ABSTRACT
Objective@#To recover broad-neutralizing monoclonal antibodies (BnAbs) from avian influenza A (H5N1) virus infection cases and investigate their genetic and functional features.@*Methods@#We screened the Abs repertoires of expanded B cells circulating in the peripheral blood of H5N1 patients. The genetic basis, biological functions, and epitopes of the obtained BnAbs were assessed and modeled.@*Results@#Two BnAbs, 2-12D5, and 3-37G7.1, were respectively obtained from two human H5N1 cases on days 12 and 21 after disease onset. Both Abs demonstrated cross-neutralizing and Ab-dependent cellular cytotoxicity (ADCC) activity. Albeit derived from distinct Ab lineages, , V 1-69-D2-15-J 4 (2-12D5) and V 1-2-D3-9-J 5 (3-32G7.1), the BnAbs were directed toward CR6261-like epitopes in the HA stem, and HA I45 in the hydrophobic pocket was the critical residue for their binding. Signature motifs for binding with the HA stem, namely, IFY in V 1-69-encoded Abs and LXYFXW in D3-9-encoded Abs, were also observed in 2-12D5 and 3-32G7.1, respectively.@*Conclusions@#Cross-reactive B cells of different germline origins could be activated and re-circulated by avian influenza virus. The HA stem epitopes targeted by the BnAbs, and the two Ab-encoding genes usage implied the VH1-69 and D3-9 are the ideal candidates triggered by influenza virus for vaccine development.
ABSTRACT
Objective@#Interferon-induced transmembrane protein 3 (IFITM3) is an important member of the IFITM family. However, the molecular mechanisms underlying its antiviral action have not been completely elucidated. Recent studies on IFITM3, particularly those focused on innate antiviral defense mechanisms, have shown that IFITM3 affects the body's adaptive immune response. The aim of this study was to determine the contribution of IFITM3 proteins to immune control of influenza infection .@*Methods@#We performed proteomics, flow cytometry, and immunohistochemistry analysis and used bioinformatics tools to systematically compare and analyze the differences in natural killer (NK) cell numbers, their activation, and their immune function in the lungs of -/- and wild-type mice.@*Results@#-/- mice developed more severe inflammation and apoptotic responses compared to wild-type mice. Moreover, the NK cell activation was higher in the lungs of -/- mice during acute influenza infection.@*Conclusions@#Based on our results, we speculate that the NK cells are more readily activated in the absence of IFITM3, increasing mortality in -/- mice.
Subject(s)
Animals , Female , Humans , Male , Mice , Acute Disease , Disease Models, Animal , Influenza, Human , Virology , Membrane Proteins , Genetics , Metabolism , Mice, Inbred C57BL , Orthomyxoviridae Infections , Virology , Rodent Diseases , VirologyABSTRACT
<p><b>OBJECTIVE</b>To determine whether it could protect mice from challenge of lethal influenza virus which group prior infected A(H1N1) pdm09 and H9N2 virus respectively.</p><p><b>METHODS</b>150 BALB/c mice are divided into three groups. Mice are infected A(H1N1) pdm09 virus (pCA07) and poultry H9N2 virus (GZ333) respectively. Infected mice are challenged with 10 times of lethal dose virus (PR8) then compare the viral load, antibody and survival of the two group mice before and after challenged.</p><p><b>RESULTS</b>Both experimental group mice survived after challenge of lethal influenza virus and lung viral load are lower than that of the first infection. Antibodies derived from the infective virus and challenge virus.</p><p><b>CONCLUSION</b>Prior infected A(H1N1) pdm09 and H9N2 virus could protect mice from challenge of lethal influenza virus.</p>
Subject(s)
Animals , Female , Humans , Mice , Antibodies, Viral , Allergy and Immunology , Influenza A Virus, H1N1 Subtype , Physiology , Influenza A Virus, H9N2 Subtype , Physiology , Influenza, Human , Allergy and Immunology , Virology , Lung , Allergy and Immunology , Virology , Mice, Inbred BALB C , Viral LoadABSTRACT
To establish the mouse-lethal model for pandemic H1N1 influenza virus, provide an animal model for studying the pathogenicity and host adaptation of 2009 pandemic H1N1 influenza virus, and find out the key amino acid mutations which may affect viral virulence and replication. A pandemic H1N1 influenza virus strain, A/Sichuan/SWL1/2009 (H1N1, SC/1) was passaged in mouse lung by 15 cycles with intranasal infection. The passaged viruses were all propagated in MDCK cells and sequenced. Based on the sequencing results, four mice in each group were inoculated with 6 selected viruses and their weight and survival rate were monitored during the following 14 days after infection. Additionally, SC/1-MA P14 and P15 viruses were sequenced after purification by Plague Assay. Viral virulence was increased after serial passages and the mortality of 100% was detected after 7 passages. Several amino acid residue mutations of passaged viruses which may contribute to the enhanced virulence were observed. The increased virulence of passaged viruses and mammalian host adaptation maybe associated with amino acid mutations in viral functional proteins. Finally, we established a mouse-lethal model.
