Previous studies have indicated that two monoclonal antibodies (mAbs; A1-10 and H1-84) of the hemagglutinin (HA) antigen on the H1N1 influenza virus cross-react with human brain tissue. It has been proposed that there are heterophilic epitopes between the HA protein and human brain tissue (Guo et al. in Immunobiology 220:941-946, 2015). However, characterisation of the two mAbs recognising the heterophilic epitope on HA has not yet been performed. In the present study, the common antigens of influenza virus HA were confirmed using indirect enzyme-linked immunosorbent assays and analysed with DNAMAN software. The epitopes were localized to nine peptides in the influenza virus HA sequence and the distribution of the peptides in the three-dimensional structure of HA was determined using PyMOL software. Key amino acids and variable sequences of the antibodies were identified using abYsis software. The results demonstrated that there were a number of common antigens among the five influenza viruses studied that were recognised by the mAbs. One of the peptides, P2 (LVLWGIHHP 191-199), bound both of the mAbs and was located in the head region of HA. The key amino acids of this epitope and the variable regions in the heavy and light chain sequences of the mAbs that recognised the epitope are described. A heterophilic epitope on H1N1 influenza virus HA was also introduced. The existence of this epitope provides a novel perspective for the occurrence of nervous system diseases that could be caused by influenza virus infection, which might aid in influenza prevention and control.
Epidemiological studies have documented that the incidence of human type 1 diabetes was significantly increased after H1N1 epidemic. However, a direct link between human type 1 diabetes and virus infection remains elusive. We generated 84 clones of murine monoclonal antibodies against the H1N1, and carried out immunohistochemistry in normal human tissue microarray. The results showed that two clones specifically cross‐reacted with human α‐cells of pancreatic islets. Reverse transcription polymerase chain reaction and deoxyribonucleic acid sequencing showed that the amino acid sequences of light and heavy chains of these clones were different. Importantly, the expression profiles of two monoclonal antibodies were individual different. For the first time, we provide direct evidence that monoclonal antibodies against H1N1 can cross‐react with human pancreas α‐cells, another source of β‐cells, suggesting α‐cells might be a novel target to be investigated in diabetes research.
Background As an excellent xenotransplant, the pig trachea can be decellularized and cryopreserved to reduce its immunogenicity. However, few reports are found on the changes of its mechanical properties after cryopreservation and decellularization. Objective To evaluate the structure and biomechanical properties in pig tracheal scaffolds resulting from decellularized and cryopreserved. Material and methods Twenty-five pig tracheal segments were separated into five groups: untreated (group A), only decellularized (group B), only cryopreserved (group C), decellularized after cryopreserved (group D) and cryopreserved after decellularized (group E). Tracheal segments were subjected to uniaxial tension or compression using a universal testing machine to determine structural biomechanical changes. Results It showed that there was no statistically significant difference in the tensile strength of the trachea in each group. The compressive strength of group B, C and D were same as the group A ( P > 0.05), while the group E was lower than that of the group A ( P < 0.05). Conclusions and significance: The histological examination of the decellularization after cryopreservation shows that the removal of epithelial cells and submucosal cells is more thorough, and the biomechanical structure of the trachea is better preserved. This proved to be a new method to prepare xenotransplantation of trachea graft.
Following influenza A vaccination, certain individuals exhibit adverse reactions in the nervous system, which causes a problem with the safety of the influenza A vaccine. However, to the best of our knowledge, the underlying mechanism of this is unknown. The present study revealed that a monoclonal antibody (H1-84mAb) against the H1N1 influenza virus hemagglutinin (HA) protein cross-reacted with an antigen from brain tissue. Total brain tissue protein was immunoprecipitated with this cross-reactive antibody, and mass spectrometry revealed that the bound antigens were heterogeneous nuclear ribonucleoprotein (hnRNP) A1 and hnRNPA2/B1. Subsequently, the two proteins were expressed in bacteria and it was demonstrated that H1-84mAb bound to hnRNPA1 and hnRNPA2/B1. These two proteins were expressed in three segments and the cross-reactivity of H1-84mAb with the glycine (Gly)-rich domains of hnRNPA1 (195aa-320aa) and hnRNPA2/B1 (202aa-349aa) was determined using ELISA blocking experiments. It was concluded that the Gly-rich domains of these two proteins are heterophilic antigens that cross-react with influenza virus HA. The association between the heterophilic antigen Gly-rich domains and the safety of influenza A vaccines remains to be investigated.
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