The Inducing Roles of the New Isolated Bursal Hexapeptide and Pentapeptide on the Immune Response of AIV Vaccine in Mice

Abstract

Background: Bursa of Fabricius is the acknowledged central humoral immune organ. The bursal-derived peptides play the important roles on the immature B cell development and antibody production. Objective: Here we explored the functions of the new isolated bursal hexapeptide and pentapeptide on the humoral, cellular immune response and antigen presentation to Avian Influenza Virus (AIV) vaccine in mice immunization. Methods: The bursa extract samples were purified following RP HPLC method, and were analyzed with MS/MS to identify the amino acid sequences. Mice were twice subcutaneously injected with AIV inactivated vaccine plus with two new isolated bursal peptides at three dosages, respectively. On two weeks after the second immunization, sera samples were collected from the immunized mice to measure AIV-specific IgG antibody levels and HI antibody titers. Also, on 7th day after the second immunization, lymphocytes were isolated from the immunized mice to detect T cell subtype and lymphocyte viabilities, and the expressions of co-stimulatory molecule on dendritic cells in the immunized mice. Results: Two new bursal hexapeptide and pentapeptide with amino acid sequences KGNRVY and MPPTH were isolated, respectively. Our investigation proved the strong regulatory roles of bursal hexapeptide on AIV-specific IgG levels and HI antibody titers, and lymphocyte viabilities, and the significant increased T cells subpopulation and expressions of MHCII molecule on dendritic cells in the immunized mice. Moreover, our findings verified the significantly enhanced AIV-specific IgG antibody and HI titers, and the strong increased T cell subpopulation and expressions of CD40 molecule on dendritic cells in the mice immunized with AIV vaccine and bursal pentapeptide. Conclusion: We isolated and identified two new hexapeptide and pentapeptide from bursa, and proved that these two bursal peptides effectively induced the AIV-specific antibody, T cell and antigen presentation immune responses, which provided an experimental basis for the further clinical application of the bursal derived active peptide on the vaccine improvement.

SARS-CoV-2-Induced Immunosuppression: A Molecular Mimicry Syndrome

“…Pentapeptide sharing between SARS-CoV-2 proteins and human immunodeficiency–related proteins was analyzed using pentapeptide as a sequence probe because a peptide grouping formed by five aa residues defines a minimal immune determinant underlying the specific interaction of an antigen with B-cell receptor (BCR) and T-cell receptor (TCR). 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 The results are displayed in Table 1 .…”

“…To prove/disprove the cross-reactivity paradigm, the present study comparatively analyzed the entire SARS-CoV-2 proteome and human proteins involved in immunodeficiencies searching for common amino acid (aa) sequences. Using the pentapeptide as the basic measurement unit of antigenicity and immunogenicity, 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 sequence analyses revealed peptide commonalities that are susceptible of generating cross-reactions, thus feasibly explaining the immunosuppression associated with SARS-CoV-2 passive/active infection and its increase following repeated anti-SARS-CoV-2 vaccinations.…”

Hydrophobicity and the Physico-Chemical Basis of Immunotolerance

“…This datum was defined with mathematical precision since the 1930s, when Landsteiner and van der Scheer [16] demonstrated by inhibition reactions that pentapeptides serve as specific immune determinants in the generation of specific antibodies. Then, analysis of the binding energy in antigen-antibody complexes, site-directed mutagenesis, and epitope mapping experiments definitively validated the pentapeptide as a minimal measurement unit of immune recognition [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. In parallel, also the maximum size of polysaccharide epitopes was found to be close to that of penta-or hexasaccharides, corresponding to the same maximum specific surface area as that for peptides [17,21,22].…”

From Anti-EBV Immune Responses to the EBV Diseasome via Cross-reactivity

“…Immunologically, Tables 1 and 2 document that the experimentally validated immunoreactive EBV epitopes mostly consist of pentapeptides that also occur in human proteins, in this way indicating a highest cross-reactivity potential, given the fact that a pentapeptide is a minimal immune determinant that contains the immunological information in terms of both immunogenicity and antigenicity. 43 44 45 46 47 48 …”

“…That is, the thesis is explored according to which the anti-EBV immune responses that should be a "protective defense" from EBV infection actually cross-react with human proteins, in this way setting up an anti-human protein assault with catastrophic pathologic sequelae in the body. Specifically, the present study used the pentapeptide as an antigenic and immunogenic unit, [43][44][45][46][47][48] and analyzed 3,197 experimentally validated immunoreactive EBV-derived epitopes for pentapeptide matches with the human proteome. Data are reported on a vast peptide sharing between EBV epitopes and proteins involved in tumorigenesis, autoimmune disorders, diabetes, and death, among others.…”