Subject(s)
Animals , Dogs , Female , Humans , Mice , Amino Acid Substitution , Base Sequence , Cell Line , China , Epidemiology , Disease Models, Animal , Influenza A Virus, H1N1 Subtype , Genetics , Virulence , Physiology , Influenza, Human , Epidemiology , Virology , Mice, Inbred BALB C , Pandemics , Survival Analysis , Viral Plaque Assay , Virulence , Virus ReplicationABSTRACT
M2 protein of type A influenza virus is a good candidate for universal influenza vaccine, exotoxin A of Pseudomonas aeruginosa may facilitate the immunogenicity of M2 protein. We constructed and expressed a prokaryotic expression plasmid containing a chimeric gene of M2 extracellular coding region and a partial PEA gene, and observed the immunoprotection in BALB/c mice vaccinated with the fusion protein. The fusion protein (ntPE-M2e) was generated by inserting the coding sequence of the M2e in place of Ib loop in PEA. This fusion protein was used to immunize BALB/c mice by subcutaneously injection with incomplete Freund's adjuvant and boost at weeks 3 and 7. The immunized mice were challenged with influenza virus strain A/PR/34/8. The fusion protein (ntPE-M2e) immunization protected mice against lethal viral challenge. ELISA and ELISPOT results demonstrated that the fusion protein could induce a strong systemic immune response against synthetic M2e peptide, and virus replication in the lungs of mice was inhibited in comparison with the control. This study provides foundation for developing broad-spectrum vaccines against type A influenza viruses.
Subject(s)
Animals , Female , Mice , ADP Ribose Transferases , Genetics , Bacterial Toxins , Genetics , Enzyme-Linked Immunosorbent Assay , Escherichia coli , Genetics , Exotoxins , Genetics , Gene Expression , Immunization , Influenza A virus , Allergy and Immunology , Physiology , Lung , Allergy and Immunology , Virology , Mice, Inbred BALB C , Recombinant Fusion Proteins , Genetics , Allergy and Immunology , Viral Matrix Proteins , Genetics , Allergy and Immunology , Virulence Factors , GeneticsABSTRACT
<p><b>OBJECTIVE</b>To provide a technology platform for vaccine development as well as the research on transmission and pathogenesis, the reverse genetic system for H9N2 avian influenza virus was established.</p><p><b>METHODS</b>Eight full-length cDNAs of avian influenza virus A/Guangzhou/333/99 (H9N2) were amplified by RT-PCR and separately cloned into the transcription/expression vector, pCI-polI. The 8 plasmids DNA was cotransfected into 293T cell, the cell supernatant was collected and inoculated into embryonated eggs, the rescued virus from the allantoic fluid was identified by hemagglutinination assay.</p><p><b>RESULTS</b>The avian influenza H9N2 virus was successfully rescued by 8 plasmids co-transfection in 293T cells. The hemagglutinination titer of the rescued virus is up to 2(9)/50 microl and its growth curve remained relatively as to the wild-type virus.</p><p><b>CONCLUSION</b>The reverse genetic for avian influenza H9N2 subtype virus has been established successfully.</p>
Subject(s)
Animals , Chick Embryo , Female , Humans , Infant , Cell Line , Genetic Engineering , Methods , Genetic Vectors , Genetics , Influenza A Virus, H9N2 Subtype , Genetics , Physiology , Influenza, Human , Virology , Plasmids , GeneticsABSTRACT
<p><b>OBJECTIVE</b>To evaluate the efficacy of the interferon alpha-2b nasal spray in prevention of rubella and measles virus infections.</p><p><b>METHODS</b>The properly selected volunteer groups have been divided into interferon alpha-2b experimental and control group. The experimental group received interferon alpha-2b treatment by nasal spray for 2 days before the immunization, then both groups were challenged with rubella and measles attenuated live vaccine respectively through nasal spray. The sera from pre-immunization and 21 and 28 days after immunization were collected to test the IgG antibody titers. The influence on the viral antibody titer reflects the viral preventive effect by interferon alpha-2b.</p><p><b>RESULTS</b>The antibody titer difference of measles virus between experimental and control group was 1.26 (21 day) and 2.96 (28 day), there were statistically difference between them; the difference of rubella virus was 0.95 (21 day) and 0.37 (28 day), but there were no statistically differences found.</p><p><b>CONCLUSION</b>The preliminary results showed that the interferon alpha-2b can be used as prevention method for measles and rubella viral infections.</p>