusters induced stronger serum cross-reactivities to heterologous N2 and even heterosubtypic N7 and N9 than triple immunizations with the prototype recombinant tetrameric (rt) N2. The mouse challenge experiments with HK68 H3N2 also demonstrated the strong effectiveness of the peptide nanocluster boosters in conferring heterologous protection.
Assuntos
Influenza Humana , Neuraminidase , Animais , Camundongos , Humanos , Influenza Humana/prevenção & controle , Vírus da Influenza A Subtipo H3N2 , Peptídeos , Imunização Secundária , Anticorpos , Camundongos Endogâmicos BALB CRESUMO
Influenza virus infection poses a continual menace to public health. Here, we developed soluble trimeric HA ectodomain vaccines by establishing interprotomer disulfide bonds in the stem region, which effectively preserve the native antigenicity of stem epitopes. The stable trimeric H1 ectodomain proteins exhibited higher thermal stabilities in comparison with unmodified HAs and showed strong binding activities towards a panel of anti-stem cross-reactive antibodies that recognize either interprotomer or intraprotomer epitopes. Negative stain transmission electron microscopy (TEM) analysis revealed the stable trimer architecture of the interprotomer disulfide-stapled WA11#5, NC99#2, and FLD#1 proteins as well as the irregular aggregation of unmodified HA molecules. Immunizations of mice with those trimeric HA ectodomain vaccines formulated with incomplete Freund's adjuvant elicited significantly more potent cross-neutralizing antibody responses and offered broader immuno-protection against lethal infections with heterologous influenza strains compared to unmodified HA proteins. Additionally, the findings of our study indicate that elevated levels of HA stem-specific antibody responses correlate with strengthened cross-protections. Our design strategy has proven effective in trimerizing HA ectodomains derived from both influenza A and B viruses, thereby providing a valuable reference for designing future influenza HA immunogens.
Assuntos
Anticorpos Neutralizantes , Anticorpos Antivirais , Dissulfetos , Glicoproteínas de Hemaglutininação de Vírus da Influenza , Vacinas contra Influenza , Camundongos Endogâmicos BALB C , Infecções por Orthomyxoviridae , Animais , Vacinas contra Influenza/imunologia , Vacinas contra Influenza/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/química , Anticorpos Antivirais/imunologia , Camundongos , Dissulfetos/química , Infecções por Orthomyxoviridae/prevenção & controle , Infecções por Orthomyxoviridae/imunologia , Infecções por Orthomyxoviridae/virologia , Anticorpos Neutralizantes/imunologia , Feminino , Proteção Cruzada/imunologia , Reações Cruzadas , Humanos , Influenza Humana/prevenção & controle , Influenza Humana/imunologia , Influenza Humana/virologia , Epitopos/imunologia , Epitopos/genética , Epitopos/química , Multimerização Proteica , Vírus da Influenza B/imunologia , Vírus da Influenza B/genética , Vírus da Influenza B/químicaRESUMO
Neuraminidase is suggested as an important component for developing a universal influenza vaccine. Targeted induction of neuraminidase-specific broadly protective antibodies by vaccinations is challenging. To overcome this, we rationally select the highly conserved peptides from the consensus amino acid sequence of the globular head domains of neuraminidase. Inspired by the B cell receptor evolution process, a reliable sequential immunization regimen is designed to result in immuno-focusing by steering bulk immune responses to a selected region where broadly protective B lymphocyte epitopes reside. After priming neuraminidase protein-specific antibody responses in C57BL/6 or BALB/c inbred mice strains by immunization or pre-infection, boost immunizations with certain neuraminidase-derived peptide-keyhole limpet hemocyanin conjugates significantly strengthened serum neuraminidase inhibition activities and cross-protections. Overall, this study provides proof of concept for a peptide-based sequential immunization strategy for achieving targeted induction of cross-protective antibody response, which provides references for designing universal vaccines against other highly variable pathogens.
Assuntos
Vírus da Influenza A Subtipo H1N1 , Virus da Influenza A Subtipo H5N1 , Vacinas contra Influenza , Influenza Humana , Infecções por Orthomyxoviridae , Animais , Camundongos , Humanos , Infecções por Orthomyxoviridae/prevenção & controle , Neuraminidase , Anticorpos Antivirais , Camundongos Endogâmicos C57BL , Vacinação , Peptídeos , Camundongos Endogâmicos BALB C , Glicoproteínas de Hemaglutininação de Vírus da InfluenzaRESUMO
Influenza virus hemagglutinin (HA) stem is currently regarded as an extremely promising immunogen for designing universal influenza vaccines. The appropriate antigen-presenting vaccine vector would be conducive to increasing the immunogenicity of the HA stem antigen. In this study, we generated chimeric virus-like particles (cVLPs) co-displaying the truncated C-terminal of DnaK from Escherichia coli and H1 stem or full-length H1 antigen using the baculovirus expression system. Transmission electronic micrography revealed the expression and presentation of H1 stem antigens on the surface of VLPs. Vaccinations of mice with the H1 stem cVLPs induced H1-specific immune responses and provided heterologous immune protection in vivo, which was more effective than vaccinations with VLPs displaying H1 stem alone in protecting mice against weight loss as well as increasing survival rates after lethal influenza viral challenge. The results indicate that the incorporation of the truncated C-terminal of DnaK as an adjuvant protein into the cVLPs significantly enhances the H1-specific immunity and immune protection. We have explicitly identified the VLP platform as an effective way of expressing HA stem antigen and revealed that chimeric VLP is an vaccine vector for developing HA stem-based universal influenza vaccines.